Efficient production of spin singlets in lattice-confined spinor condensates

NASA Astrophysics Data System (ADS)

Zhao, Lichao; Chen, Zihe; Tang, Tao; Liu, Yingmei

2017-04-01

We present an efficient experimental scheme for a production of spin singlets in an antiferromagnetic spinor condensate confined by a cubic optical lattice. Via two independent detection methods, we demonstrate that about 80 percent of atoms in the lattice-confined spinor condensate can form spin singlets, immediately after the atoms cross a first-order superfluid to Mott-insulator phase transition in a sufficiently low microwave dressing field. We also discuss a good agreement between our data and the mean field theory, and two applications of spin singlets in quantum information science. We thank the National Science Foundation and the Oklahoma Center for the Advancement of Science and Technology for financial support.

Topological solitons in 8-spinor mie electrodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rybakov, Yu. P., E-mail: soliton4@mail.ru

2013-10-15

We investigate the effective 8-spinor field model suggested earlier as the generalization of nonlinear Mie electrodynamics. We first study in pure spinorial model the existence of topological solitons endowed with the nontrivial Hopf invariant Q{sub H}, which can be interpreted as the lepton number. Electromagnetic field being included as the perturbation, we estimate the energy and the spin of the localized charged configuration.

Antiferromagnetic spinor condensates in a bichromatic superlattice

NASA Astrophysics Data System (ADS)

Tang, Tao; Zhao, Lichao; Chen, Zihe; Liu, Yingmei

2017-04-01

A spinor Bose-Einstein condensate in an optical supelattice has been considered as a good quantum simulator for understanding mesoscopic magnetism. We report an experimental study on an antiferromagnetic spinor condensate in a bichromatic superlattice constructed by a cubic red-detuned optical lattice and a one-dimensional blue-detuned optical lattice. Our data demonstrate a few advantages of this bichromatic superlattice over a monochromatic lattice. One distinct advantage is that the bichromatic superlattice enables realizing the first-order superfluid to Mott-insulator phase transitions within a much wider range of magnetic fields. In addition, we discuss an apparent discrepancy between our data and the mean-field theory. We thank the National Science Foundation and the Oklahoma Center for the Advancement of Science and Technology for financial support.

Coherent magnon optics in a ferromagnetic spinor Bose-Einstein condensate.

PubMed

Marti, G Edward; MacRae, Andrew; Olf, Ryan; Lourette, Sean; Fang, Fang; Stamper-Kurn, Dan M

2014-10-10

We measure the dispersion relation, gap, and magnetic moment of a magnon in the ferromagnetic F = 1 spinor Bose-Einstein condensate of (87)Rb. From the dispersion relation we measure an average effective mass 1.033(2)(stat)(10)(sys) times the atomic mass, as determined by interfering standing and running coherent magnon waves within the dense and trapped condensed gas. The measured mass is higher than theoretical predictions of mean-field and beyond-mean-field Beliaev theory for a bulk spinor Bose gas with s-wave contact interactions. We observe a magnon energy gap of h × 2.5(1)(stat)(2)(sys) Hz, which is consistent with the predicted effect of magnetic dipole-dipole interactions. These dipolar interactions may also account for the high magnon mass. The effective magnetic moment of -1.04(2)(stat)(8)(sys) times the atomic magnetic moment is consistent with mean-field theory.

Spinorial characterizations of surfaces into three-dimensional homogeneous manifolds

NASA Astrophysics Data System (ADS)

Roth, Julien

2010-06-01

We give spinorial characterizations of isometrically immersed surfaces into three-dimensional homogeneous manifolds with four-dimensional isometry group in terms of the existence of a particular spinor field. This generalizes works by Friedrich for R3 and Morel for S3 and H3. The main argument is the interpretation of the energy-momentum tensor of such a spinor field as the second fundamental form up to a tensor depending on the structure of the ambient space.

Dirac operator on spinors and diffeomorphisms

NASA Astrophysics Data System (ADS)

Dąbrowski, Ludwik; Dossena, Giacomo

2013-01-01

The issue of general covariance of spinors and related objects is reconsidered. Given an oriented manifold M, to each spin structure σ and Riemannian metric g there is associated a space Sσ, g of spinor fields on M and a Hilbert space {H}_{σ, g}= L^2(S_{σ, g}, vol_{g}(M)) of L2-spinors of Sσ, g. The group Diff+(M) of orientation-preserving diffeomorphisms of M acts both on g (by pullback) and on [σ] (by a suitably defined pullback f*σ). Any f ∈ Diff+(M) lifts in exactly two ways to a unitary operator U from {H}_{σ, g} to {H}_{f^*σ ,f^*g}. The canonically defined Dirac operator is shown to be equivariant with respect to the action of U, so in particular its spectrum is invariant under the diffeomorphisms.

Spinor helicity methods in high-energy factorization: Efficient momentum-space calculations in the Color Glass Condensate formalism

NASA Astrophysics Data System (ADS)

Ayala, Alejandro; Hentschinski, Martin; Jalilian-Marian, Jamal; Tejeda-Yeomans, Maria Elena

2017-07-01

We use the spinor helicity formalism to calculate the cross section for production of three partons of a given polarization in Deep Inelastic Scattering (DIS) off proton and nucleus targets at small Bjorken x. The target proton or nucleus is treated as a classical color field (shock wave) from which the produced partons scatter multiple times. We reported our result for the final expression for the production cross section and studied the azimuthal angular correlations of the produced partons in [1]. Here we provide the full details of the calculation of the production cross section using the spinor helicity methods.

Universality of nonthermal behavior in spinor Bose condensates

NASA Astrophysics Data System (ADS)

Patil, Yogesh Sharad; Cheung, Hil F. H.; Shaffer, Airlia; Chen, Huiyao Y.; Vengalattore, Mukund

2016-05-01

Spinor Bose condensates exhibit a rich phase diagram with varied magnetic ordering and topological defects because of the close competition between their spin and charge dependent interactions. Quenching such a spinor condensate into a ferromagnetic state realizes robust non-equilibrium and prethermalized states whose macroscopic behavior differs from thermodynamic predictions. In previous work, we have identified the microscopic origin of prethermalization in Rubidium spinor gases as being the disparate energy scales of the phonon and magnon excitations in this gas. This identification of the microscopic origin enables us to broaden the scope of our studies to address fundamental questions regarding the equilibration of isolated quantum systems. We will discuss our recent results that suggest the universality of this coarsening behavior and evidence that this system can be mapped on to a non-thermal fixed point studied in high energy field theories. This work is supported by the ARO MURI on non-equilibrium dynamics.

Conformal superalgebras via tractor calculus

NASA Astrophysics Data System (ADS)

Lischewski, Andree

2015-01-01

We use the manifestly conformally invariant description of a Lorentzian conformal structure in terms of a parabolic Cartan geometry in order to introduce a superalgebra structure on the space of twistor spinors and normal conformal vector fields formulated in purely algebraic terms on parallel sections in tractor bundles. Via a fixed metric in the conformal class, one reproduces a conformal superalgebra structure that has been considered in the literature before. The tractor approach, however, makes clear that the failure of this object to be a Lie superalgebra in certain cases is due to purely algebraic identities on the spinor module and to special properties of the conformal holonomy representation. Moreover, it naturally generalizes to higher signatures. This yields new formulas for constructing new twistor spinors and higher order normal conformal Killing forms out of existing ones, generalizing the well-known spinorial Lie derivative. Moreover, we derive restrictions on the possible dimension of the space of twistor spinors in any metric signature.

Quantization of spinor fields. III. Fermions on coherent (Bose) domains

NASA Astrophysics Data System (ADS)

Garbaczewski, Piotr

1983-02-01

A formulation of the c-number classics-quanta correspondence rule for spinor systems requires all elements of the quantum field algebra to be expanded into power series with respect to the generators of the canonical commutation relation (CCR) algebra. On the other hand, the asymptotic completeness demand would result in the (Haag) expansions with respect to the canonical anticommutation relation (CAR) generators. We establish the conditions under which the above correspondence rule can be reconciled with the existence of Haag expansions in terms of asymptotic free Fermi fields. Then, the CAR become represented on the state space of the Bose (CCR) system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernando, Sudarshan; Günaydin, Murat

We study the minimal unitary representation (minrep) of SO(5, 2), obtained by quantization of its geometric quasiconformal action, its deformations and supersymmetric extensions. The minrep of SO(5, 2) describes a massless conformal scalar field in five dimensions and admits a unique “deformation” which describes a massless conformal spinor. Scalar and spinor minreps of SO(5, 2) are the 5d analogs of Dirac’s singletons of SO(3, 2). We then construct the minimal unitary representation of the unique 5d supercon-formal algebra F(4) with the even subalgebra SO(5, 2) ×SU(2). The minrep of F(4) describes a massless conformal supermultiplet consisting of two scalar andmore » one spinor fields. We then extend our results to the construction of higher spin AdS 6/CFT 5 (super)-algebras. The Joseph ideal of the minrep of SO(5, 2) vanishes identically as operators and hence its enveloping algebra yields the AdS 6/CFT 5 bosonic higher spin algebra directly. The enveloping algebra of the spinor minrep defines a “deformed” higher spin algebra for which a deformed Joseph ideal vanishes identically as operators. These results are then extended to the construction of the unique higher spin AdS 6/CFT 5 superalgebra as the enveloping algebra of the minimal unitary realization of F(4) obtained by the quasiconformal methods.« less

Fermionic Schwinger effect and induced current in de Sitter space

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hayashinaka, Takahiro; Department of Physics, Graduate School of Science, The University of Tokyo,Bunkyo-ku, Tokyo, 113-0033; Fujita, Tomohiro

We explore Schwinger effect of spin 1/2 charged particles with static electric field in 1+3 dimensional de Sitter spacetime. We analytically calculate the vacuum expectation value of the spinor current which is induced by the produced particles in the electric field. The renormalization is performed with the adiabatic subtraction scheme. We find that the current becomes negative, namely it flows in the direction opposite to the electric field, if the electric field is weaker than a certain threshold value depending on the fermion mass, which is also known to happen in the case of scalar charged particles in 1+3 demore » Sitter spacetime. Contrary to the scalar case, however, the IR hyperconductivity is absent in the spinor case.« less

Non-existence of rest-frame spin-eigenstate spinors in their own electrodynamics

NASA Astrophysics Data System (ADS)

Fabbri, Luca; da Rocha, Roldão

2018-05-01

We assume a physical situation where gravity with torsion is neglected for an electrodynamically self-interacting spinor that will be taken in its rest-frame and spin-eigenstate: we demonstrate that under this circumstance no solution exists for the system of field equations. Despite such a situation might look artificial nevertheless it represents the instance that is commonly taken as the basis for all computations of quantum electrodynamics.

The nontriviality of trivial general covariance: How electrons restrict 'time' coordinates, spinors (almost) fit into tensor calculus, and 7/16 of a tetrad is surplus structure

NASA Astrophysics Data System (ADS)

Brian Pitts, J.

2012-02-01

It is a commonplace in the philosophy of physics that any local physical theory can be represented using arbitrary coordinates, simply by using tensor calculus. On the other hand, the physics literature often claims that spinors as such cannot be represented in coordinates in a curved space-time. These commonplaces are inconsistent. What general covariance means for theories with fermions, such as electrons, is thus unclear. In fact both commonplaces are wrong. Though it is not widely known, Ogievetsky and Polubarinov constructed spinors in coordinates in 1965, enhancing the unity of physics and helping to spawn particle physicists' concept of nonlinear group representations. Roughly and locally, these spinors resemble the orthonormal basis or "tetrad" formalism in the symmetric gauge, but they are conceptually self-sufficient and more economical. The typical tetrad formalism is de-Ockhamized, with six extra field components and six compensating gauge symmetries to cancel them out. The Ogievetsky-Polubarinov formalism, by contrast, is (nearly) Ockhamized, with most of the fluff removed. As developed nonperturbatively by Bilyalov, it admits any coordinates at a point, but "time" must be listed first. Here "time" is defined in terms of an eigenvalue problem involving the metric components and the matrix diag(-1,1,1,1), the product of which must have no negative eigenvalues in order to yield a real symmetric square root that is a function of the metric. Thus even formal general covariance requires reconsideration; the atlas of admissible coordinate charts should be sensitive to the types and values of the fields involved. Apart from coordinate order and the usual spinorial two-valuedness, (densitized) Ogievetsky-Polubarinov spinors form, with the (conformal part of the) metric, a nonlinear geometric object, for which important results on Lie and covariant differentiation are recalled. Such spinors avoid a spurious absolute object in the Anderson-Friedman analysis of substantive general covariance. They also permit the gauge-invariant localization of the infinite-component gravitational energy in General Relativity. Density-weighted spinors exploit the conformal invariance of the massless Dirac equation to show that the volume element is absent. Thus instead of an arbitrary nonsingular matrix with 16 components, six of which are gauged away by a new local O(1,3) gauge group and one of which is irrelevant due to conformal covariance, one can, and presumably should, use density-weighted Ogievetsky-Polubarinov spinors coupled to the nine-component symmetric unimodular square root of the part of the metric that fixes null cones. Thus 7/16 of the orthonormal basis is eliminated as surplus structure. Greater unity between spinors (related to fermions, with half-integral spin) and tensors and the like (related to bosons, with integral spin) is achieved, such as regarding conservation laws. Regarding the conventionality of simultaneity, an unusually wide range of ɛ values is admissible, but some extreme values are inadmissible. Standard simultaneity uniquely makes the spinor transformation law linear and independent of the metric, because transformations among the standard Cartesian coordinate systems fall within the conformal group, for which the spinor transformation law is linear. The surprising mildness of the restrictions on coordinate order as applied to the Schwarzschild solution is exhibited.

Creating Spin-One Fermions in the Presence of Artificial Spin-Orbit Fields: Emergent Spinor Physics and Spectroscopic Properties

NASA Astrophysics Data System (ADS)

Kurkcuoglu, Doga Murat; de Melo, C. A. R. Sá

2018-05-01

We propose the creation and investigation of a system of spin-one fermions in the presence of artificial spin-orbit coupling, via the interaction of three hyperfine states of fermionic atoms to Raman laser fields. We explore the emergence of spinor physics in the Hamiltonian described by the interaction between light and atoms, and analyze spectroscopic properties such as dispersion relation, Fermi surfaces, spectral functions, spin-dependent momentum distributions and density of states. Connections to spin-one bosons and SU(3) systems is made, as well relations to the Lifshitz transition and Pomeranchuk instability are presented.

Hairy strings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sahakian, Vatche

Zero modes of the world-sheet spinors of a closed string can source higher order moments of the bulk supergravity fields. In this work, we analyze various configurations of closed strings focusing on the imprints of the quantized spinor vacuum expectation values onto the tails of bulk fields. We identify supersymmetric arrangements for which all multipole charges vanish; while for others, we find that one is left with Neveu-Schwarz-Neveu-Schwarz, and Ramond-Ramond dipole and quadrupole moments. Our analysis is exhaustive with respect to all the bosonic fields of the bulk and to all higher order moments. We comment on the relevance ofmore » these results to entropy computations of hairy black holes of a single charge or more, and to open/closed string duality.« less

Field equations from Killing spinors

NASA Astrophysics Data System (ADS)

Açık, Özgür

2018-02-01

From the Killing spinor equation and the equations satisfied by their bilinears, we deduce some well-known bosonic and fermionic field equations of mathematical physics. Aside from the trivially satisfied Dirac equation, these relativistic wave equations in curved spacetimes, respectively, are Klein-Gordon, Maxwell, Proca, Duffin-Kemmer-Petiau, Kähler, twistor, and Rarita-Schwinger equations. This result shows that, besides being special kinds of Dirac fermions, Killing fermions can be regarded as physically fundamental. For the Maxwell case, the problem of motion is analysed in a reverse manner with respect to the studies of Einstein-Groemer-Infeld-Hoffmann and Jean Marie Souriau. In the analysis of the gravitino field, a generalised 3-ψ rule is found which is termed the vanishing trace constraint.

Spinor Bose-Einstein Condensates of Positronium

NASA Astrophysics Data System (ADS)

Wang, Yi-Hsieh; Anderson, Brandon; Clark, Charles

2014-05-01

Bose-Einstein condensates (BECs) of positronium (Ps) have been of experimental and theoretical interest due to their potential application as the gain medium of a γ-ray laser. Ps BECs are intrinsically spinor due to the presence of ortho-positronium (o-Ps) and para-positronium (p-Ps), whose annihilation lifetimes differ by three orders of magnitude. In this paper, we study the spinor dynamics and annihilation processes in the p-Ps/o-Ps system using both solutions of the time-dependent Gross-Pitaevskii equations and a semiclassical rate-equation approach. The spinor interactions have an O (4) symmetry which is broken to SO (3) by an internal energy difference between o-Ps and p-Ps. For an initially unpolarized condensate, there is a threshold density of ~1019 cm-3 at which spin mixing between o-Ps and p-Ps occurs. Beyond this threshold, there are unstable spatial modes accompanied by spin mixing. To ensure a high production yield above the critical density, a careful choice of external field must be made to avoid the spin mixing instability. NSF Physics Frontiers Center, ARO Atomtronics MURI, DARPA OLE.

Soliton configurations in generalized Mie electrodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rybakov, Yu. P., E-mail: soliton4@mail.ru

2011-07-15

The generalization of the Mie electrodynamics within the scope of the effective 8-spinor field model is suggested, with the Lagrangian including Higgs-like potential and higher degrees of the invariant A{sub Micro-Sign }A{sup Micro-Sign }. Using special Brioschi 8-spinor identity, we show that the model includes the Skyrme and the Faddeev models as particular cases. We investigate the large-distance asymptotic of static solutions and estimate the electromagnetic contribution to the energy of the localized charged configuration.

Quantum gravity in three dimensions, Witten spinors and the quantisation of length

NASA Astrophysics Data System (ADS)

Wieland, Wolfgang

2018-05-01

In this paper, I investigate the quantisation of length in euclidean quantum gravity in three dimensions. The starting point is the classical hamiltonian formalism in a cylinder of finite radius. At this finite boundary, a counter term is introduced that couples the gravitational field in the interior to a two-dimensional conformal field theory for an SU (2) boundary spinor, whose norm determines the conformal factor between the fiducial boundary metric and the physical metric in the bulk. The equations of motion for this boundary spinor are derived from the boundary action and turn out to be the two-dimensional analogue of the Witten equations appearing in Witten's proof of the positive mass theorem. The paper concludes with some comments on the resulting quantum theory. It is shown, in particular, that the length of a one-dimensional cross section of the boundary turns into a number operator on the Fock space of the theory. The spectrum of this operator is discrete and matches the results from loop quantum gravity in the spin network representation.

Minimal unitary representation of 5d superconformal algebra F(4) and AdS 6/CFT 5 higher spin (super)-algebras

DOE PAGES

Fernando, Sudarshan; Günaydin, Murat

2014-11-28

We study the minimal unitary representation (minrep) of SO(5, 2), obtained by quantization of its geometric quasiconformal action, its deformations and supersymmetric extensions. The minrep of SO(5, 2) describes a massless conformal scalar field in five dimensions and admits a unique “deformation” which describes a massless conformal spinor. Scalar and spinor minreps of SO(5, 2) are the 5d analogs of Dirac’s singletons of SO(3, 2). We then construct the minimal unitary representation of the unique 5d supercon-formal algebra F(4) with the even subalgebra SO(5, 2) ×SU(2). The minrep of F(4) describes a massless conformal supermultiplet consisting of two scalar andmore » one spinor fields. We then extend our results to the construction of higher spin AdS 6/CFT 5 (super)-algebras. The Joseph ideal of the minrep of SO(5, 2) vanishes identically as operators and hence its enveloping algebra yields the AdS 6/CFT 5 bosonic higher spin algebra directly. The enveloping algebra of the spinor minrep defines a “deformed” higher spin algebra for which a deformed Joseph ideal vanishes identically as operators. These results are then extended to the construction of the unique higher spin AdS 6/CFT 5 superalgebra as the enveloping algebra of the minimal unitary realization of F(4) obtained by the quasiconformal methods.« less

Analytical Tools for Investigating and Modeling Agent-Based Systems

DTIC Science & Technology

2005-06-01

of Black Holes Cluster 10 : Juan M. Maldacena (1924), Journal of High Energy Physics Field theory models for tachyon and gauge field string dy...namics; Super-Poincare Invariant Superstring Field The- ory; Level Four Approximation to the Tachyon Potential in Superstring Field Theory; SO(32) Spinors

Goos-Hänchen-like shift in biased silicene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhu, Bang-Shan; Wang, Yu, E-mail: ywang@semi.ac.cn; Lou, Yi-Yi

2016-04-28

We have theoretically studied the Goos-Hänchen-like shift of spinor-unpolarized beams tunneling through various gate-biased silicene nanostructures. Following the stationary-phase method, lateral displacement in single-, dual-, and multiple-gated silicene systems has been systematically demonstrated. It is shown for simple single-gated silicene that lateral displacement can be generally enhanced by Fabry-Perot interference, and near the transition point turning on the evanescent mode a very large lateral shift could be observed. For the dual-gated structure, we have also shown the crucial role of localized modes like quantum well states in enhancing the beam lateral displacement, while for the multiple gate-biased systems the resultingmore » superlattice subbands are also favorable for lateral displacement enhancement. Importantly, including the degeneracy-broken mechanisms such as gate-field and magnetic modulations, a fully spinor-resolved beam can be distinguished from the rest counterparts by aligning the incident beam with a proper spinor-resolved transition point, localized state, and subband, all of which can be flexibly modulated via electric means, offering the very desirable strategies to achieve the fully spinor-polarized beam for functional electronic applications.« less

Beyond Discrete Vacuum Spacetimes

NASA Astrophysics Data System (ADS)

McDonald, Jonathan; Miller, Warner

2008-04-01

In applications to pre-geometric models of quantum gravity, one expects matter to play an important role in the geometry of the spacetime. Such models often posit that the matter fields play a crucial role in the determination of the spacetime geometry. However, it is not well understood at a fundamental level how one couples matter into the Regge geometry. In order to better understand the nature of such theories that rely on Regge Calculus, we must first gain a better understanding of the role of matter in a lattice spacetime. We investigate consistent methods of incorporating matter into spacetime, and particularly focus on the role of spinors in Regge Calculus. Since spinors are fundamental to fermionic fields, this investigation is crucial in understanding fermionic coupling to discrete spacetime. Our focus is primarily on the geometric interpretation of the fields on the lattice geometry with a goal on understanding the dynamic coupling between the fields and the geometry.

Einstein-Yang-Mills-Dirac systems from the discretized Kaluza-Klein theory

NASA Astrophysics Data System (ADS)

Wali, Kameshwar; Viet, Nguyen Ali

2017-01-01

A unified theory of the non-Abelian gauge interactions with gravity in the framework of a discretized Kaluza-Klein theory is constructed with a modified Dirac operator and wedge product. All the couplings of chiral spinors to the non-Abelian gauge fields emerge naturally as components of the coupling of the chiral spinors in the generalized gravity together with some new interactions. In particular, the currently prevailing gravity-QCD quark and gravity-electroweak-quark and lepton models are shown to follow as special cases of the general framework.

Singularity-free spinors in gravity with propagating torsion

NASA Astrophysics Data System (ADS)

Fabbri, Luca

2017-12-01

We consider the most general renormalizable theory of propagating torsion in Einstein gravity for the Dirac matter distribution and we demonstrate that in this case, torsion is a massive axial-vector field whose coupling to the spinor gives rise to conditions in terms of which gravitational singularities are not bound to form; we discuss how our results improve those that are presented in the existing literature, and that no further improvement can be achieved unless one is ready to re-evaluate some considerations on the renormalizability of the theory.

Spinor formulation of topologically massive gravity

NASA Astrophysics Data System (ADS)

Aliev, A. N.; Nutku, Y.

1995-12-01

In the framework of real 2-component spinors in three dimensional space-time we present a description of topologically massive gravity (TMG) in terms of differential forms with triad scalar coefficients. This is essentially a real version of the Newman-Penrose formalism in general relativity. A triad formulation of TMG was considered earlier by Hall, Morgan and Perjes, however, due to an unfortunate choice of signature some of the spinors underlying the Hall-Morgan-Perjes formalism are real, while others are pure imaginary. We obtain the basic geometrical identities as well as the TMG field equations including a cosmological constant for the appropriate signature. As an application of this formalism we discuss the Bianchi Type $VIII - IX$ exact solutions of TMG and point out that they are parallelizable manifolds. We also consider various re-identifications of these homogeneous spaces that result in black hole solutions of TMG.

Critical Spin Superflow in a Spinor Bose-Einstein Condensate

NASA Astrophysics Data System (ADS)

Kim, Joon Hyun; Seo, Sang Won; Shin, Y.

2017-11-01

We investigate the critical dynamics of spin superflow in an easy-plane antiferromagnetic spinor Bose-Einstein condensate. Spin-dipole oscillations are induced in a trapped condensate by applying a linear magnetic field gradient and we observe that the damping rate increases rapidly as the field gradient increases above a certain critical value. The onset of dissipation is found to be associated with the generation of dark-bright solitons due to the modulation instability of the counterflow of two spin components. Spin turbulence emerges as the solitons decay because of their snake instability. We identify another critical point for spin superflow, in which transverse magnon excitations are dynamically generated via spin-exchanging collisions, which leads to the transient formation of axial polar spin domains.

Spinors: A Mathematica package for doing spinor calculus in General Relativity

NASA Astrophysics Data System (ADS)

Gómez-Lobo, Alfonso García-Parrado; Martín-García, José M.

2012-10-01

The Spinors software is a Mathematica package which implements 2-component spinor calculus as devised by Penrose for General Relativity in dimension 3+1. The Spinors software is part of the xAct system, which is a collection of Mathematica packages to do tensor analysis by computer. In this paper we give a thorough description of Spinors and present practical examples of use. Program summary Program title: Spinors Catalogue identifier: AEMQ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEMQ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 117039 No. of bytes in distributed program, including test data, etc.: 300404 Distribution format: tar.gz Programming language: Mathematica. Computer: Any computer running Mathematica 7.0 or higher. Operating system: Any operating system compatible with Mathematica 7.0 or higher. RAM: 94Mb in Mathematica 8.0. Classification: 1.5. External routines: Mathematica packages xCore, xPerm and xTensor which are part of the xAct system. These can be obtained at http://www.xact.es. Nature of problem: Manipulation and simplification of spinor expressions in General Relativity. Solution method: Adaptation of the tensor functionality of the xAct system for the specific situation of spinor calculus in four dimensional Lorentzian geometry. Restrictions: The software only works on 4-dimensional Lorentzian space-times with metric of signature (1, -1, -1, -1). There is no direct support for Dirac spinors. Unusual features: Easy rules to transform tensor expressions into spinor ones and back. Seamless integration of abstract index manipulation of spinor expressions with component computations. Running time: Under one second to handle and canonicalize standard spinorial expressions with a few dozen indices. (These expressions arise naturally in the transformation of a spinor expression into a tensor one or vice versa.)

Spinor matter fields in SL(2,C) gauge theories of gravity: Lagrangian and Hamiltonian approaches

NASA Astrophysics Data System (ADS)

Antonowicz, Marek; Szczyrba, Wiktor

1985-06-01

We consider the SL(2,C)-covariant Lagrangian formulation of gravitational theories with the presence of spinor matter fields. The invariance properties of such theories give rise to the conservation laws (the contracted Bianchi identities) having in the presence of matter fields a more complicated form than those known in the literature previously. A general SL(2,C) gauge theory of gravity is cast into an SL(2,C)-covariant Hamiltonian formulation. Breaking the SL(2,C) symmetry of the system to the SU(2) symmetry, by introducing a spacelike slicing of spacetime, we get an SU(2)-covariant Hamiltonian picture. The qualitative analysis of SL(2,C) gauge theories of gravity in the SU(2)-covariant formulation enables us to define the dynamical symplectic variables and the gauge variables of the theory under consideration as well as to divide the set of field equations into the dynamical equations and the constraints. In the SU(2)-covariant Hamiltonian formulation the primary constraints, which are generic for first-order matter Lagrangians (Dirac, Weyl, Fierz-Pauli), can be reduced. The effective matter symplectic variables are given by SU(2)-spinor-valued half-forms on three-dimensional slices of spacetime. The coupled Einstein-Cartan-Dirac (Weyl, Fierz-Pauli) system is analyzed from the (3+1) point of view. This analysis is complete; the field equations of the Einstein-Cartan-Dirac theory split into 18 gravitational dynamical equations, 8 dynamical Dirac equations, and 7 first-class constraints. The system has 4+8=12 independent degrees of freedom in the phase space.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Célérier, Marie-Noëlle; Nottale, Laurent, E-mail: marie-noelle.celerier@obspm.fr, E-mail: laurent.nottale@obspm.fr

Owing to the non-differentiable nature of the theory of Scale Relativity, the emergence of complex wave functions, then of spinors and bi-spinors occurs naturally in its framework. The wave function is here a manifestation of the velocity field of geodesics of a continuous and non-differentiable (therefore fractal) space-time. In a first paper (Paper I), we have presented the general argument which leads to this result using an elaborate and more detailed derivation than previously displayed. We have therefore been able to show how the complex wave function emerges naturally from the doubling of the velocity field and to revisit themore » derivation of the non-relativistic Schrödinger equation of motion. In the present paper (Paper II), we deal with relativistic motion and detail the natural emergence of the bi-spinors from such first principles of the theory. Moreover, while Lorentz invariance has been up to now inferred from mathematical results obtained in stochastic mechanics, we display here a new and detailed derivation of the way one can obtain a Lorentz invariant expression for the expectation value of the product of two independent fractal fluctuation fields in the sole framework of the theory of Scale Relativity. These new results allow us to enhance the robustness of our derivation of the two main equations of motion of relativistic quantum mechanics (the Klein-Gordon and Dirac equations) which we revisit here at length.« less

Optical Bistability under Nonresonant Excitation in Spinor Polariton Condensates

NASA Astrophysics Data System (ADS)

Pickup, L.; Kalinin, K.; Askitopoulos, A.; Hatzopoulos, Z.; Savvidis, P. G.; Berloff, N. G.; Lagoudakis, P. G.

2018-06-01

We realize bistability in the spinor of polariton condensates under nonresonant optical excitation and in the absence of biasing external fields. Numerical modeling of the system using the Ginzburg-Landau equation with an internal Josephson coupling between the two spin components of the condensate qualitatively describes the experimental observations. We demonstrate that polariton spin bistability strongly depends on the condensate's overlap with the exciton reservoir by tuning the excitation geometry and sample temperature. We obtain noncollapsing bistability hysteresis loops for a record range of sweep times, [10 μ s , 1 s], offering a promising route to spin switches and spin memory elements.

Symmetry operators and decoupled equations for linear fields on black hole spacetimes

NASA Astrophysics Data System (ADS)

Araneda, Bernardo

2017-02-01

In the class of vacuum Petrov type D spacetimes with cosmological constant, which includes the Kerr-(A)dS black hole as a particular case, we find a set of four-dimensional operators that, when composed off shell with the Dirac, Maxwell and linearized gravity equations, give a system of equations for spin weighted scalars associated with the linear fields, that decouple on shell. Using these operator relations we give compact reconstruction formulae for solutions of the original spinor and tensor field equations in terms of solutions of the decoupled scalar equations. We also analyze the role of Killing spinors and Killing-Yano tensors in the spin weight zero equations and, in the case of spherical symmetry, we compare our four-dimensional formulation with the standard 2  +  2 decomposition and particularize to the Schwarzschild-(A)dS black hole. Our results uncover a pattern that generalizes a number of previous results on Teukolsky-like equations and Debye potentials for higher spin fields.

General heat kernel coefficients for massless free spin-3/2 Rarita-Schwinger field

NASA Astrophysics Data System (ADS)

Karan, Sudip; Kumar, Shashank; Panda, Binata

2018-04-01

We review the general heat kernel method for the Dirac spinor field as an elementary example in any arbitrary background. We, then compute the first three Seeley-DeWitt coefficients for the massless free spin-3/2 Rarita-Schwinger field without imposing any limitations on the background geometry.

Optical Bistability under Nonresonant Excitation in Spinor Polariton Condensates.

PubMed

Pickup, L; Kalinin, K; Askitopoulos, A; Hatzopoulos, Z; Savvidis, P G; Berloff, N G; Lagoudakis, P G

2018-06-01

We realize bistability in the spinor of polariton condensates under nonresonant optical excitation and in the absence of biasing external fields. Numerical modeling of the system using the Ginzburg-Landau equation with an internal Josephson coupling between the two spin components of the condensate qualitatively describes the experimental observations. We demonstrate that polariton spin bistability strongly depends on the condensate's overlap with the exciton reservoir by tuning the excitation geometry and sample temperature. We obtain noncollapsing bistability hysteresis loops for a record range of sweep times, [10  μs, 1 s], offering a promising route to spin switches and spin memory elements.

Chiral solitons in spinor polariton rings

NASA Astrophysics Data System (ADS)

Zezyulin, D. A.; Gulevich, D. R.; Skryabin, D. V.; Shelykh, I. A.

2018-04-01

We consider theoretically one-dimensional polariton ring accounting for both longitudinal-transverse (TE-TM) and Zeeman splittings of spinor polariton states and spin-dependent polariton-polariton interactions. We present a class of solutions in the form of the localized defects rotating with constant angular velocity and analyze their properties for realistic values of the parameters of the system. We show that the effects of the geometric phase arising from the interplay between the external magnetic field and the TE-TM splitting introduce chirality in the system and make solitons propagating in clockwise and anticlockwise directions nonequivalent. This can be interpreted as a solitonic analog of the Aharonov-Bohm effect.

Physical renormalization condition for de Sitter QED

NASA Astrophysics Data System (ADS)

Hayashinaka, Takahiro; Xue, She-Sheng

2018-05-01

We considered a new renormalization condition for the vacuum expectation values of the scalar and spinor currents induced by a homogeneous and constant electric field background in de Sitter spacetime. Following a semiclassical argument, the condition named maximal subtraction imposes the exponential suppression on the massive charged particle limit of the renormalized currents. The maximal subtraction changes the behaviors of the induced currents previously obtained by the conventional minimal subtraction scheme. The maximal subtraction is favored for a couple of physically decent predictions including the identical asymptotic behavior of the scalar and spinor currents, the removal of the IR hyperconductivity from the scalar current, and the finite current for the massless fermion.

Killing spinors and related symmetries in six dimensions

NASA Astrophysics Data System (ADS)

Batista, Carlos

2016-03-01

Benefiting from the index spinorial formalism, the Killing spinor equation is integrated in six-dimensional spacetimes. The integrability conditions for the existence of a Killing spinor are worked out and the Killing spinors are classified into two algebraic types; in the first type the scalar curvature of the spacetime must be negative, while in the second type the spacetime must be an Einstein manifold. In addition, the equations that define Killing-Yano (KY) and closed conformal Killing-Yano (CCKY) tensors are expressed in the index notation and, as consequence, all nonvanishing KY and CCKY tensors that can be generated from a Killing spinor are made explicit.

Anomaly-corrected supersymmetry algebra and supersymmetric holographic renormalization

NASA Astrophysics Data System (ADS)

An, Ok Song

2017-12-01

We present a systematic approach to supersymmetric holographic renormalization for a generic 5D N=2 gauged supergravity theory with matter multiplets, including its fermionic sector, with all gauge fields consistently set to zero. We determine the complete set of supersymmetric local boundary counterterms, including the finite counterterms that parameterize the choice of supersymmetric renormalization scheme. This allows us to derive holographically the superconformal Ward identities of a 4D superconformal field theory on a generic background, including the Weyl and super-Weyl anomalies. Moreover, we show that these anomalies satisfy the Wess-Zumino consistency condition. The super-Weyl anomaly implies that the fermionic operators of the dual field theory, such as the supercurrent, do not transform as tensors under rigid supersymmetry on backgrounds that admit a conformal Killing spinor, and their anticommutator with the conserved supercharge contains anomalous terms. This property is explicitly checked for a toy model. Finally, using the anomalous transformation of the supercurrent, we obtain the anomaly-corrected supersymmetry algebra on curved backgrounds admitting a conformal Killing spinor.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Silva, J.M. Hoff da; Pereira, S.H., E-mail: hoff@feg.unesp.br, E-mail: shpereira@gmail.com

In this paper we present exact solutions to the so-called Elko spinors for three models of expanding universe, namely the de Sitter, linear and the radiation type evolution. The study was restricted to flat, homogeneous and isotropic Friedmann-Robertson-Walker backgrounds. Starting with an Elko spinor we present the solutions for these cases and compare to the case of Dirac spinors. Besides, an attempt to use Elko spinors as a dark energy candidate in the cosmological context is investigated.

Symmetry operators of Killing spinors and superalgebras in AdS5

NASA Astrophysics Data System (ADS)

Ertem, Ümit

2016-04-01

We construct the first-order symmetry operators of Killing spinor equation in terms of odd Killing-Yano forms. By modifying the Schouten-Nijenhuis bracket of Killing-Yano forms, we show that the symmetry operators of Killing spinors close into an algebra in AdS5 spacetime. Since the symmetry operator algebra of Killing spinors corresponds to a Jacobi identity in extended Killing superalgebras, we investigate the possible extensions of Killing superalgebras to include higher-degree Killing-Yano forms. We found that there is a superalgebra extension but no Lie superalgebra extension of the Killing superalgebra constructed out of Killing spinors and odd Killing-Yano forms in AdS5 background.

Maxwell–Dirac stress–energy tensor in terms of Fierz bilinear currents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inglis, Shaun, E-mail: sminglis@utas.edu.au; Jarvis, Peter, E-mail: Peter.Jarvis@utas.edu.au

We analyse the stress–energy tensor for the self-coupled Maxwell–Dirac system in the bilinear current formalism, using two independent approaches. The first method used is that attributed to Belinfante: starting from the spinor form of the action, the well-known canonical stress–energy tensor is augmented, by extending the Noether symmetry current to include contributions from the Lorentz group, to a manifestly symmetric form. This form admits a transcription to bilinear current form. The second method used is the variational derivation based on the covariant coupling to general relativity. The starting point here at the outset is the transcription of the action using,more » as independent field variables, both the bilinear currents, together with a gauge invariant vector field (a proxy for the electromagnetic vector potential). A central feature of the two constructions is that they both involve the mapping of the Dirac contribution to the stress–energy from the spinor fields to the equivalent set of bilinear tensor currents, through the use of appropriate Fierz identities. Although this mapping is done at quite different stages, nonetheless we find that the two forms of the bilinear stress–energy tensor agree. Finally, as an application, we consider the reduction of the obtained stress–energy tensor in bilinear form, under the assumption of spherical symmetry. -- Highlights: •Maxwell–Dirac stress–energy tensor derived in manifestly gauge invariant bilinear form. •Dirac spinor Belinfante tensor transcribed to bilinear fields via Fierz mapping. •Variational stress–energy obtained via bilinearized action, in contrast to Belinfante case. •Independent derivations via the Belinfante and variational methods agree, as required. •Spherical symmetry reduction given as a working example for wider applications.« less

Synthetic Landau Levels and Spinor Vortex Matter on a Haldane Spherical Surface with a Magnetic Monopole.

PubMed

Zhou, Xiang-Fa; Wu, Congjun; Guo, Guang-Can; Wang, Ruquan; Pu, Han; Zhou, Zheng-Wei

2018-03-30

We present a flexible scheme to realize exact flat Landau levels on curved spherical geometry in a system of spinful cold atoms. This is achieved by applying the Floquet engineering of a magnetic quadrupole field to create a synthetic monopole field in real space. The system can be exactly mapped to the electron-monopole system on a sphere, thus realizing Haldane's spherical geometry for fractional quantum Hall physics. This method works for either bosons or fermions. We investigate the ground-state vortex pattern for an s-wave interacting atomic condensate by mapping this system to the classical Thompson's problem. The distortion and stability of the vortex pattern are further studied in the presence of dipolar interaction. Our scheme is compatible with the current experimental setup, and may serve as a promising route of investigating quantum Hall physics and exotic spinor vortex matter on curved space.

Strong gravity and structure of topological solitons

NASA Astrophysics Data System (ADS)

Rybakov, Yu. P.

The unification of Skyrme and Faddeev chiral models describing baryons and leptons respectively as topological solitons is suggested within the framework of 16-spinor field ψ = ψ1 ⊕ ψ2 nonlinear model containing two 8-semispinors ψ1 and ψ2. Using Brioschi identity for 8-spinors and special structure of the Higgs potential V implying the spontaneous symmetry breaking, it is possible to realize topological soliton-like excitations of two kinds due to the choice of S2- or S3- manifolds as phase spaces. The interactions with electromagnetic, Yang--Mills and gravitational fields are exhibited through the extention of derivatives via gauge invariance principle. Specific inclusion in the Higgs potential of the Kretschmann gravitational invariant K = RμνσλRμνσλ/48 permits one to obtain the strong gravity behavior at small distances and guarantee the correspondence with Quantum Mechanics at large distances.

Synthetic Landau Levels and Spinor Vortex Matter on a Haldane Spherical Surface with a Magnetic Monopole

NASA Astrophysics Data System (ADS)

Zhou, Xiang-Fa; Wu, Congjun; Guo, Guang-Can; Wang, Ruquan; Pu, Han; Zhou, Zheng-Wei

2018-03-01

We present a flexible scheme to realize exact flat Landau levels on curved spherical geometry in a system of spinful cold atoms. This is achieved by applying the Floquet engineering of a magnetic quadrupole field to create a synthetic monopole field in real space. The system can be exactly mapped to the electron-monopole system on a sphere, thus realizing Haldane's spherical geometry for fractional quantum Hall physics. This method works for either bosons or fermions. We investigate the ground-state vortex pattern for an s -wave interacting atomic condensate by mapping this system to the classical Thompson's problem. The distortion and stability of the vortex pattern are further studied in the presence of dipolar interaction. Our scheme is compatible with the current experimental setup, and may serve as a promising route of investigating quantum Hall physics and exotic spinor vortex matter on curved space.

Soliton Dynamics of an Atomic Spinor Condensate on a Ring Lattice

DTIC Science & Technology

2013-02-22

REPORT Soliton dynamics of an atomic spinor condensate on a Ring Lattice 14. ABSTRACT 16. SECURITY CLASSIFICATION OF: We study the dynamics of...8/98) Prescribed by ANSI Std. Z39.18 - Soliton dynamics of an atomic spinor condensate on a Ring Lattice Report Title ABSTRACT We study the dynamics...Report Number Soliton dynamics of an atomic spinor condensat Block 13: Supplementary Note © 2013 . Published in Physical Review A (accepted), Vol. Ed

Euclidean supersymmetric solutions with the self-dual Weyl tensor

NASA Astrophysics Data System (ADS)

Nozawa, Masato

2017-07-01

We explore the Euclidean supersymmetric solutions admitting the self-dual gauge field in the framework of N = 2 minimal gauged supergravity in four dimensions. According to the classification scheme utilizing the spinorial geometry or the bilinears of Killing spinors, the general solution preserves one quarter of supersymmetry and is described by the Przanowski-Tod class with the self-dual Weyl tensor. We demonstrate that there exists an additional Killing spinor, provided the Przanowski-Tod metric admits a Killing vector that commutes with the principal one. The proof proceeds by recasting the metric into another Przanowski-Tod form. This formalism enables us to show that the self-dual Reissner-Nordström-Taub-NUT-AdS metric possesses a second Killing spinor, which has been missed over many years. We also address the supersymmetry when the Przanowski-Tod space is conformal to each of the self-dual ambi-toric Kähler metrics. It turns out that three classes of solutions are all reduced to the self-dual Carter family, by virtue of the nondegenerate Killing-Yano tensor.

Impulsive spherical gravitational waves

NASA Astrophysics Data System (ADS)

Aliev, A. N.; Nutku, Y.

2001-03-01

Penrose's identification with warp provides the general framework for constructing the continuous form of impulsive gravitational wave metrics. We present the two-component spinor formalism for the derivation of the full family of impulsive spherical gravitational wave metrics which brings out the power in identification with warp and leads to the simplest derivation of exact solutions. These solutions of the Einstein vacuum field equations are obtained by cutting Minkowski space into two pieces along a null cone and re-identifying them with warp which is given by an arbitrary nonlinear holomorphic transformation. Using two-component spinor techniques we construct a new metric describing an impulsive spherical gravitational wave where the vertex of the null cone lies on a worldline with constant acceleration.

A formalism for the calculus of variations with spinors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bäckdahl, Thomas, E-mail: thobac@chalmers.se; Valiente Kroon, Juan A., E-mail: j.a.valiente-kroon@qmul.ac.uk

2016-02-15

We develop a frame and dyad gauge-independent formalism for the calculus of variations of functionals involving spinorial objects. As a part of this formalism, we define a modified variation operator which absorbs frame and spin dyad gauge terms. This formalism is applicable to both the standard spacetime (i.e., SL(2, ℂ)) 2-spinors as well as to space (i.e., SU(2, ℂ)) 2-spinors. We compute expressions for the variations of the connection and the curvature spinors.

Explicitly broken supersymmetry with exactly massless moduli

NASA Astrophysics Data System (ADS)

Dong, Xi; Freedman, Daniel Z.; Zhao, Yue

2016-06-01

The AdS/CFT correspondence is applied to an analogue of the little hierarchy problem in three-dimensional supersymmetric theories. The bulk is governed by a super-gravity theory in which a U(1) × U(1) R-symmetry is gauged by Chern-Simons fields. The bulk theory is deformed by a boundary term quadratic in the gauge fields. It breaks SUSY completely and sources an exactly marginal operator in the dual CFT. SUSY breaking is communicated by gauge interactions to bulk scalar fields and their spinor superpartners. The bulk-to-boundary propagator of the Chern-Simons fields is a total derivative with respect to the bulk coordinates. Integration by parts and the Ward identity permit evaluation of SUSY breaking effects to all orders in the strength of the deformation. The R-charges of scalars and spinors differ so large SUSY breaking mass shifts are generated. Masses of R-neutral particles such as scalar moduli are not shifted to any order in the deformation strength, despite the fact that they may couple to R-charged fields running in loops. We also obtain a universal deformation formula for correlation functions under an exactly marginal deformation by a product of holomorphic and anti-holomorphic U(1) currents.

Dirac equation in 2-dimensional curved spacetime, particle creation, and coupled waveguide arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koke, Christian, E-mail: christian.koke@stud.uni-heidelberg.de; Noh, Changsuk, E-mail: changsuk@kias.re.kr; Angelakis, Dimitris G., E-mail: dimitris.angelakis@gmail.com

When quantum fields are coupled to gravitational fields, spontaneous particle creation may occur similarly to when they are coupled to external electromagnetic fields. A gravitational field can be incorporated as a background spacetime if the back-action of matter on the field can be neglected, resulting in modifications of the Dirac or Klein–Gordon equations for elementary fermions and bosons respectively. The semi-classical description predicts particle creation in many situations, including the expanding-universe scenario, near the event horizon of a black hole (the Hawking effect), and an accelerating observer in flat spacetime (the Unruh effect). In this work, we give a pedagogicalmore » introduction to the Dirac equation in a general 2D spacetime and show examples of spinor wave packet dynamics in flat and curved background spacetimes. In particular, we cover the phenomenon of particle creation in a time-dependent metric. Photonic analogs of these effects are then proposed, where classical light propagating in an array of coupled waveguides provides a visualisation of the Dirac spinor propagating in a curved 2D spacetime background. The extent to which such a single-particle description can be said to mimic particle creation is discussed.« less

Chaos in a 4D dissipative nonlinear fermionic model

NASA Astrophysics Data System (ADS)

Aydogmus, Fatma

2015-12-01

Gursey Model is the only possible 4D conformally invariant pure fermionic model with a nonlinear self-coupled spinor term. It has been assumed to be similar to the Heisenberg's nonlinear generalization of Dirac's equation, as a possible basis for a unitary description of elementary particles. Gursey Model admits particle-like solutions for the derived classical field equations and these solutions are instantonic in character. In this paper, the dynamical nature of damped and forced Gursey Nonlinear Differential Equations System (GNDES) are studied in order to get more information on spinor type instantons. Bifurcation and chaos in the system are observed by constructing the bifurcation diagrams and Poincaré sections. Lyapunov exponent and power spectrum graphs of GNDES are also constructed to characterize the chaotic behavior.

Interaction of non-Abelian tensor gauge fields

NASA Astrophysics Data System (ADS)

Savvidy, George

2018-01-01

The non-Abelian tensor gauge fields take value in extended Poincaré algebra. In order to define the invariant Lagrangian we introduce a vector variable in two alternative ways: through the transversal representation of the extended Poincaré algebra and through the path integral over the auxiliary vector field with the U(1) Abelian action. We demonstrate that this allows to fix the unitary gauge and derive scattering amplitudes in spinor representation.

The interaction of Dirac particles with a Hawking charged radiating black hole

NASA Astrophysics Data System (ADS)

Kubik, Erik

2007-08-01

The interaction of spin 1/2 fields with a charged, evaporating black hole (EBH) is investigated. Using the Vaidya metric to model the Hawking evaporating black hole, the wave equation for a massless spinor field is obtained. The resulting field equation is solved utilizing techniques developed by Brill and Wheeler. Unlike previous efforts, a charged, evaporating black hole has never been used as a background to investigate spin 1/2 quantum field propagation, e.g., Brill and Wheeler considered massless spin 1/2 interactions in a static, Schwarzschild background. Using the WKB approximation, the wave equation is solved for the case of an EBH with constant luminosity. Analysis of the effective potential at different stages of evaporation is made including the dependence on the parameters of the system such as the total angular momentum, energy of the incident field, and luminosity of the evaporating black hole. Utilizing techniques of Mukhopad-hey, the transmission and reflection coefficients for the massless spinors are computed and compared to Schwarzschild result for both the high energy and hard scattering cases. The effect of the time dependence of the space-time metric has an important effect on the behavior of quantum fields over the lifetime of the evaporating black hole and may provide a signature for the detection of such objects.

Spinors fields in co-dimension one braneworlds

NASA Astrophysics Data System (ADS)

Mendes, W. M.; Alencar, G.; Landim, R. R.

2018-02-01

In this work we analyze the zero mode localization and resonances of 1/2-spin fermions in co-dimension one Randall-Sundrum braneworld scenarios. We consider delta-like, domain walls and deformed domain walls membranes. Beyond the influence of the spacetime dimension D we also consider three types of couplings: (i) the standard Yukawa coupling with the scalar field and parameter η 1, (ii) a Yukawa-dilaton coupling with two parameters η 2 and λ and (iii) a dilaton derivative coupling with parameter h. Together with the deformation parameter s, we end up with five free parameter to be considered. For the zero mode we find that the localization is dependent of D, because the spinorial representation changes when the bulk dimensionality is odd or even and must be treated separately. For case (i) we find that in odd dimensions only one chirality can be localized and for even dimension a massless Dirac spinor is trapped over the brane. In the cases (ii) and (iii) we find that for some values of the parameters, both chiralities can be localized in odd dimensions and for even dimensions we obtain that the massless Dirac spinor is trapped over the brane. We also calculated numerically resonances for cases (ii) and (iii) by using the transfer matrix method. We find that, for deformed defects, the increasing of D induces a shift in the peaks of resonances. For a given λ with domain walls, we find that the resonances can show up by changing the spacetime dimensionality. For example, the same case in D = 5 do not induces resonances but when we consider D = 10 one peak of resonance is found. Therefore the introduction of more dimensions, diversely from the bosonic case, can change drastically the zero mode and resonances in fermion fields.

Instabilities in Englert-type supergravity solutions

NASA Astrophysics Data System (ADS)

Page, Don N.; Pope, C. N.

1984-09-01

We show that all eleven-dimensional Englert-type supergravity solutions (in which the four-index field has internal components) constructed from internal spaces M7 having two or more Killing spinors, are unstable. Permanent address: Blackett Laboratory, Imperial College, London SW7 2BZ, United Kingdom.

Improved Apparatus to Study Matter-Wave Quantum Optics in a Sodium Spinor Bose-Einstein Condensate

NASA Astrophysics Data System (ADS)

Zhong, Shan; Bhagat, Anita; Zhang, Qimin; Schwettmann, Arne

2017-04-01

We present and characterize our recently improved experimental apparatus for studying matter-wave quantum optics in spin space in ultracold sodium gases. Improvements include our recent addition of a 3D-printed Helmholtz coil frame for field stabilization and a crossed optical dipole trap. Spin-exchange collisions in the F = 1 spinor Bose-Einstein condensate can be precisely controlled by microwave dressing, and generate pairs of entangled atoms with magnetic quantum numbers mF = + 1 and mF = - 1 from pairs of mF = 0 atoms. Spin squeezing generated by the collisions can reduce the noise of population measurements below the shot noise limit. Versatile microwave pulse sequences will be used to implement an interferometer, a phase-sensitive amplifier and other devices with sub-shot noise performance. With an added ion detector to detect Rydberg atoms via pulse-field ionization, we later plan to study the effect of Rydberg excitations on the spin evolution of the ultracold gas.

Revealing how different spinors can be: The Lounesto spinor classification

NASA Astrophysics Data System (ADS)

Hoff da Silva, J. M.; Cavalcanti, R. T.

2017-11-01

This paper aims to give a coordinate-based introduction to the so-called Lounesto spinorial classification scheme. Among other results, it has evinced classes of spinors which fail to satisfy Dirac equation. The underlying idea and the central aspects of such spinorial categorization are introduced in an argumentative basis, after which we delve into a commented account on recent results obtained from (and within) this branch of research.

Particle localization, spinor two-valuedness, and Fermi quantization of tensor systems

NASA Technical Reports Server (NTRS)

Reifler, Frank; Morris, Randall

1994-01-01

Recent studies of particle localization shows that square-integrable positive energy bispinor fields in a Minkowski space-time cannot be physically distinguished from constrained tensor fields. In this paper we generalize this result by characterizing all classical tensor systems, which admit Fermi quantization, as those having unitary Lie-Poisson brackets. Examples include Euler's tensor equation for a rigid body and Dirac's equation in tensor form.

Spectral flow as a map between N = (2 , 0)-models

NASA Astrophysics Data System (ADS)

Athanasopoulos, P.; Faraggi, A. E.; Gepner, D.

2014-07-01

The space of (2 , 0) models is of particular interest among all heterotic-string models because it includes the models with the minimal SO (10) unification structure, which is well motivated by the Standard Model of particle physics data. The fermionic Z2 ×Z2 heterotic-string models revealed the existence of a new symmetry in the space of string configurations under the exchange of spinors and vectors of the SO (10) GUT group, dubbed spinor-vector duality. In this paper we generalize this idea to arbitrary internal rational conformal field theories (RCFTs). We explain how the spectral flow operator normally acting within a general (2 , 2) theory can be used as a map between (2 , 0) models. We describe the details, give an example and propose more simple currents that can be used in a similar way.

Two-spinor description of massive particles and relativistic spin projection operators

NASA Astrophysics Data System (ADS)

Isaev, A. P.; Podoinitsyn, M. A.

2018-04-01

On the basis of the Wigner unitary representations of the covering group ISL (2 , C) of the Poincaré group, we obtain spin-tensor wave functions of free massive particles with arbitrary spin. The wave functions automatically satisfy the Dirac-Pauli-Fierz equations. In the framework of the two-spinor formalism we construct spin-vectors of polarizations and obtain conditions that fix the corresponding relativistic spin projection operators (Behrends-Fronsdal projection operators). With the help of these conditions we find explicit expressions for relativistic spin projection operators for integer spins (Behrends-Fronsdal projection operators) and then find relativistic spin projection operators for half integer spins. These projection operators determine the numerators in the propagators of fields of relativistic particles. We deduce generalizations of the Behrends-Fronsdal projection operators for arbitrary space-time dimensions D > 2.

Solution to the nonlinear field equations of ten dimensional supersymmetric Yang-Mills theory

NASA Astrophysics Data System (ADS)

Mafra, Carlos R.; Schlotterer, Oliver

2015-09-01

In this paper, we present a formal solution to the nonlinear field equations of ten-dimensional super Yang-Mills theory. It is assembled from products of linearized superfields which have been introduced as multiparticle superfields in the context of superstring perturbation theory. Their explicit form follows recursively from the conformal field theory description of the gluon multiplet in the pure spinor superstring. Furthermore, superfields of higher-mass dimensions are defined and their equations of motion are spelled out.

Matter-antimatter asymmetry and dark matter from torsion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poplawski, Nikodem J.

2011-04-15

We propose a simple scenario which explains the observed matter-antimatter imbalance and the origin of dark matter in the Universe. We use the Einstein-Cartan-Sciama-Kibble theory of gravity which naturally extends general relativity to include the intrinsic spin of matter. Spacetime torsion produced by spin generates, in the classical Dirac equation, the Hehl-Datta term which is cubic in spinor fields. We show that under a charge-conjugation transformation this term changes sign relative to the mass term. A classical Dirac spinor and its charge conjugate therefore satisfy different field equations. Fermions in the presence of torsion have higher energy levels than antifermions,more » which leads to their decay asymmetry. Such a difference is significant only at extremely high densities that existed in the very early Universe. We propose that this difference caused a mechanism, according to which heavy fermions existing in such a Universe and carrying the baryon number decayed mostly to normal matter, whereas their antiparticles decayed mostly to hidden antimatter which forms dark matter. The conserved total baryon number of the Universe remained zero.« less

Weinberg propagator of a massive particle with an arbitrary spin (in Ukrainian)

NASA Astrophysics Data System (ADS)

Zima, V. G.; Fedoruk, S. O.

The transition amplitude is obtained for a free massive particle of an arbitrary spin by calculating the path integral in the index--spinor formulation within the BFV--BRST approach. None renormalizations of the path integral measure were applied. The calculation has given the Weinberg propagator written in the index--free form with the use of an index spinor. The choice of boundary conditions on the index spinor determines holomorphic or antiholomorphic representation for the canonical description of particle/antiparticle spin.

Spinorial Geometry and Supergravity

NASA Astrophysics Data System (ADS)

Gillard, Joe

2006-08-01

In the main part of this thesis, we present the foundations and initial results of the Spinorial Geometry formalism for solving Killing spinor equations. This method can be used for any supergravity theory, although we largely focus on D=11 supergravity. The D=5 case is investigated in an appendix. The exposition provides a comprehensive introduction to the formalism, and contains background material on the complex spin representations which, it is hoped, will provide a useful bridge between the mathematical literature and our methods. Many solutions to the D=11 Killing spinor equations are presented, and the consequences for the spacetime geometry are explored in each case. Also in this thesis, we consider another class of supergravity solutions, namely heterotic string backgrounds with (2,0) world-sheet supersymmetry. We investigate the consequences of taking alpha-prime corrections into account in the field equations, in order to remain consistent with anomaly cancellation, while requiring that spacetime supersymmetry is preserved.

Solitons and rogue waves in spinor Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Li, Sitai; Prinari, Barbara; Biondini, Gino

2018-02-01

We present a general classification of one-soliton solutions as well as families of rogue-wave solutions for F =1 spinor Bose-Einstein condensates (BECs). These solutions are obtained from the inverse scattering transform for a focusing matrix nonlinear Schrödinger equation which models condensates in the case of attractive mean-field interactions and ferromagnetic spin-exchange interactions. In particular, we show that when no background is present, all one-soliton solutions are reducible via unitary transformations to a combination of oppositely polarized solitonic solutions of single-component BECs. On the other hand, we show that when a nonzero background is present, not all matrix one-soliton solutions are reducible to a simple combination of scalar solutions. Finally, by taking suitable limits of all the solutions on a nonzero background we also obtain three families of rogue-wave (i.e., rational) solutions.

Matter rogue waves in an F=1 spinor Bose-Einstein condensate.

PubMed

Qin, Zhenyun; Mu, Gui

2012-09-01

We report new types of matter rogue waves of a spinor (three-component) model of the Bose-Einstein condensate governed by a system of three nonlinearly coupled Gross-Pitaevskii equations. The exact first-order rational solutions containing one free parameter are obtained by means of a Darboux transformation for the integrable system where the mean-field interaction is attractive and the spin-exchange interaction is ferromagnetic. For different choices of the parameter, there exists a variety of different shaped solutions including two peaks in bright rogue waves and four dips in dark rogue waves. Furthermore, by utilizing the relation between the three-component and the one-component versions of the nonlinear Schrödinger equation, we can devise higher-order rational solutions, in which three components have different shapes. In addition, it is noteworthy that dark rogue wave features disappear in the third-order rational solution.

Solitons and rogue waves in spinor Bose-Einstein condensates.

PubMed

Li, Sitai; Prinari, Barbara; Biondini, Gino

2018-02-01

We present a general classification of one-soliton solutions as well as families of rogue-wave solutions for F=1 spinor Bose-Einstein condensates (BECs). These solutions are obtained from the inverse scattering transform for a focusing matrix nonlinear Schrödinger equation which models condensates in the case of attractive mean-field interactions and ferromagnetic spin-exchange interactions. In particular, we show that when no background is present, all one-soliton solutions are reducible via unitary transformations to a combination of oppositely polarized solitonic solutions of single-component BECs. On the other hand, we show that when a nonzero background is present, not all matrix one-soliton solutions are reducible to a simple combination of scalar solutions. Finally, by taking suitable limits of all the solutions on a nonzero background we also obtain three families of rogue-wave (i.e., rational) solutions.

Discrete symmetries in the heterotic-string landscape

NASA Astrophysics Data System (ADS)

Athanasopoulos, P.

2015-07-01

We describe a new type of discrete symmetry that relates heterotic-string models. It is based on the spectral flow operator which normally acts within a general N = (2, 2) model and we use this operator to construct a map between N = (2, 0) models. The landscape of N = (2, 0) models is of particular interest among all heterotic-string models for two important reasons: Firstly, N =1 spacetime SUSY requires (2, 0) superconformal invariance and secondly, models with the well motivated by the Standard Model SO(10) unification structure are of this type. This idea was inspired by a new discrete symmetry in the space of fermionic ℤ2 × ℤ2 heterotic-string models that exchanges the spinors and vectors of the SO(10) GUT group, dubbed spinor-vector duality. We will describe how to generalize this to arbitrary internal rational Conformal Field Theories.

Prethermalized states of quenched spinor condensates

NASA Astrophysics Data System (ADS)

Chakram, Srivatsan; Patil, Yogesh Sharad; Vengalattore, Mukund

2015-05-01

Due to the interplay between spin and charge degrees of freedom, spinor Bose condensates exhibit a rich tapestry of magnetically ordered phases and topological defects. The non-equilibrium properties of these fluids have been the topic of recent interest. We have previously shown that quenched spinor condensates exhibit robust prethermalized states characterized by asymptotic correlations that differ from thermodynamic predictions. These non-equilibrium states arise due to the disparate energy scales between the phonon and magnon excitations. The identification of a microscopic origin of prethermalization makes this system a promising platform for studies of prethermalization and possible universal scaling relations that characterize these nonequilibrium many-body states. We elaborate on our studies of prethermalized spinor condensates and the prospects of observing a dynamical Kosterlitz-Thouless transition in this system. This work is supported by the ARO MURI on non-equilibrium dynamics.

Weinberg propagator of a free massive particle with an arbitrary spin from the BFV-BRST path integral

NASA Astrophysics Data System (ADS)

Zima, V. G.; Fedoruk, S. O.

1999-11-01

The transition amplitude is obtained for a free massive particle of arbitrary spin by calculating the path integral in the index-spinor formulation within the BFV-BRST approach. No renormalizations of the path integral measure were applied. The calculation has given the Weinberg propagator written in the index-free form by the use of an index spinor. The choice of boundary conditions on the index spinor determines the holomorphic or antiholomorphic representation for the canonical description of particle/antiparticle spin.

Change of Electroweak Nuclear Reaction Rates by CP- and Isospin Symmetry Breaking - A Model Calculation

NASA Astrophysics Data System (ADS)

Stumpf, Harald

2006-09-01

Based on the assumption that electroweak bosons, leptons and quarks possess a substructure of elementary fermionic constituents, in previous papers the effect of CP-symmetry breaking on the effective dynamics of these particles was calculated. Motivated by the phenomenological procedure in this paper, isospin symmetry breaking will be added and the physical consequences of these calculations will be discussed. The dynamical law of the fermionic constituents is given by a relativistically invariant nonlinear spinor field equation with local interaction, canonical quantization, selfregularization and probability interpretation. The corresponding effective dynamics is derived by algebraic weak mapping theorems. In contrast to the commonly applied modifications of the quark mass matrices, CP-symmetry breaking is introduced into this algebraic formalism by an inequivalent vacuum with respect to the CP-invariant case, represented by a modified spinor field propagator. This leads to an extension of the standard model as effective theory which contains besides the "electric" electroweak bosons additional "magnetic" electroweak bosons and corresponding interactions. If furthermore the isospin invariance of the propagator is broken too, it will be demonstrated in detail that in combination with CP-symmetry breaking this induces a considerable modification of electroweak nuclear reaction rates.

Effect of Vacuum Properties on Electroweak Processes - A Theoretical Interpretation of Experiments

NASA Astrophysics Data System (ADS)

Stumpf, Harald

2008-06-01

Recently for discharges in fluids induced nuclear transmutations have been observed. It is our hypothesis that these reactions are due to a symmetry breaking of the electroweak vacuum by the experimental arrangement. The treatment of this hypothesis is based on the assumption that electroweak bosons, leptons and quarks possess a substructure of elementary fermionic constituents. The dynamical law of these fermionic constituents is given by a relativistically invariant nonlinear spinor field equation with local interaction, canonical quantization, selfregularization and probability interpretation. Phenomenological quantities of electroweak processes follow from the derivation of corresponding effective theories obtained by algebraic weak mapping theorems where the latter theories depend on the spinor field propagator, i. e. a vacuum expectation value. This propagator and its equation are studied for conserved and for broken discrete symmetries. For combined CP- and isospin symmetry breaking it is shown that the propagator corresponds to the experimental arrangements under consideration. The modifications of the effective electroweak theory due to this modified propagator are discussed. Based on these results a mechanism is sketched which offers a qualitative interpretation of the appearance of induced nuclear transmutations. A numerical estimate of electron capture is given.

Magneto-optical quantum interferences in a system of spinor excitons

NASA Astrophysics Data System (ADS)

Kuan, Wen-Hsuan; Gudmundsson, Vidar

2018-04-01

In this work we investigate magneto-optical properties of two-dimensional semiconductor quantum-ring excitons with Rashba and Dresselhaus spin-orbit interactions threaded by a magnetic flux perpendicular to the plane of the ring. By calculating the excitonic Aharonov-Bohm spectrum, we study the Coulomb and spin-orbit effects on the Aharonov-Bohm features. From the light-matter interactions of the excitons, we find that for scalar excitons, there are open channels for spontaneous recombination resulting in a bright photoluminescence spectrum, whereas the forbidden recombination of dipolar excitons results in a dark photoluminescence spectrum. We investigate the generation of persistent charge and spin currents. The exploration of spin orientations manifests that by adjusting the strength of the spin-orbit interactions, the exciton can be constructed as a squeezed complex with specific spin polarization. Moreover, a coherently moving dipolar exciton acquires a nontrivial dual Aharonov-Casher phase, creating the possibility to generate persistent dipole currents and spin dipole currents. Our study reveals that in the presence of certain spin-orbit generated fields, the manipulation of the magnetic field provides a potential application for quantum-ring spinor excitons to be utilized in nano-scaled magneto-optical switches.

Gauge invariance and infrared divergences in spinor quantum electrodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rello, D.

1984-05-15

We apply to spinor QED a new technique developed by Bergere and Szymanowski in the case of scalar QED. This method expresses QED in terms of a manifestly gauge-independent theory. Moreover, exponentiation of the infrared divergences arises naturally.

Localized nonlinear waves and dynamical stability in spinor Bose–Einstein condensates with time–space modulation

NASA Astrophysics Data System (ADS)

Yao, Yu-Qin; Han, Wei; Li, Ji; Liu, Wu-Ming

2018-05-01

Nonlinearity is one of the most remarkable characteristics of Bose–Einstein condensates (BECs). Much work has been done on one- and two-component BECs with time- or space-modulated nonlinearities, while there is little work on spinor BECs with space–time-modulated nonlinearities. In the present paper we investigate localized nonlinear waves and dynamical stability in spinor Bose–Einstein condensates with nonlinearities dependent on time and space. We solve the three coupled Gross–Pitaevskii equations by similarity transformation and obtain two families of exact matter wave solutions in terms of Jacobi elliptic functions and the Mathieu equation. The localized states of the spinor matter wave describe the dynamics of vector breathing solitons, moving breathing solitons, quasi-breathing solitons and resonant solitons. The results show that one-order vector breathing solitons, quasi-breathing solitons, resonant solitons and the moving breathing solitons ψ ±1 are all stable, but the moving breathing soliton ψ 0 is unstable. We also present the experimental parameters to realize these phenomena in future experiments.

Vortex creation during magnetic trap manipulations of spinor Bose-Einstein condensates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Itin, A. P.; Space Research Institute, RAS, Moscow; Morishita, T.

2006-06-15

We investigate several mechanisms of vortex creation during splitting of a spinor Bose-Einstein condensate (BEC) in a magnetic double-well trap controlled by a pair of current carrying wires and bias magnetic fields. Our study is motivated by a recent MIT experiment on splitting BECs with a similar trap [Y. Shin et al., Phys. Rev. A 72, 021604 (2005)], where an unexpected fork-like structure appeared in the interference fringes indicating the presence of a singly quantized vortex in one of the interfering condensates. It is well known that in a spin-1 BEC in a quadrupole trap, a doubly quantized vortex ismore » topologically produced by a 'slow' reversal of bias magnetic field B{sub z}. Since in the experiment a doubly quantized vortex had never been seen, Shin et al. ruled out the topological mechanism and concentrated on the nonadiabatic mechanical mechanism for explanation of the vortex creation. We find, however, that in the magnetic trap considered both mechanisms are possible: singly quantized vortices can be formed in a spin-1 BEC topologically (for example, during the magnetic field switching-off process). We therefore provide a possible alternative explanation for the interference patterns observed in the experiment. We also present a numerical example of creation of singly quantized vortices due to 'fast' splitting; i.e., by a dynamical (nonadiabatic) mechanism.« less

Dark energy simulacrum in nonlinear electrodynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Labun, Lance; Rafelski, Johann

2010-03-15

Quasiconstant external fields in nonlinear electromagnetism generate a global contribution proportional to g{sup {mu}{nu}}in the energy-momentum tensor, thus a simulacrum of dark energy. To provide a thorough understanding of the origin and strength of its effects, we undertake a complete theoretical and numerical study of the energy-momentum tensor T{sup {mu}{nu}}for nonlinear electromagnetism. The Euler-Heisenberg nonlinearity due to quantum fluctuations of spinor and scalar matter fields is considered and contrasted with the properties of classical nonlinear Born-Infeld electromagnetism. We address modifications of charged particle kinematics by strong background fields.

A perfect spin filtering device through Mach-Zehnder interferometry in a GaAs/AlGaAs electron gas

NASA Astrophysics Data System (ADS)

López, Alexander; Medina, Ernesto; Bolívar, Nelson; Berche, Bertrand

2010-03-01

A spin filtering device based on quantum spin interference is addressed, for use with a two-dimensional GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit (SO) couplings and an applied external magnetic field. We propose an experimentally feasible electronic Mach-Zehnder interferometer and derive a map, in parameter space, that determines perfect spin filtering conditions. We find two broad spin filtering regimes: one where filtering is achieved in the original incoming quantization basis, that takes advantage of the purely non-Abelian nature of the spin rotations; and another where one needs a tilted preferential axis in order to observe the polarized output spinor. Both solutions apply for arbitrary incoming electron polarization and energy, and are only limited in output amplitude by the randomness of the incoming spinor state. Including a full account of the beam splitter and mirror effects on spin yields solutions only for the tilted basis, but encompasses a broad range of filtering conditions.

A perfect spin filtering device through Mach-Zehnder interferometry in a GaAs/AlGaAs electron gas.

PubMed

López, Alexander; Medina, Ernesto; Bolívar, Nelson; Berche, Bertrand

2010-03-24

A spin filtering device based on quantum spin interference is addressed, for use with a two-dimensional GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit (SO) couplings and an applied external magnetic field. We propose an experimentally feasible electronic Mach-Zehnder interferometer and derive a map, in parameter space, that determines perfect spin filtering conditions. We find two broad spin filtering regimes: one where filtering is achieved in the original incoming quantization basis, that takes advantage of the purely non-Abelian nature of the spin rotations; and another where one needs a tilted preferential axis in order to observe the polarized output spinor. Both solutions apply for arbitrary incoming electron polarization and energy, and are only limited in output amplitude by the randomness of the incoming spinor state. Including a full account of the beam splitter and mirror effects on spin yields solutions only for the tilted basis, but encompasses a broad range of filtering conditions.

Lorentz-violating modification of Dirac theory based on spin-nondegenerate operators

NASA Astrophysics Data System (ADS)

Reis, J. A. A. S.; Schreck, M.

2017-04-01

The Standard Model extension (SME) parametrizes all possible Lorentz-violating contributions to the Standard Model and general relativity. It can be considered as an effective framework to describe possible quantum-gravity effects for energies much below the Planck energy. In the current paper, the spin-nondegenerate operators of the SME fermion sector are the focus. The propagators, energies, and solutions to the modified Dirac equation are obtained for several families of coefficients including nonminimal ones. The particle energies and spinors are computed at first order in Lorentz violation and, with the optical theorem, they are shown to be consistent with the propagators. The optical theorem is then also used to derive the matrices formed from a spinor and its Dirac conjugate at all orders in Lorentz violation. The results are the first explicit ones derived for the spin-nondegenerate operators. They will prove helpful for future phenomenological calculations in the SME that rely on the footing of quantum field theory.

Spin-curvature interaction from curved Dirac equation: Application to single-wall carbon nanotubes

NASA Astrophysics Data System (ADS)

Zhang, Kai; Zhang, Erhu; Chen, Huawei; Zhang, Shengli

2017-06-01

The spin-curvature interaction (SCI) and its effects are investigated based on curved Dirac equation. Through the low-energy approximation of curved Dirac equation, the Hamiltonian of SCI is obtained and depends on the geometry and spinor structure of manifold. We find that the curvature can be considered as field strength and couples with spin through Zeeman-like term. Then, we use dimension reduction to derive the local Hamiltonian of SCI for cylinder surface, which implies that the effective Hamiltonian of single-wall carbon nanotubes results from the geometry and spinor structure of lattice and includes two types of interactions: one does not break any symmetries of the lattice and only shifts the Dirac points for all nanotubes, while the other one does and opens the gaps except for armchair nanotubes. At last, analytical expressions of the band gaps and the shifts of their positions induced by curvature are given for metallic nanotubes. These results agree well with experiments and can be verified experimentally.

Field theory of hyperfluid

NASA Astrophysics Data System (ADS)

Ariki, Taketo

2018-02-01

A hyperfluid model is constructed on the basis of its action entirely free from external constraints, regarding the hyperfluid as a self-consistent classical field. Intrinsic hypermomentum is no longer a supplemental variable given by external constraints, but arises purely from the diffeomorphism covariance of dynamical field. The field-theoretic approach allows natural classification of a hyperfluid on the basis of its symmetry group and corresponding homogeneous space; scalar, spinor, vector, and tensor fluids are introduced as simple examples. Apart from phenomenological constraints, the theory predicts the hypermomentum exchange of fluid via field-theoretic interactions of various classes; fluid–fluid interactions, minimal and non-minimal SU(n) -gauge couplings, and coupling with metric-affine gravity are all successfully formulated within the classical regime.

Vacuum polarization of the quantized massive fields in Friedman-Robertson-Walker spacetime

NASA Astrophysics Data System (ADS)

Matyjasek, Jerzy; Sadurski, Paweł; Telecka, Małgorzata

2014-04-01

The stress-energy tensor of the quantized massive fields in a spatially open, flat, and closed Friedman-Robertson-Walker universe is constructed using the adiabatic regularization (for the scalar field) and the Schwinger-DeWitt approach (for the scalar, spinor, and vector fields). It is shown that the stress-energy tensor calculated in the sixth adiabatic order coincides with the result obtained from the regularized effective action, constructed from the heat kernel coefficient a3. The behavior of the tensor is examined in the power-law cosmological models, and the semiclassical Einstein field equations are solved exactly in a few physically interesting cases, such as the generalized Starobinsky models.

Path-integral representation for the relativistic particle propagators and BFV quantization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fradkin, E.S.; Gitman, D.M.

1991-11-15

The path-integral representations for the propagators of scalar and spinor fields in an external electromagnetic field are derived. The Hamiltonian form of such expressions can be interpreted in the sense of Batalin-Fradkin-Vilkovisky quantization of one-particle theory. The Lagrangian representation as derived allows one to extract in a natural way the expressions for the corresponding gauge-invariant (reparametrization- and supergauge-invariant) actions for pointlike scalar and spinning particles. At the same time, the measure and ranges of integrations, admissible gauge conditions, and boundary conditions can be exactly established.

Dipolar and spinor bosonic systems

NASA Astrophysics Data System (ADS)

Yukalov, V. I.

2018-05-01

The main properties and methods of describing dipolar and spinor atomic systems, composed of bosonic atoms or molecules, are reviewed. The general approach for the correct treatment of Bose-condensed atomic systems with nonlocal interaction potentials is explained. The approach is applied to Bose-condensed systems with dipolar interaction potentials. The properties of systems with spinor interaction potentials are described. Trapped atoms and atoms in optical lattices are considered. Effective spin Hamiltonians for atoms in optical lattices are derived. The possibility of spintronics with cold atom is emphasized. The present review differs from the previous review articles by concentrating on a thorough presentation of basic theoretical points, helping the reader to better follow mathematical details and to make clearer physical conclusions.

Interfering with the neutron spin

NASA Astrophysics Data System (ADS)

Wagh, Apoorva G.; Rakhecha, Veer Chand

2004-07-01

Charge neutrality, a spin frac{1}{2} and an associated magnetic moment of the neu- tron make it an ideal probe of quantal spinor evolutions. Polarized neutron interferometry in magnetic field Hamiltonians has thus scored several firsts such as direct verification of Pauli anticommutation, experimental separation of geometric and dynamical phases and observation of non-cyclic amplitudes and phases. This paper provides a flavour of the physics learnt from such experiments.

Worldline approach to helicity flip in plane waves

NASA Astrophysics Data System (ADS)

Ilderton, Anton; Torgrimsson, Greger

2016-04-01

We apply worldline methods to the study of vacuum polarization effects in plane wave backgrounds, in both scalar and spinor QED. We calculate helicity-flip probabilities to one loop order and treated exactly in the background field, and provide a toolkit of methods for use in investigations of higher-order processes. We also discuss the connections between the worldline, S-matrix, and lightfront approaches to vacuum polarization effects.

Gravitational form factors and decoupling in 2D

NASA Astrophysics Data System (ADS)

Ribeiro, Tiago G.; Shapiro, Ilya L.; Zanusso, Omar

2018-07-01

We calculate and analyse non-local gravitational form factors induced by quantum matter fields in curved two-dimensional space. The calculations are performed for scalars, spinors and massive vectors by means of the covariant heat kernel method up to the second order in the curvature and confirmed using Feynman diagrams. The analysis of the ultraviolet (UV) limit reveals a generalized "running" form of the Polyakov action for a nonminimal scalar field and the usual Polyakov action in the conformally invariant cases. In the infrared (IR) we establish the gravitational decoupling theorem, which can be seen directly from the form factors or from the physical beta function for fields of any spin.

Harmonic spinors on a family of Einstein manifolds

NASA Astrophysics Data System (ADS)

Franchetti, Guido

2018-06-01

The purpose of this paper is to study harmonic spinors defined on a 1-parameter family of Einstein manifolds which includes Taub–NUT, Eguchi–Hanson and with the Fubini–Study metric as particular cases. We discuss the existence of and explicitly solve for spinors harmonic with respect to the Dirac operator twisted by a geometrically preferred connection. The metrics examined are defined, for generic values of the parameter, on a non-compact manifold with the topology of and extend to as edge-cone metrics. As a consequence, the subtle boundary conditions of the Atiyah–Patodi–Singer index theorem need to be carefully considered in order to show agreement between the index of the twisted Dirac operator and the result obtained by counting the explicit solutions.

Dirac Theory on a Space with Linear Lie Type Fuzziness

NASA Astrophysics Data System (ADS)

Shariati, Ahmad; Khorrami, Mohammad; Fatollahi, Amir H.

2012-08-01

A spinor theory on a space with linear Lie type noncommutativity among spatial coordinates is presented. The model is based on the Fourier space corresponding to spatial coordinates, as this Fourier space is commutative. When the group is compact, the real space exhibits lattice characteristics (as the eigenvalues of space operators are discrete), and the similarity of such a lattice with ordinary lattices is manifested, among other things, in a phenomenon resembling the famous fermion doubling problem. A projection is introduced to make the dynamical number of spinors equal to that corresponding to the ordinary space. The actions for free and interacting spinors (with Fermi-like interactions) are presented. The Feynman rules are extracted and 1-loop corrections are investigated.

Front-form spinors in the Weinberg-Soper formalism and generalized Melosh transformations for any spin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahluwalia, D.V.; Sawicki, M.

Using the Weinberg-Soper formalism we construct the front-form ([ital j],0)[direct sum](0,[ital j]) spinors. Explicit expressions for the generalized Melosh transformations up to spin two are obtained. The formalism, without explicitly invoking any wave equations, reproduces the spin-1/2 front-form results of Melosh, Lepage and Brodsky, and Dziembowski.

Spinor driven cosmic bounces and their cosmological perturbations

NASA Astrophysics Data System (ADS)

Farnsworth, Shane; Lehners, Jean-Luc; Qiu, Taotao

2017-10-01

When coupling fermions to gravity, torsion is naturally induced. We consider the possibility that fermion bilinears can act as a source for torsion, altering the dynamics of the early universe such that the big bang gets replaced with a classical nonsingular bounce. We extend previous studies in several ways: we allow more general fermion couplings, consider both commuting and anticommuting spinors, and demonstrate that with an appropriate choice of potential one can easily obtain essentially arbitrary equations of state, including violations of the null energy condition, as required for a bounce. As an example, we construct a model of ekpyrotic contraction followed by a nonsingular bounce into an expanding phase. We analyze cosmological fluctuations in these models, and show that the perturbations can be rewritten in real fluid form. We find indications that spinor bounces are stable, and exhibit several solutions for the perturbations. Interestingly, spinor models do not admit a scalar-vector-tensor decomposition, and consequently some types of scalar fluctuations can act as a source for gravitational waves already at linear order. We also find that the first order dynamics are directionally dependent, an effect which might lead to distinguished observational signatures.

Multi-second magnetic coherence in a single domain spinor Bose–Einstein condensate

NASA Astrophysics Data System (ADS)

Palacios, Silvana; Coop, Simon; Gomez, Pau; Vanderbruggen, Thomas; Natali Martinez de Escobar, Y.; Jasperse, Martijn; Mitchell, Morgan W.

2018-05-01

We describe a compact, robust and versatile system for studying the macroscopic spin dynamics in a spinor Bose–Einstein condensate. Condensates of {}87{Rb} are produced by all-optical evaporation in a 1560 nm optical dipole trap, using a non-standard loading sequence that employs an ancillary 1529 nm beam for partial compensation of the strong differential light-shift induced by the dipole trap itself. We use near-resonant Faraday rotation probing to non-destructively track the condensate magnetization, and demonstrate few-Larmor-cycle tracking with no detectable degradation of the spin polarization. In the ferromagnetic F = 1 ground state, we observe the spin orientation between atoms in the condensate is preserved, such that they precess all together like one large spin in the presence of a magnetic field. We characterize this dynamics in terms of the single-shot magnetic coherence times {{ \\mathcal T }}1 and {{ \\mathcal T }}2* , and observe them to be of several seconds, limited only by the residence time of the atoms in the trap. At the densities used, this residence is restricted only by one-body losses set by the vacuum conditions.

Matter rogue waves for the three-component Gross-Pitaevskii equations in the spinor Bose-Einstein condensates.

PubMed

Sun, Wen-Rong; Wang, Lei

2018-01-01

To show the existence and properties of matter rogue waves in an F =1 spinor Bose-Einstein condensate (BEC), we work on the three-component Gross-Pitaevskii (GP) equations. Via the Darboux-dressing transformation, we obtain a family of rational solutions describing the extreme events, i.e. rogue waves. This family of solutions includes bright-dark-bright and bright-bright-bright rogue waves. The algebraic construction depends on Lax matrices and their Jordan form. The conditions for the existence of rogue wave solutions in an F =1 spinor BEC are discussed. For the three-component GP equations, if there is modulation instability, it is of baseband type only, confirming our analytic conditions. The energy transfers between the waves are discussed.

Matter rogue waves for the three-component Gross-Pitaevskii equations in the spinor Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Sun, Wen-Rong; Wang, Lei

2018-01-01

To show the existence and properties of matter rogue waves in an F=1 spinor Bose-Einstein condensate (BEC), we work on the three-component Gross-Pitaevskii (GP) equations. Via the Darboux-dressing transformation, we obtain a family of rational solutions describing the extreme events, i.e. rogue waves. This family of solutions includes bright-dark-bright and bright-bright-bright rogue waves. The algebraic construction depends on Lax matrices and their Jordan form. The conditions for the existence of rogue wave solutions in an F=1 spinor BEC are discussed. For the three-component GP equations, if there is modulation instability, it is of baseband type only, confirming our analytic conditions. The energy transfers between the waves are discussed.

Argand-plane vorticity singularities in complex scalar optical fields: an experimental study using optical speckle.

PubMed

Rothschild, Freda; Bishop, Alexis I; Kitchen, Marcus J; Paganin, David M

2014-03-24

The Cornu spiral is, in essence, the image resulting from an Argand-plane map associated with monochromatic complex scalar plane waves diffracting from an infinite edge. Argand-plane maps can be useful in the analysis of more general optical fields. We experimentally study particular features of Argand-plane mappings known as "vorticity singularities" that are associated with mapping continuous single-valued complex scalar speckle fields to the Argand plane. Vorticity singularities possess a hierarchy of Argand-plane catastrophes including the fold, cusp and elliptic umbilic. We also confirm their connection to vortices in two-dimensional complex scalar waves. The study of vorticity singularities may also have implications for higher-dimensional fields such as coherence functions and multi-component fields such as vector and spinor fields.

Spacetimes with Killing tensors. [for Einstein-Maxwell fields with certain spinor indices

NASA Technical Reports Server (NTRS)

Hughston, L. P.; Sommers, P.

1973-01-01

The characteristics of the Killing equation and the Killing tensor are discussed. A conformal Killing tensor is of interest inasmuch as it gives rise to a quadratic first integral for null geodesic orbits. The Einstein-Maxwell equations are considered together with the Bianchi identity and the conformal Killing tensor. Two examples for the application of the considered relations are presented, giving attention to the charged Kerr solution and the charged C-metric.

Inconsistency of topologically massive hypergravity

NASA Technical Reports Server (NTRS)

Aragone, C.; Deser, S.

1985-01-01

The coupled topologically massive spin-5/2 gravity system in D = 3 dimensions whose kinematics represents dynamical propagating gauge invariant massive spin-5/2 and spin-2 excitations, is shown to be inconsistent, or equivalently, not locally hypersymmetric. In contrast to D = 4, the local constraints on the system arising from failure of the fermionic Bianchi identities do not involve the 'highest spin' components of the field, but rather the auxiliary spinor required to construct a consistent massive model.

Bose-Fermi mapping and a multibranch spin-chain model for strongly interacting quantum gases in one dimension: Dynamics and collective excitations

NASA Astrophysics Data System (ADS)

Yang, Li; Pu, Han

2016-09-01

We show that the wave function in one spatial sector x1

Non-destructive imaging of spinor Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Samson, E.; Vinit, Anshuman; Raman, Chandra

2013-05-01

We present a non-destructive differential imaging technique that enables the observation of the spatial distribution of the magnetization in a spinor Bose-Einstein condensate (BEC) through a Faraday rotation protocol. In our procedure, we utilize a linearly polarized, far-detuned laser beam as our imaging probe, and upon interaction with the condensate, the beam's polarization direction undergoes Faraday rotation. A differential measurement of the orthogonal polarization components of the rotated beam provides a spatial map of the net magnetization density within the BEC. The non-destructive aspect of this method allows for continuous imaging of the condensate. This imaging technique will prove useful in experimental BEC studies, such as spatially resolved magnetometry using ultracold atoms, and non-destructive imaging of non-equilibrium behavior of antiferromagnetic spinor condensates. This work was supported by the DARPA QuASAR program through a grant from ARO.

Superluminal tunneling of a relativistic half-integer spin particle through a potential barrier

NASA Astrophysics Data System (ADS)

Nanni, Luca

2017-11-01

This paper investigates the problem of a relativistic Dirac half-integer spin free particle tunneling through a rectangular quantum-mechanical barrier. If the energy difference between the barrier and the particle is positive, and the barrier width is large enough, there is proof that the tunneling may be superluminal. For first spinor components of particle and antiparticle states, the tunneling is always superluminal regardless the barrier width. Conversely, the second spinor components of particle and antiparticle states may be either subluminal or superluminal depending on the barrier width. These results derive from studying the tunneling time in terms of phase time. For the first spinor components of particle and antiparticle states, it is always negative while for the second spinor components of particle and antiparticle states, it is always positive, whatever the height and width of the barrier. In total, the tunneling time always remains positive for particle states while it becomes negative for antiparticle ones. Furthermore, the phase time tends to zero, increasing the potential barrier both for particle and antiparticle states. This agrees with the interpretation of quantum tunneling that the Heisenberg uncertainty principle provides. This study's results are innovative with respect to those available in the literature. Moreover, they show that the superluminal behaviour of particles occurs in those processes with high-energy confinement.

Classical field configurations and infrared slavery

NASA Astrophysics Data System (ADS)

Swanson, Mark S.

1987-09-01

The problem of determining the energy of two spinor particles interacting through massless-particle exchange is analyzed using the path-integral method. A form for the long-range interaction energy is obtained by analyzing an abridged vertex derived from the parent theory. This abridged vertex describes the radiation of zero-momentum particles by pointlike sources. A path-integral formalism for calculating the energy of the radiation field associated with this abridged vertex is developed and applications are made to determine the energy necessary for adiabatic separation of two sources in quantum electrodynamics and for an SU(2) Yang-Mills theory. The latter theory is shown to be consistent with confinement via infrared slavery.

An analytic superfield formalism for tree superamplitudes in D=10 and D=11

NASA Astrophysics Data System (ADS)

Bandos, Igor

2018-05-01

Tree amplitudes of 10D supersymmetric Yang-Mills theory (SYM) and 11D supergravity (SUGRA) are collected in multi-particle counterparts of analytic on-shell superfields. These have essentially the same form as their chiral 4D counterparts describing N=4 SYM and N=8 SUGRA, but with components dependent on a different set of bosonic variables. These are the D=10 and D=11 spinor helicity variables, the set of which includes the spinor frame variable (Lorentz harmonics) and a scalar density, and generalized homogeneous coordinates of the coset SO(D-2)/SO(D-4)⊗ U(1) (internal harmonics). We present an especially convenient parametrization of the spinor harmonics (Lorentz covariant gauge fixed with the use of an auxiliary gauge symmetry) and use this to find (a gauge fixed version of) the 3-point tree superamplitudes of 10D SYM and 11D SUGRA which generalize the 4 dimensional anti-MHV superamplitudes.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Requerey, Iker S.; Cobo, B. Ruiz; Iniesta, J. C. Del Toro

We study the dynamics and topology of an emerging magnetic flux concentration using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperiment on board the sunrise balloon-borne solar observatory. We obtain the full vector magnetic field and the line of sight (LOS) velocity through inversions of the Fe i line at 525.02 nm with the SPINOR code. The derived vector magnetic field is used to trace magnetic field lines. Two magnetic flux concentrations with different polarities and LOS velocities are found to be connected by a group of arch-shaped magnetic field lines. The positive polarity footpoint is weakermore » (1100 G) and displays an upflow, while the negative polarity footpoint is stronger (2200 G) and shows a downflow. This configuration is naturally interpreted as a siphon flow along an arched magnetic flux tube.« less

Spin connection as Lorentz gauge field in Fairchild’s action

NASA Astrophysics Data System (ADS)

Cianfrani, Francesco; Montani, Giovanni; Scopelliti, Vincenzo

2016-06-01

We propose a modified gravitational action containing besides the Einstein-Cartan term some quadratic contributions resembling the Yang-Mills Lagrangian for the Lorentz spin connections. We outline how a propagating torsion arises and we solve explicitly the linearized equations of motion on a Minkowski background. We identify among torsion components six degrees of freedom: one is carried by a pseudo-scalar particle, five by a tachyon field. By adding spinor fields and neglecting backreaction on the geometry, we point out how only the pseudo-scalar particle couples directly with fermions, but the resulting coupling constant is suppressed by the ratio between fermion and Planck masses. Including backreaction, we demonstrate how the tachyon field provides causality violation in the matter sector, via an interaction mediated by gravitational waves.

Three-dimensional vortex-bright solitons in a spin-orbit-coupled spin-1 condensate

NASA Astrophysics Data System (ADS)

Gautam, Sandeep; Adhikari, S. K.

2018-01-01

We demonstrate stable and metastable vortex-bright solitons in a three-dimensional spin-orbit-coupled three-component hyperfine spin-1 Bose-Einstein condensate (BEC) using numerical solution and variational approximation of a mean-field model. The spin-orbit coupling provides attraction to form vortex-bright solitons in both attractive and repulsive spinor BECs. The ground state of these vortex-bright solitons is axially symmetric for weak polar interaction. For a sufficiently strong ferromagnetic interaction, we observe the emergence of a fully asymmetric vortex-bright soliton as the ground state. We also numerically investigate moving solitons. The present mean-field model is not Galilean invariant, and we use a Galilean-transformed mean-field model for generating the moving solitons.

All-optical spinor Bose-Einstein condensation and the spinor dynamics-driven atom laser

NASA Astrophysics Data System (ADS)

Lundblad, Nathan Eric

Optical trapping as a viable means of exploring the physics of ultracold dilute atomic gases has revealed a new spectrum of physical phenomena. In particular, macroscopic and sudden occupation of the ground state below a critical temperature---a phenomenon known as Bose-Einstein condensation---has become an even richer system for the study of quantum mechanics, ultracold collisions, and many-body physics in general. Optical trapping liberates the spin degree of the BEC, making the order parameter vectorial ('spinor BEC'), as opposed to the scalar order of traditional magnetically trapped condensates. The work described within is divided into two main efforts. The first encompasses the all-optical creation of a Bose-Einstein condensate in rubidium vapor. An all-optical path to spinor BEC (as opposed to transfer to an optical trap from a magnetic trap condensate) was desired both for the simplicity of the experimental setup and also for the potential gains in speed of creation; evaporative cooling, the only known path to dilute-gas condensation, works only as efficiently as the rate of elastic collisions in the gas, a rate that starts out much higher in optical traps. The first all-optical BEC was formed elsewhere in 2001; the years following saw many groups worldwide seeking to create their own version. Our own all-optical spinor BEC, made with a single-beam dipole trap formed by a focused CO2 laser, is described here, with particular attention paid to trap loading, measurement of trap parameters, and the use of a novel 780 nm high-power laser system. The second part describes initial experiments performed with the nascent condensate. The spinor properties of the condensate are documented, and a measurement is made of the density-dependent rate of spin mixing in the condensate. In addition, we demonstrate a novel dual-beam atom laser formed by outcoupling oppositely polarized components of the condensate, whose populations have been coherently evolved through spin dynamics. We drive coherent spin-mixing evolution through adiabatic compression of the initially weak trap. Such dual beams, nominally number-correlated through the angular momentum-conserving collision 2m0 ⇋ m+1 + m-1 have been proposed as tools to explore entanglement and squeezing in Bose-Einstein condensates.

Superspace models for S-3

NASA Astrophysics Data System (ADS)

McKeon, D. G. C.

2003-11-01

The simplest supersymmetric extension of the group SO(4) is discussed. The superalgebra is realized in a superspace whose Bosonic subspace is the surface of a sphere S-3 embedded in four-dimensional Euclidean space. By using Fermionic coordinates in this superspace, which are chiral symplectic Majorana spinors, it proves possible to devise superfield models involving a complex scalar, a pair of chiral symplectic Majorana spinors, and a complex auxiliary scalar. Kinetic terms involve operators that are isometry generators on S-3.

The 2(2S + 1)-formalism and its connection with other descriptions

NASA Astrophysics Data System (ADS)

Dvoeglazov, Valeriy V.

2016-02-01

In the framework of the Joos-Weinberg 2(2S + 1)-theory for massless particles, the dynamical invariants have been derived from the Lagrangian density which is considered to be a 4-vector. A la Majorana interpretation of the 6-component “spinors”, the field operators of S = 1 particles, as the left- and right-circularly polarized radiation, leads us to the conserved quantities which are analogous to those obtained by Lipkin and Sudbery. The scalar Lagrangian of the Joos-Weinberg theory is shown to be equivalent to the Lagrangian of a free massless field, introduced by Hayashi. As a consequence of a new “gauge” invariance this skew-symmetric field describes physical particles with the longitudinal components only. The interaction of the spinor field with the Weinberg’s 2(2S + 1)-component massless field is considered. New interpretation of the Weinberg field function is proposed.

Nonstandard Dirac equations for nonstandard spinors

NASA Astrophysics Data System (ADS)

Nikitin, A. G.

2014-11-01

Generalized Dirac equation with operator mass term is presented. Its solutions are nonstandard spinors (NSS) which, like eigenspinoren des Ladungskonjugationsoperators (ELKO), are eigenvectors of the charge conjugation and dual-helicity operators. It is demonstrated that in spite of their noncovariant nature the NSS can serve as a carrier space of a representation of Poincaré group. However, the corresponding boost generators are not manifestly covariant and generate nonlocal momentum dependent transformations, which are presented explicitly. These results can present a new look on group-theoretical grounds of ELKO theories.

Infinite tension limit of the pure spinor superstring

NASA Astrophysics Data System (ADS)

Berkovits, Nathan

2014-03-01

Mason and Skinner recently constructed a chiral infinite tension limit of the Ramond-Neveu-Schwarz superstring which was shown to compute the Cachazo-He-Yuan formulae for tree-level d = 10 Yang-Mills amplitudes and the NS-NS sector of tree-level d = 10 supergravity amplitudes. In this letter, their chiral infinite tension limit is generalized to the pure spinor superstring which computes a d = 10 superspace version of the Cachazo-He-Yuan formulae for tree-level d = 10 super-Yang-Mills and supergravity amplitudes.

Spinor Geometry and Signal Transmission in Three-Space

NASA Astrophysics Data System (ADS)

Binz, Ernst; Pods, Sonja; Schempp, Walter

2002-09-01

For a singularity free gradient field in an open set of an oriented Euclidean space of dimension three we define a natural principal bundle out of an immanent complex line bundle. The elements of both bundles are called internal variables. Several other natural bundles are associated with the principal bundle and, in turn, determine the vector field. Two examples are given and it is shown that for a constant vector field circular polarized waves travelling along a field line can be considered as waves of internal variables. Einstein's equation epsilon = m [middle dot] c2 is derived from the geometry of the principal bundle. On SU(2) a relation between spin representations and Schrodinger representations is established. The link between the spin 1/2-model and the Schrodinger representations yields a connection between a microscopic and a macroscopic viewpoint.

A lattice approach to spinorial quantum gravity

NASA Technical Reports Server (NTRS)

Renteln, Paul; Smolin, Lee

1989-01-01

A new lattice regularization of quantum general relativity based on Ashtekar's reformulation of Hamiltonian general relativity is presented. In this form, quantum states of the gravitational field are represented within the physical Hilbert space of a Kogut-Susskind lattice gauge theory. The gauge field of the theory is a complexified SU(2) connection which is the gravitational connection for left-handed spinor fields. The physical states of the gravitational field are those which are annihilated by additional constraints which correspond to the four constraints of general relativity. Lattice versions of these constraints are constructed. Those corresponding to the three-dimensional diffeomorphism generators move states associated with Wilson loops around on the lattice. The lattice Hamiltonian constraint has a simple form, and a correspondingly simple interpretation: it is an operator which cuts and joins Wilson loops at points of intersection.

Internal structure of vortices in a dipolar spinor Bose-Einstein condensate

NASA Astrophysics Data System (ADS)

Borgh, Magnus O.; Lovegrove, Justin; Ruostekoski, Janne

2017-04-01

We demonstrate how dipolar interactions (DI) can have pronounced effects on the structure of vortices in atomic spinor Bose-Einstein condensates and illustrate generic physical principles that apply across dipolar spinor systems. We then find and analyze the cores of singular non-Abelian vortices in a spin-3 52Cr condensate. Using a simpler spin-1 model system, we analyze the underlying dipolar physics and show how a dipolar healing length interacts with the hierarchy of healing lengths of the contact interaction and leads to simple criteria for the core structure: vortex core size is restricted to the shorter spin-dependent healing length when the interactions both favor the ground-state spin condition, but can conversely be enlarged by DI when interactions compete. We further demonstrate manifestations of spin-ordering induced by the DI anisotropy, including DI-dependent angular momentum of nonsingular vortices, as a result of competition with adaptation to rotation, and potentially observable internal vortex-core spin textures. We acknowledge financial support from the EPSRC.

Implications of Higgs Universality for neutrinos

NASA Astrophysics Data System (ADS)

Stephenson, Gerard; Goldman, T.

2017-09-01

Higgs Universality means that the right-chiral Weyl spinors of each charge type couple universally to the Higgs doublet-left-chiral Weyl spinor weak singlets for quarks in the current basis,so the quark mass matrices are of the pairing form. We have shown that the known quark masses and weak current mixing can be recovered by invoking perturbative BSM corrections. The application to the charged leptons is immediate. Assuming the charged fermion-like mass terms for the neutrinos have a similar structure, but that Majorana mass terms for the sterile right-chiral spinors (which qualify as dark matter) must also be included, we show that the ratios of the resulting sterile neutrino masses vary as the square of the ratios of the charged fermion masses. The results are consistent with short-baseline neutrino oscillation experiments. Using that scale, we predict sterile neutrinos at masses of several keV/c2 and some tens of MeV /c2 , which may decay to a photon and a lighter neutrino.

3 parton production at DIS at small x

NASA Astrophysics Data System (ADS)

Hentschinski, Martin

2018-01-01

We use the spinor helicity formalism to calculate the cross section for production of three partons of a given polarization in Deep Inelastic Scattering (DIS) off proton and nucleus targets at small Bjorken x. The target proton or nucleus is treated as a classical color field (shock wave) from which the produced partons scatter multiple times. The resulting expressions are used to study azimuthal angular correlations between produced partons in order to probe the gluon structure of the target hadron or nucleus as well as to study energy loss in DIS reactions.

Positive spaces, generalized semi-densities, and quantum interactions

NASA Astrophysics Data System (ADS)

Canarutto, Daniel

2012-03-01

The basics of quantum particle physics on a curved Lorentzian background are expressed in a formulation which has original aspects and exploits some non-standard mathematical notions. In particular, positive spaces and generalized semi-densities (in a distributional sense) are shown to link, in a natural way, discrete multi-particle spaces to distributional bundles of quantum states. The treatment of spinor and boson fields is partly original also from an algebraic point of view and suggests a non-standard approach to quantum interactions. The case of electroweak interactions provides examples.

Effective description of general extensions of the Standard Model: the complete tree-level dictionary

NASA Astrophysics Data System (ADS)

de Blas, J.; Criado, J. C.; Pérez-Victoria, M.; Santiago, J.

2018-03-01

We compute all the tree-level contributions to the Wilson coefficients of the dimension-six Standard-Model effective theory in ultraviolet completions with general scalar, spinor and vector field content and arbitrary interactions. No assumption about the renormalizability of the high-energy theory is made. This provides a complete ultraviolet/infrared dictionary at the classical level, which can be used to study the low-energy implications of any model of interest, and also to look for explicit completions consistent with low-energy data.

A power-law coupled three-form dark energy model

NASA Astrophysics Data System (ADS)

Yao, Yan-Hong; Yan, Yang-Jie; Meng, Xin-He

2018-02-01

We consider a field theory model of coupled dark energy which treats dark energy as a three-form field and dark matter as a spinor field. By assuming the effective mass of dark matter as a power-law function of the three-form field and neglecting the potential term of dark energy, we obtain three solutions of the autonomous system of evolution equations, including a de Sitter attractor, a tracking solution and an approximate solution. To understand the strength of the coupling, we confront the model with the latest Type Ia Supernova, Baryon Acoustic Oscillations and Cosmic Microwave Background radiation observations, with the conclusion that the combination of these three databases marginalized over the present dark matter density parameter Ω _{m0} and the present three-form field κ X0 gives stringent constraints on the coupling constant, - 0.017< λ <0.047 (2σ confidence level), by which we present the model's applicable parameter range.

Covariant spinor representation of iosp(d,2/2) and quantization of the spinning relativistic particle

NASA Astrophysics Data System (ADS)

Jarvis, P. D.; Corney, S. P.; Tsohantjis, I.

1999-12-01

A covariant spinor representation of iosp(d,2/2) is constructed for the quantization of the spinning relativistic particle. It is found that, with appropriately defined wavefunctions, this representation can be identified with the state space arising from the canonical extended BFV-BRST quantization of the spinning particle with admissible gauge fixing conditions after a contraction procedure. For this model, the cohomological determination of physical states can thus be obtained purely from the representation theory of the iosp(d,2/2) algebra.

Generalized Equations and Their Solutions in the (S, 0) ⊕ (0, S) Representations of the Lorentz Group

NASA Astrophysics Data System (ADS)

Dvoeglazov, V. V.

2017-05-01

We present three explicit examples of generalizations in relativistic quantum mechanics. First of all, we discuss the generalized spin-1/2 equations for neutrinos. They have been obtained by means of the Gersten-Sakurai method for derivations of arbitrary-spin relativistic equations. Possible physical consequences are discussed. Next, it is easy to check that both Dirac algebraic equation {Det}(\\hat{p}-m)=0 and {Det}(\\hat{p}+m)=0 for u- and v- 4-spinors have solutions with {p}0=+/- {E}p=+/- \\sqrt{{p}2+{m}2}. The same is true for higher-spin equations. Meanwhile, every book considers the equality p0 = Ep for both u- and v- spinors of the (1/2, 0) ⊕ (0, 1/2)) representation only, thus applying the Dirac-Feynman-Stueckelberg procedure for elimination of the negative-energy solutions. The recent Ziino works (and, independently, the articles of several others) show that the Fock space can be doubled. We re-consider this possibility on the quantum field level for both S = 1/2 and higher spin particles. The third example is: we postulate the non-commutativity of 4-momenta, and we derive the mass splitting in the Dirac equation. Some applications are discussed.

Interacting Electrons in Graphene: Fermi Velocity Renormalization and Optical Response

NASA Astrophysics Data System (ADS)

Stauber, T.; Parida, P.; Trushin, M.; Ulybyshev, M. V.; Boyda, D. L.; Schliemann, J.

2017-06-01

We have developed a Hartree-Fock theory for electrons on a honeycomb lattice aiming to solve a long-standing problem of the Fermi velocity renormalization in graphene. Our model employs no fitting parameters (like an unknown band cutoff) but relies on a topological invariant (crystal structure function) that makes the Hartree-Fock sublattice spinor independent of the electron-electron interaction. Agreement with the experimental data is obtained assuming static self-screening including local field effects. As an application of the model, we derive an explicit expression for the optical conductivity and discuss the renormalization of the Drude weight. The optical conductivity is also obtained via precise quantum Monte Carlo calculations which compares well to our mean-field approach.

Differential Geometry and Lie Groups for Physicists

NASA Astrophysics Data System (ADS)

Fecko, Marián.

2006-10-01

Introduction; 1. The concept of a manifold; 2. Vector and tensor fields; 3. Mappings of tensors induced by mappings of manifolds; 4. Lie derivative; 5. Exterior algebra; 6. Differential calculus of forms; 7. Integral calculus of forms; 8. Particular cases and applications of Stoke's Theorem; 9. Poincaré Lemma and cohomologies; 10. Lie Groups - basic facts; 11. Differential geometry of Lie Groups; 12. Representations of Lie Groups and Lie Algebras; 13. Actions of Lie Groups and Lie Algebras on manifolds; 14. Hamiltonian mechanics and symplectic manifolds; 15. Parallel transport and linear connection on M; 16. Field theory and the language of forms; 17. Differential geometry on TM and T*M; 18. Hamiltonian and Lagrangian equations; 19. Linear connection and the frame bundle; 20. Connection on a principal G-bundle; 21. Gauge theories and connections; 22. Spinor fields and Dirac operator; Appendices; Bibliography; Index.

Differential Geometry and Lie Groups for Physicists

NASA Astrophysics Data System (ADS)

Fecko, Marián.

2011-03-01

Introduction; 1. The concept of a manifold; 2. Vector and tensor fields; 3. Mappings of tensors induced by mappings of manifolds; 4. Lie derivative; 5. Exterior algebra; 6. Differential calculus of forms; 7. Integral calculus of forms; 8. Particular cases and applications of Stoke's Theorem; 9. Poincaré Lemma and cohomologies; 10. Lie Groups - basic facts; 11. Differential geometry of Lie Groups; 12. Representations of Lie Groups and Lie Algebras; 13. Actions of Lie Groups and Lie Algebras on manifolds; 14. Hamiltonian mechanics and symplectic manifolds; 15. Parallel transport and linear connection on M; 16. Field theory and the language of forms; 17. Differential geometry on TM and T*M; 18. Hamiltonian and Lagrangian equations; 19. Linear connection and the frame bundle; 20. Connection on a principal G-bundle; 21. Gauge theories and connections; 22. Spinor fields and Dirac operator; Appendices; Bibliography; Index.

Goedel, Penrose, anti-Mach: Extra supersymmetries of time-dependent plane waves

NASA Astrophysics Data System (ADS)

Blau, Matthias; Meessen, Patrick; O'Loughlin, Martin

2003-09-01

We prove that M-theory plane waves with extra supersymmetries are necessarily homogeneous (but possibly time-dependent), and we show by explicit construction that such time-dependent plane waves can admit extra supersymmetries. To that end we study the Penrose limits of Gödel-like metrics, show that the Penrose limit of the M-theory Gödel metric (with 20 supercharges) is generically a time-dependent homogeneous plane wave of the anti-Mach type, and display the four extra Killings spinors in that case. We conclude with some general remarks on the Killing spinor equations for homogeneous plane waves.

Some remarks on the attractor behaviour in ELKO cosmology

NASA Astrophysics Data System (ADS)

Pereira, S. H.; A. Pinho S., S.; Hoff da Silva, J. M.

2014-08-01

Recent results on the dynamical stability of a system involving the interaction of the ELKO spinor field with standard matter in the universe have been reanalysed, and the conclusion is that such system does not exhibit isolated stable points that could alleviate the cosmic coincidence problem. When a constant parameter δ related to the potential of the ELKO field is introduced in the system however, stable fixed points are found for some specific types of interaction between the ELKO field and matter. Although the parameter δ is related to an unknown potential, in order to satisfy the stability conditions and also that the fixed points are real, the range of the constant parameter δ can be constrained for the present time and the coincidence problem can be alleviated for some specific interactions. Such restriction on the ELKO potential opens possibility to apply the ELKO field as a candidate to dark energy in the universe, and so explain the present phase of acceleration of the universe through the decay of the ELKO field into matter.

Symmetries, supersymmetries and cohomologies in gauge theories

NASA Astrophysics Data System (ADS)

Bǎbǎlîc, Elena-Mirela

2009-12-01

The main subjects approached in the thesis are the following: a) the derivation of the interactions in two space-time dimensions in a particular class of topological BF models; b) the construction of the couplings in D ≥ 5 dimensions between one massless tensor field with the mixed symmetry (3, 1) and one with the mixed symmetry of the Riemann tensor; c) the evaluation of the existence of interactions in D ≥ 5 dimensions between two different collections of massless tensor fields with the mixed symmetries (3, 1) and (2, 2); d) the analysis of the relation between the BRST charges obtained in the pure-spinor formalism, respectively in the κ-symmetric one for the supermembrane in eleven dimensions. Our procedure for the first three subjects is based on solving the equations that describe the deformation of the solution to the master equation by means of specific cohomological techniques, while for the fourth one we will use techniques specific to the BRST Hamiltonian approach in order to write the BRST charge. The interactions are obtained under the following hypotheses: locality, Lorentz covariance, Poincare invariance, analyticity of the deformations, and preservation of the number of derivatives on each field. The first three assumptions imply that the interacting theory is local in space-time, Lorentz covariant and Poincare invariant. The analyticity of the deformations refers to the fact that the deformed solution to the master equation is analytical in the coupling constant and reduces to the original solution in the free limit. The conservation of the number of derivatives on each field with respect to the free theory means here that the following two requirements are simultaneously satisfied: (i) the derivative order of the equations of motion on each field is the same for the free and respectively for the interacting theory; (ii) the maximum number of derivatives in the interaction vertices is equal to two, i.e. the maximum number of derivatives from the free Lagrangian. The main results of the thesis are: interactions in two space-time dimensions for a particular class of BF models; interactions between one massless tensor field with the mixed symmetry (3, 1) and one with the mixed symmetry of the Riemann tensor; interactions between collections of massless tensor fields with the mixed symmetries (3, 1) and (2, 2); relating the kappa-symmetric and pure-spinor versions of the supermembrane in eleven dimensions.

Lagrangian formulation of the 2(2S+1)-component model and its connection with the skew symmetric/tensor description

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dvoeglazov, V.V.

1993-12-01

In the framework of the 2(2S + 1)-component theory for massless particles, the dynamical invariants have been derived from the Lagrangian density which is considered to be a 4-vector. A la Majorana interpretation of the 6-component spinors, the field operators of S=1 particles, as the left- and right-circularly polarized radiation, leads the author to the conserved quantities which are analogous to ones obtained by Lipkin and Sudbery. The scalar Lagrangian of this model is shown to be equivalent to the Lagrangian of a free massless field, introduced by Hayashi. As a consequence of a new {open_quotes}gauge{close_quotes} invariance this skew-symmetric fieldmore » describes physical particles with the longitudinal components only.« less

Dynamical Symmetry Breaking in Models of Spinor Fields with Quartic Interactions in (1+1) Dimensions

NASA Astrophysics Data System (ADS)

Wang, Rhung-tai; Ni, Guang-jiong

1982-07-01

A nonperturbative method, namely, variational method together with canonical transformations, is developed to study dynamical symmetry breaking. This method has been applied in the models of two dimensional massless fermion fields with quartic interactions. The results imply that the mechanism of dynamical symmetry breaking bears some analogy to the phenomenon of superconductivity. The new vacuum \\mid \\tilde{0}> is just a relativistic BCS groundstate, In this vacuum \\mid ^≈0>, we can observe a quasi-particle with mass "MF" Furthermore, correlative vacuum \\mid ^≈0> exists and the mesons emerge with masses "O" and "2MF". It is also shown that dynamical symmetry breaking always occurs in the models with infrared slavery and asymptotic freedom, while it is meaningless to discuss dynamical symmetry breaking in infrared stable theory.

Energy bounds in designer gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Amsel, Aaron J.; Marolf, Donald

We consider asymptotically anti-de Sitter gravity coupled to tachyonic scalar fields with mass at or slightly above the Breitenlohner-Freedman bound in d{>=}4 spacetime dimensions. The boundary conditions in these ''designer gravity'' theories are defined in terms of an arbitrary function W. We give a general argument that the Hamiltonian generators of asymptotic symmetries for such systems will be finite, and proceed to construct these generators using the covariant phase space method. The direct calculation confirms that the generators are finite and shows that they take the form of the pure gravity result plus additional contributions from the scalar fields. Bymore » comparing the generators to the spinor charge, we derive a lower bound on the gravitational energy when W has a global minimum and the Breitenlohner-Freedman bound is not saturated.« less

Cosmological rotating black holes in five-dimensional fake supergravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nozawa, Masato; Maeda, Kei-ichi; Waseda Research Institute for Science and Engineering, Okubo 3-4-1, Shinjuku, Tokyo 169-8555

2011-01-15

In recent series of papers, we found an arbitrary dimensional, time-evolving, and spatially inhomogeneous solution in Einstein-Maxwell-dilaton gravity with particular couplings. Similar to the supersymmetric case, the solution can be arbitrarily superposed in spite of nontrivial time-dependence, since the metric is specified by a set of harmonic functions. When each harmonic has a single point source at the center, the solution describes a spherically symmetric black hole with regular Killing horizons and the spacetime approaches asymptotically to the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmology. We discuss in this paper that in 5 dimensions, this equilibrium condition traces back to the first-order 'Killing spinor'more » equation in 'fake supergravity' coupled to arbitrary U(1) gauge fields and scalars. We present a five-dimensional, asymptotically FLRW, rotating black-hole solution admitting a nontrivial 'Killing spinor', which is a spinning generalization of our previous solution. We argue that the solution admits nondegenerate and rotating Killing horizons in contrast with the supersymmetric solutions. It is shown that the present pseudo-supersymmetric solution admits closed timelike curves around the central singularities. When only one harmonic is time-dependent, the solution oxidizes to 11 dimensions and realizes the dynamically intersecting M2/M2/M2-branes in a rotating Kasner universe. The Kaluza-Klein-type black holes are also discussed.« less

Quantum Quenches in a Spinor Condensate

NASA Astrophysics Data System (ADS)

Lamacraft, Austen

2007-04-01

We discuss the ordering of a spin-1 condensate when quenched from its paramagnetic phase to its ferromagnetic phase by reducing the magnetic field. We first elucidate the nature of the equilibrium quantum phase transition. Quenching rapidly through this transition reveals XY ordering either at a specific wave vector, or the “light-cone” correlations familiar from relativistic theories, depending on the end point of the quench. For a quench proceeding at a finite rate the ordering scale is governed by the Kibble-Zurek mechanism. The creation of vortices through growth of the magnetization fluctuations is also discussed. The long-time dynamics again depends on the end point, conserving the order parameter in a zero field, but not at a finite field, with differing exponents for the coarsening of magnetic order. The results are discussed in the light of a recent experiment by Sadler et al.

Compactification and inflation in the superstring theory from the condensation of gravitino pairs

NASA Astrophysics Data System (ADS)

Pollock, M. D.

1987-12-01

We discuss the possibility that inflation can occur in the E8×E8' heterotic superstring theory, if there is a pair condensation of the gravitino field ψA and also of the Majorana-Weyl spinor λ, as suggested by the Helayël-Neto and Smith. In the absence of a condensation of the anti-symmetric tensor field HMNP, then the associated potential V(θ,φ) is bounded from below and independent of the dilaton field φ. It can be made to vanish at the minimum, where the compactification scale θ is fixed. Alternatively, a small cosmological constant may remain (ultimately to be cancelled by radiative corrections at the lower energy scale of the gaugino condensation), which could in principle lead to inflation. Present address: Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Bombay 400 005, India.

Nonsingular, big-bounce cosmology from spinor-torsion coupling

NASA Astrophysics Data System (ADS)

Popławski, Nikodem

2012-05-01

The Einstein-Cartan-Sciama-Kibble theory of gravity removes the constraint of general relativity that the affine connection be symmetric by regarding its antisymmetric part, the torsion tensor, as a dynamical variable. The minimal coupling between the torsion tensor and Dirac spinors generates a spin-spin interaction which is significant in fermionic matter at extremely high densities. We show that such an interaction averts the unphysical big-bang singularity, replacing it with a cusp-like bounce at a finite minimum scale factor, before which the Universe was contracting. This scenario also explains why the present Universe at largest scales appears spatially flat, homogeneous and isotropic.

Baker-Akhiezer Spinor Kernel and Tau-functions on Moduli Spaces of Meromorphic Differentials

NASA Astrophysics Data System (ADS)

Kalla, C.; Korotkin, D.

2014-11-01

In this paper we study the Baker-Akhiezer spinor kernel on moduli spaces of meromorphic differentials on Riemann surfaces. We introduce the Baker-Akhiezer tau-function which is related to both the Bergman tau-function (which was studied before in the context of Hurwitz spaces and spaces of holomorphic Abelian and quadratic differentials) and the KP tau-function on such spaces. In particular, we derive variational formulas of Rauch-Ahlfors type on moduli spaces of meromorphic differentials with prescribed singularities: we use the system of homological coordinates, consisting of absolute and relative periods of the meromorphic differential, and show how to vary the fundamental objects associated to a Riemann surface (the matrix of b-periods, normalized Abelian differentials, the Bergman bidifferential, the Szegö kernel and the Baker-Akhiezer spinor kernel) with respect to these coordinates. The variational formulas encode dependence both on the moduli of the Riemann surface and on the choice of meromorphic differential (variation of the meromorphic differential while keeping the Riemann surface fixed corresponds to flows of KP type). Analyzing the global properties of the Bergman and Baker-Akhiezer tau-functions, we establish relationships between various divisor classes on the moduli spaces.

On twisting type [N] ⊗ [N] Ricci flat complex spacetimes with two homothetic symmetries

NASA Astrophysics Data System (ADS)

Chudecki, Adam; Przanowski, Maciej

2018-04-01

In this article, H H spaces of type [N] ⊗ [N] with twisting congruence of null geodesics defined by the 4-fold undotted and dotted Penrose spinors are investigated. It is assumed that these spaces admit two homothetic symmetries. The general form of the homothetic vector fields is found. New coordinates are introduced, which enable us to reduce the H H system of partial differential equations to one ordinary differential equation (ODE) on one holomorphic function. In a special case, this is a second-order ODE and its general solution is explicitly given. In the generic case, one gets rather involved fifth-order ODE.

Non-perturbative calculation of orbital and spin effects in molecules subject to non-uniform magnetic fields

NASA Astrophysics Data System (ADS)

Sen, Sangita; Tellgren, Erik I.

2018-05-01

External non-uniform magnetic fields acting on molecules induce non-collinear spin densities and spin-symmetry breaking. This necessitates a general two-component Pauli spinor representation. In this paper, we report the implementation of a general Hartree-Fock method, without any spin constraints, for non-perturbative calculations with finite non-uniform fields. London atomic orbitals are used to ensure faster basis convergence as well as invariance under constant gauge shifts of the magnetic vector potential. The implementation has been applied to investigate the joint orbital and spin response to a field gradient—quantified through the anapole moments—of a set of small molecules. The relative contributions of orbital and spin-Zeeman interaction terms have been studied both theoretically and computationally. Spin effects are stronger and show a general paramagnetic behavior for closed shell molecules while orbital effects can have either direction. Basis set convergence and size effects of anapole susceptibility tensors have been reported. The relation of the mixed anapole susceptibility tensor to chirality is also demonstrated.

Unimodular Einstein-Cartan gravity: Dynamics and conservation laws

NASA Astrophysics Data System (ADS)

Bonder, Yuri; Corral, Cristóbal

2018-04-01

Unimodular gravity is an interesting approach to address the cosmological constant problem, since the vacuum energy density of quantum fields does not gravitate in this framework, and the cosmological constant appears as an integration constant. These features arise as a consequence of considering a constrained volume element 4-form that breaks the diffeomorphisms invariance down to volume preserving diffeomorphisms. In this work, the first-order formulation of unimodular gravity is presented by considering the spin density of matter fields as a source of spacetime torsion. Even though the most general matter Lagrangian allowed by the symmetries is considered, dynamical restrictions arise on their functional dependence. The field equations are obtained and the conservation laws associated with the symmetries are derived. It is found that, analogous to torsion-free unimodular gravity, the field equation for the vierbein is traceless; nevertheless, torsion is algebraically related to the spin density as in standard Einstein-Cartan theory. The particular example of massless Dirac spinors is studied, and comparisons with standard Einstein-Cartan theory are shown.

Spin-Orbit-Coupled Interferometry with Ring-Trapped Bose-Einstein Condensates

NASA Astrophysics Data System (ADS)

Helm, J. L.; Billam, T. P.; Rakonjac, A.; Cornish, S. L.; Gardiner, S. A.

2018-02-01

We propose a method of atom interferometry using a spinor Bose-Einstein condensate with a time-varying magnetic field acting as a coherent beam splitter. Our protocol creates long-lived superpositional counterflow states, which are of fundamental interest and can be made sensitive to both the Sagnac effect and magnetic fields on the sub-μ G scale. We split a ring-trapped condensate, initially in the mf=0 hyperfine state, into superpositions of internal mf=±1 states and condensate superflow, which are spin-orbit coupled. After interrogation, the relative phase accumulation can be inferred from a population transfer to the mf=±1 states. The counterflow generation protocol is adiabatically deterministic and does not rely on coupling to additional optical fields or mechanical stirring techniques. Our protocol can maximize the classical Fisher information for any rotation, magnetic field, or interrogation time and so has the maximum sensitivity available to uncorrelated particles. Precision can increase with the interrogation time and so is limited only by the lifetime of the condensate.

Radio-Frequency-Controlled Cold Collisions and Universal Properties of Unitary Bose Gases

NASA Astrophysics Data System (ADS)

Ding, Yijue

This thesis investigates two topics: ultracold atomic collisions in a radio-frequency field and universal properties of a degenerate unitary Bose gas. One interesting point of the unitary Bose gas is that the system has only one length scale, that is, the average interparticle distance. This single parameter determines all properties of the gas, which is called the universality of the system. We first introduce a renormalized contact interaction to extend the validity of the zero-range interaction to large scattering lengths. Then this renormalized interaction is applied to many-body theories to determined those universal relations of the system. From the few-body perspective, we discuss the scattering between atoms in a single-color radio-frequency field. Our motivation is proposing the radio-frequency field as an effective tool to control interactions between cold atoms. Such a technique may be useful in future experiments such as creating phase transitions in spinor condensates. We also discuss the formation of ultracold molecules using radio-freqency fields from a time-dependent approach.

Classical Field Theory and the Stress-Energy Tensor

NASA Astrophysics Data System (ADS)

Swanson, Mark S.

2015-09-01

This book is a concise introduction to the key concepts of classical field theory for beginning graduate students and advanced undergraduate students who wish to study the unifying structures and physical insights provided by classical field theory without dealing with the additional complication of quantization. In that regard, there are many important aspects of field theory that can be understood without quantizing the fields. These include the action formulation, Galilean and relativistic invariance, traveling and standing waves, spin angular momentum, gauge invariance, subsidiary conditions, fluctuations, spinor and vector fields, conservation laws and symmetries, and the Higgs mechanism, all of which are often treated briefly in a course on quantum field theory. The variational form of classical mechanics and continuum field theory are both developed in the time-honored graduate level text by Goldstein et al (2001). An introduction to classical field theory from a somewhat different perspective is available in Soper (2008). Basic classical field theory is often treated in books on quantum field theory. Two excellent texts where this is done are Greiner and Reinhardt (1996) and Peskin and Schroeder (1995). Green's function techniques are presented in Arfken et al (2013).

Spin flux and magnetic solitons in an interacting two-dimensional electron gas: Topology of two-valued wave functions

NASA Astrophysics Data System (ADS)

John, Sajeev; Golubentsev, Andrey

1995-01-01

It is suggested that an interacting many-electron system in a two-dimensional lattice may condense into a topological magnetic state distinct from any discussed previously. This condensate exhibits local spin-1/2 magnetic moments on the lattice sites but is composed of a Slater determinant of single-electron wave functions which exist in an orthogonal sector of the electronic Hilbert space from the sector describing traditional spin-density-wave or spiral magnetic states. These one-electron spinor wave functions have the distinguishing property that they are antiperiodic along a closed path encircling any elementary plaquette of the lattice. This corresponds to a 2π rotation of the internal coordinate frame of the electron as it encircles the plaquette. The possibility of spinor wave functions with spatial antiperiodicity is a direct consequence of the two-valuedness of the internal electronic wave function defined on the space of Euler angles describing its spin. This internal space is the topologically, doubly-connected, group manifold of SO(3). Formally, these antiperiodic wave functions may be described by passing a flux which couples to spin (rather than charge) through each of the elementary plaquettes of the lattice. When applied to the two-dimensional Hubbard model with one electron per site, this new topological magnetic state exhibits a relativistic spectrum for charged, quasiparticle excitations with a suppressed one-electron density of states at the Fermi level. For a topological antiferromagnet on a square lattice, with the standard Hartree-Fock, spin-density-wave decoupling of the on-site Hubbard interaction, there is an exact mapping of the low-energy one-electron excitation spectrum to a relativistic Dirac continuum field theory. In this field theory, the Dirac mass gap is precisely the Mott-Hubbard charge gap and the continuum field variable is an eight-component Dirac spinor describing the components of physical electron-spin amplitude on each of the four sites of the elementary plaquette in the original Hubbard model. Within this continuum model we derive explicitly the existence of hedgehog Skyrmion textures as local minima of the classical magnetic energy. These magnetic solitons carry a topological winding number μ associated with the vortex rotation of the background magnetic moment field by a phase angle 2πμ along a path encircling the soliton. Such solitons also carry a spin flux of μπ through the plaquette on which they are centered. The μ=1 hedgehog Skyrmion describes a local transition from the topological (antiperiodic) sector of the one-electron Hilbert space to the nontopological sector. We derive from first principles the existence of deep level localized electronic states within the Mott-Hubbard charge gap for the μ=1 and 2 solitons. The spectrum of localized states is symmetric about E=0 and each subgap electronic level can be occupied by a pair of electrons in which one electron resides primarily on one sublattice and the second electron on the other sublattice. It is suggested that flux-carrying solitons and the subgap electronic structure which they induce are important in understanding the physical behavior of doped Mott insulators.

A spatially homogeneous and isotropic Einstein-Dirac cosmology

NASA Astrophysics Data System (ADS)

Finster, Felix; Hainzl, Christian

2011-04-01

We consider a spatially homogeneous and isotropic cosmological model where Dirac spinors are coupled to classical gravity. For the Dirac spinors we choose a Hartree-Fock ansatz where all one-particle wave functions are coherent and have the same momentum. If the scale function is large, the universe behaves like the classical Friedmann dust solution. If however the scale function is small, quantum effects lead to oscillations of the energy-momentum tensor. It is shown numerically and proven analytically that these quantum oscillations can prevent the formation of a big bang or big crunch singularity. The energy conditions are analyzed. We prove the existence of time-periodic solutions which go through an infinite number of expansion and contraction cycles.

Discrete symmetries and the propagator approach to coupled fermions in Quantum Field Theory. Generalities: The case of a single fermion-antifermion pair

NASA Astrophysics Data System (ADS)

Duret, Q.; Machet, B.

2010-10-01

Starting from Wigner's symmetry representation theorem, we give a general account of discrete symmetries (parity P, charge conjugation C, time-reversal T), focusing on fermions in Quantum Field Theory. We provide the rules of transformation of Weyl spinors, both at the classical level (grassmanian wave functions) and quantum level (operators). Making use of Wightman's definition of invariance, we outline ambiguities linked to the notion of classical fermionic Lagrangian. We then present the general constraints cast by these transformations and their products on the propagator of the simplest among coupled fermionic system, the one made with one fermion and its antifermion. Last, we put in correspondence the propagation of C eigenstates (Majorana fermions) and the criteria cast on their propagator by C and CP invariance.

Angular Momentum of a Bose-Einstein Condensate in a Synthetic Rotational Field

NASA Astrophysics Data System (ADS)

Qu, Chunlei; Stringari, Sandro

2018-05-01

By applying a position-dependent detuning to a spin-orbit-coupled Hamiltonian with equal Rashba and Dresselhaus coupling, we exploit the behavior of the angular momentum of a harmonically trapped Bose-Einstein condensed atomic gas and discuss the distinctive role of its canonical and spin components. By developing the formalism of spinor hydrodynamics, we predict the precession of the dipole oscillation caused by the synthetic rotational field, in analogy with the precession of the Foucault pendulum, the excitation of the scissors mode, following the sudden switching off of the detuning, and the occurrence of Hall-like effects. When the detuning exceeds a critical value, we observe a transition from a vortex free, rigidly rotating quantum gas to a gas containing vortices with negative circulation which results in a significant reduction of the total angular momentum.

Functional Wigner representation of quantum dynamics of Bose-Einstein condensate

NASA Astrophysics Data System (ADS)

Opanchuk, B.; Drummond, P. D.

2013-04-01

We develop a method of simulating the full quantum field dynamics of multi-mode multi-component Bose-Einstein condensates in a trap. We use the truncated Wigner representation to obtain a probabilistic theory that can be sampled. This method produces c-number stochastic equations which may be solved using conventional stochastic methods. The technique is valid for large mode occupation numbers. We give a detailed derivation of methods of functional Wigner representation appropriate for quantum fields. Our approach describes spatial evolution of spinor components and properly accounts for nonlinear losses. Such techniques are applicable to calculating the leading quantum corrections, including effects such as quantum squeezing, entanglement, EPR correlations, and interactions with engineered nonlinear reservoirs. By using a consistent expansion in the inverse density, we are able to explain an inconsistency in the nonlinear loss equations found by earlier authors.

Extended spin symmetry and the standard model

NASA Astrophysics Data System (ADS)

Besprosvany, J.; Romero, R.

2010-12-01

We review unification ideas and explain the spin-extended model in this context. Its consideration is also motivated by the standard-model puzzles. With the aim of constructing a common description of discrete degrees of freedom, as spin and gauge quantum numbers, the model departs from q-bits and generalized Hilbert spaces. Physical requirements reduce the space to one that is represented by matrices. The classification of the representations is performed through Clifford algebras, with its generators associated with Lorentz and scalar symmetries. We study a reduced space with up to two spinor elements within a matrix direct product. At given dimension, the demand that Lorentz symmetry be maintained, determines the scalar symmetries, which connect to vector-and-chiral gauge-interacting fields; we review the standard-model information in each dimension. We obtain fermions and bosons, with matter fields in the fundamental representation, radiation fields in the adjoint, and scalar particles with the Higgs quantum numbers. We relate the fields' representation in such spaces to the quantum-field-theory one, and the Lagrangian. The model provides a coupling-constant definition.

Pure spinors, function superspaces and supergravity theories in ten and eleven dimensions

NASA Astrophysics Data System (ADS)

Howe, P. S.

1991-12-01

The constraints of d = 10 supergravity coupled to super Yang-Mills and d = 11 supergravity are studied from the viewpoint of the differential geometry of certain function superspaces. For d = 10 the appropriate function space is loop superspace, and the presence of Chern-Simons terms in the coupling of supergravity to Yang-Mills is incorporated into the formalism via a central extension of the loop group of the Yang-Mills group. For d = 11 the function superspace is the space of maps from a compact two-manifold to superspace. In both cases the superspaces include additional commuting coordinates which are pure spinors. Permanent address: Department of Mathematics, King's College, London WC2R 2LS, UK.

Non-Existence of Black Hole Solutionsfor a Spherically Symmetric, Static Einstein-Dirac-Maxwell System

NASA Astrophysics Data System (ADS)

Finster, Felix; Smoller, Joel; Yau, Shing-Tung

We consider for j=1/2, 3/2,... a spherically symmetric, static system of (2j+1) Dirac particles, each having total angular momentum j. The Dirac particles interact via a classical gravitational and electromagnetic field. The Einstein-Dirac-Maxwell equations for this system are derived. It is shown that, under weak regularity conditions on the form of the horizon, the only black hole solutions of the EDM equations are the Reissner-Nordstrom solutions. In other words, the spinors must vanish identically. Applied to the gravitational collapse of a "cloud" of spin-1/2-particles to a black hole, our result indicates that the Dirac particles must eventually disappear inside the event horizon.

From inflation to recent cosmic acceleration: the fermionic Elko field driving the evolution of the universe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pereira, S.H.; Guimarães, T.M., E-mail: shpereira@feg.unesp.br, E-mail: thiago.mogui@gmail.com

In this paper we construct the complete evolution of the universe driven by the mass dimension one dark spinor called Elko, starting with inflation, passing by the matter dominated era and finishing with the recent accelerated expansion. The dynamic of the fermionic Elko field with a symmetry breaking type potential can reproduce all phases of the universe in a natural and elegant way. The dynamical equations in general case and slow roll conditions in the limit H || m {sub pl} are also presented for the Elko system. Numerical analysis for the number of e-foldings during inflation, energy density aftermore » inflation and for present time and also the actual size of the universe are in good agreement with the standard model of cosmology. An interpretation of the inflationary phase as a result of Pauli exclusion principle is also possible if the Elko field is treated as an average value of its quantum analogue.« less

Topologically massive magnetic monopoles

NASA Astrophysics Data System (ADS)

Aliev, A. N.; Nutku, Y.; Saygili, K.

2000-10-01

We show that in the Maxwell-Chern-Simons theory of topologically massive electrodynamics the Dirac string of a monopole becomes a cone in anti-de Sitter space with the opening angle of the cone determined by the topological mass, which in turn is related to the square root of the cosmological constant. This proves to be an example of a physical system, a priori completely unrelated to gravity, which nevertheless requires curved spacetime for its very existence. We extend this result to topologically massive gravity coupled to topologically massive electrodynamics within the framework of the theory of Deser, Jackiw and Templeton. The two-component spinor formalism, which is a Newman-Penrose type approach for three dimensions, is extended to include both the electrodynamical and gravitational topologically massive field equations. Using this formalism exact solutions of the coupled Deser-Jackiw-Templeton and Maxwell-Chern-Simons field equations for a topologically massive monopole are presented. These are homogeneous spaces with conical deficit. Pure Einstein gravity coupled to the Maxwell-Chern-Simons field does not admit such a monopole solution.

Holographic Tools for Probing the Dynamics of Strongly Coupled Field Theories

NASA Astrophysics Data System (ADS)

Fuini, John F.

Since it was conjectured almost 20 years ago, AdS/CFT duality, or holography, has enabled steady progress in understanding certain gauge theories in the strongly coupled limit. In this thesis we examine various aspects of holography and holographic techniques, as well as particular applications to the dynamics of strongly coupled plasmas. We discuss the energy loss of general probe defects in generic holographic plasmas and the lifetime of quasinormal modes of sufficiently short-wavelength in a strongly coupled N = 4 Super Yang-Mills (SYM) plasma. We then perform a thorough investigation of the far-from-equilibrium dynamics of the SYM plasma, focusing on how the presence of large magnetic fields or chemical potentials affect the timescale of equilibration. Finally we discuss some non-relativistic directions by finding a covariant construction of Lagrangians for spinor fields in generic Newton-Cartan backgrounds via a non-relativistic reduction, which may assist in the construction of non-relativistic versions of holography.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Birmingham, D.; Kantowski, R.; Milton, K.A.

We use two methods of computing the unique logarithmically divergent part of the Casimir energy for massive scalar and spinor fields defined on even-dimensional Kaluza-Klein spaces of the form M/sup 4/ x S/sup N//sup 1/ x S/sup N//sup 2/ x xxx. Both methods (heat kernel and direct) give identical results. The first evaluates the required internal zeta function by identifying it in the asymptotic expansion of the trace of the heat kernel, and the second evaluates the zeta function directly using the Euler-Maclaurin sum formula. In Appendix C we tabulate these energies for all spaces of total internal dimension lessmore » than or equal to6. These methods are easily applied to vector and tensor fields needed in computing one-loop vacuum gravitational energies on these spaces. Stable solutions are given for internal structure S/sup 2/ x S/sup 2/.« less

Functional Wigner representation of quantum dynamics of Bose-Einstein condensate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Opanchuk, B.; Drummond, P. D.

2013-04-15

We develop a method of simulating the full quantum field dynamics of multi-mode multi-component Bose-Einstein condensates in a trap. We use the truncated Wigner representation to obtain a probabilistic theory that can be sampled. This method produces c-number stochastic equations which may be solved using conventional stochastic methods. The technique is valid for large mode occupation numbers. We give a detailed derivation of methods of functional Wigner representation appropriate for quantum fields. Our approach describes spatial evolution of spinor components and properly accounts for nonlinear losses. Such techniques are applicable to calculating the leading quantum corrections, including effects such asmore » quantum squeezing, entanglement, EPR correlations, and interactions with engineered nonlinear reservoirs. By using a consistent expansion in the inverse density, we are able to explain an inconsistency in the nonlinear loss equations found by earlier authors.« less

All-Optical Stern-Gerlach Effect

NASA Astrophysics Data System (ADS)

Karnieli, Aviv; Arie, Ady

2018-01-01

We introduce a novel formalism in which the paraxial coupled wave equations of the nonlinear optical sum-frequency generation process are shown to be equivalent to the Pauli equation describing the dynamics of a spin-1 /2 particle in a spatially varying magnetic field. This interpretation gives rise to a new classical state of paraxial light, described by a mutual beam comprising of two frequencies. As a straightforward application, we propose the existence of an all-optical Stern-Gerlach effect, where an idler beam is deflected by a gradient in the nonlinear coupling, into two mutual beams of the idler and signal waves (equivalent to oppositely oriented spinors), propagating in two discrete directions. The Stern-Gerlach deflection angle and the intensity pattern in the far field are then obtained analytically, in terms of the parameters of the original optical system, laying the grounds for future experimental realizations.

Route to non-Abelian quantum turbulence in spinor Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Mawson, Thomas; Ruben, Gary; Simula, Tapio

2015-06-01

We have studied computationally the collision dynamics of spin-2 Bose-Einstein condensates initially confined in a triple-well trap. Depending on the phase structure of the initial-state spinor wave function, the collision of the three condensate fragments produces one of many possible vortex-antivortex lattices, after which the system transitions to quantum turbulence. We find that the emerging vortex lattice structures can be described in terms of multiwave interference. We show that the three-fragment collisions can be used to systematically produce staggered vortex-antivortex honeycomb lattices of fractional-charge vortices, whose collision dynamics are known to be non-Abelian. Such condensate collider experiments could potentially be used as a controllable pathway to generating non-Abelian superfluid turbulence with networks of vortex rungs.

Werner states and the two-spinors Heisenberg anti-ferromagnet

NASA Astrophysics Data System (ADS)

Batle, J.; Casas, M.; Plastino, A.; Plastino, A. R.

2005-08-01

We ascertain, following ideas of Arnesen, Bose, and Vedral concerning thermal entanglement [Phys. Rev. Lett. 87 (2001) 017901] and using the statistical tool called entropic non-triviality [P.W. Lamberti, M.T. Martin, A. Plastino, O.A. Rosso, Physica A 334 (2004) 119], that there is a one-to-one correspondence between (i) the mixing coefficient x of a Werner state, on the one hand, and (ii) the temperature T of the one-dimensional Heisenberg two-spin chain with a magnetic field B along the z-axis, on the other one. This is true for each value of B below a certain critical value B. The pertinent mapping depends on the particular B-value one selects within such a range.

Valley-isospin dependence of the quantum Hall effect in a graphene p-n junction

NASA Astrophysics Data System (ADS)

Tworzydło, J.; Snyman, I.; Akhmerov, A. R.; Beenakker, C. W. J.

2007-07-01

We calculate the conductance G of a bipolar junction in a graphene nanoribbon, in the high-magnetic-field regime where the Hall conductance in the p -doped and n -doped regions is 2e2/h . In the absence of intervalley scattering, the result G=(e2/h)(1-cosΦ) depends only on the angle Φ between the valley isospins ( =Bloch vectors representing the spinor of the valley polarization) at the two opposite edges. This plateau in the conductance versus Fermi energy is insensitive to electrostatic disorder, while it is destabilized by the dispersionless edge state which may exist at a zigzag boundary. A strain-induced vector potential shifts the conductance plateau up or down by rotating the valley isospin.

Stepwise Bose-Einstein Condensation in a Spinor Gas.

PubMed

Frapolli, C; Zibold, T; Invernizzi, A; Jiménez-García, K; Dalibard, J; Gerbier, F

2017-08-04

We observe multistep condensation of sodium atoms with spin F=1, where the different Zeeman components m_{F}=0,±1 condense sequentially as the temperature decreases. The precise sequence changes drastically depending on the magnetization m_{z} and on the quadratic Zeeman energy q (QZE) in an applied magnetic field. For large QZE, the overall structure of the phase diagram is the same as for an ideal spin-1 gas, although the precise locations of the phase boundaries are significantly shifted by interactions. For small QZE, antiferromagnetic interactions qualitatively change the phase diagram with respect to the ideal case, leading, for instance, to condensation in m_{F}=±1, a phenomenon that cannot occur for an ideal gas with q>0.

Experimental demonstration of spinor slow light

NASA Astrophysics Data System (ADS)

Lee, Meng-Jung; Ruseckas, Julius; Lee, Chin-Yuan; Kudriašov, Viačeslav; Chang, Kao-Fang; Cho, Hung-Wen; JuzeliÅ«nas, Gediminas; Yu, Ite A.

2016-03-01

Over the last decade there has been a continuing interest in slow and stored light based on the electromagnetically induced transparency (EIT) effect, because of their potential applications in quantum information manipulation. However, previous experimental works all dealt with the single-component slow light which cannot be employed as a qubit. In this work, we report the first experimental demonstration of two-component or spinor slow light (SSL) using a double tripod (DT) atom-light coupling scheme. The oscillations between the two components, similar to the Rabi oscillation of a two-level system or a qubit, were observed. Single-photon SSL can be considered as two-color qubits. We experimentally demonstrated a possible application of the DT scheme as quantum memory and quantum rotator for the two-color qubits. This work opens up a new direction in the slow light research.

Spinor Structure and Internal Symmetries

NASA Astrophysics Data System (ADS)

Varlamov, V. V.

2015-10-01

Spinor structure and internal symmetries are considered within one theoretical framework based on the generalized spin and abstract Hilbert space. Complex momentum is understood as a generating kernel of the underlying spinor structure. It is shown that tensor products of biquaternion algebras are associated with the each irreducible representation of the Lorentz group. Space-time discrete symmetries P, T and their combination PT are generated by the fundamental automorphisms of this algebraic background (Clifford algebras). Charge conjugation C is presented by a pseudoautomorphism of the complex Clifford algebra. This description of the operation C allows one to distinguish charged and neutral particles including particle-antiparticle interchange and truly neutral particles. Spin and charge multiplets, based on the interlocking representations of the Lorentz group, are introduced. A central point of the work is a correspondence between Wigner definition of elementary particle as an irreducible representation of the Poincaré group and SU(3)-description (quark scheme) of the particle as a vector of the supermultiplet (irreducible representation of SU(3)). This correspondence is realized on the ground of a spin-charge Hilbert space. Basic hadron supermultiplets of SU(3)-theory (baryon octet and two meson octets) are studied in this framework. It is shown that quark phenomenologies are naturally incorporated into presented scheme. The relationship between mass and spin is established. The introduced spin-mass formula and its combination with Gell-Mann-Okubo mass formula allows one to take a new look at the problem of mass spectrum of elementary particles.

Torsion in gauge theory

NASA Astrophysics Data System (ADS)

Nieh, H. T.

2018-02-01

The potential conflict between torsion and gauge symmetry in the Riemann-Cartan curved spacetime was noted by Kibble in his 1961 pioneering paper and has since been discussed by many authors. Kibble suggested that, to preserve gauge symmetry, one should forgo the covariant derivative in favor of the ordinary derivative in the definition of the field strength Fμ ν for massless gauge theories, while for massive vector fields, covariant derivatives should be adopted. This view was further emphasized by Hehl et al. in their influential 1976 review paper. We address the question of whether this deviation from normal procedure by forgoing covariant derivatives in curved spacetime with torsion could give rise to inconsistencies in the theory, such as the quantum renormalizability of a realistic interacting theory. We demonstrate in this paper the one-loop renormalizability of a realistic gauge theory of gauge bosons interacting with Dirac spinors, such as the SU(3) chromodynamics, for the case of a curved Riemann-Cartan spacetime with totally antisymmetric torsion. This affirmative confirmation is one step toward providing justification for the assertion that the flat-space definition of the gauge-field strength should be adopted as the proper definition.

N = 1 supercurrents of eleven-dimensional supergravity

NASA Astrophysics Data System (ADS)

Becker, Katrin; Becker, Melanie; Butter, Daniel; Linch, William D.

2018-05-01

Eleven-dimensional supergravity can be formulated in superspaces locally of the form X × Y where X is 4D N = 1 conformal superspace and Y is an arbitrary 7-manifold admitting a G 2-structure. The eleven-dimensional 3-form and the stable 3-form on Y define the lowest component of a gauge superfield on X × Y that is chiral as a superfield on X. This chiral field is part of a tensor hierarchy giving rise to a superspace Chern-Simons action and its real field strength defines a lifting of the Hitchin functional on Y to the G 2 superspace X × Y . These terms are those of lowest order in a superspace Noether expansion in seven N = 1 conformal gravitino superfields Ψ. In this paper, we compute the O(Ψ) action to all orders in the remaining fields. The eleven-dimensional origin of the resulting non-linear structures is parameterized by the choice of a complex spinor on Y encoding the off-shell 4D N = 1 subalgebra of the eleven-dimensional super-Poincaré algebra.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fernando, Sudarshan; Gunaydin, Murat

Here, we extend our earlier work on the minimal unitary representation of SO(d, 2)and its deformations for d=4, 5and 6to arbitrary dimensions d. We show that there is a one-to-one correspondence between the minrep of SO(d, 2)and its deformations and massless conformal fields in Minkowskian spacetimes in ddimensions. The minrep describes a massless conformal scalar field, and its deformations describe massless conformal fields of higher spin. The generators of Joseph ideal vanish identically as operators for the quasiconformal realization of the minrep, and its enveloping algebra yields directly the standard bosonic AdS (d+1)/CFT d higher spin algebra. For deformed minrepsmore » the generators of certain deformations of Joseph ideal vanish as operators and their enveloping algebras lead to deformations of the standard bosonic higher spin algebra. In odd dimensions there is a unique deformation of the higher spin algebra corresponding to the spinor singleton. In even dimensions one finds infinitely many deformations of the higher spin algebra labelled by the eigenvalues of Casimir operator of the little group SO(d–2)for massless representations.« less

Very special relativity as relativity of dark matter: the Elko connection

NASA Astrophysics Data System (ADS)

Ahluwalia, D. V.; Horvath, S. P.

2010-11-01

In the very special relativity (VSR) proposal by Cohen and Glashow, it was pointed out that invariance under HOM (2) is both necessary and sufficient to explain the null result of the Michelson-Morely experiment. It is the quantum field theoretic demand of locality, or the requirement of P, T, CP, or CT invariance, that makes invariance under the Lorentz group a necessity. Originally it was conjectured that VSR operates at the Planck scale; we propose that the natural arena for VSR is at energies similar to the standard model, but in the dark sector. To this end we provide an ab initio spinor representation invariant under the SIM (2) avatar of VSR and construct a mass dimension one fermionic quantum field of spin one half. This field turns out to be a very close sibling of Elko and it exhibits the same striking property of intrinsic darkness with respect to the standard model fields. In the new construct, the tension between Elko and Lorentz symmetries is fully resolved. We thus entertain the possibility that the symmetries underlying the standard model matter and gauge fields are those of Lorentz, while the event space underlying the dark matter and the dark gauge fields supports the algebraic structure underlying VSR.

Hyperunified field theory and gravitational gauge-geometry duality

NASA Astrophysics Data System (ADS)

Wu, Yue-Liang

2018-01-01

A hyperunified field theory is built in detail based on the postulates of gauge invariance and coordinate independence along with the conformal scaling symmetry. All elementary particles are merged into a single hyper-spinor field and all basic forces are unified into a fundamental interaction governed by the hyper-spin gauge symmetry SP(1, D_h-1). The dimension D_h of hyper-spacetime is conjectured to have a physical origin in correlation with the hyper-spin charge of elementary particles. The hyper-gravifield fiber bundle structure of biframe hyper-spacetime appears naturally with the globally flat Minkowski hyper-spacetime as a base spacetime and the locally flat hyper-gravifield spacetime as a fiber that is viewed as a dynamically emerged hyper-spacetime characterized by a non-commutative geometry. The gravitational origin of gauge symmetry is revealed with the hyper-gravifield that plays an essential role as a Goldstone-like field. The gauge-gravity and gravity-geometry correspondences bring about the gravitational gauge-geometry duality. The basic properties of hyperunified field theory and the issue on the fundamental scale are analyzed within the framework of quantum field theory, which allows us to describe the laws of nature in deriving the gauge gravitational equation with the conserved current and the geometric gravitational equations of Einstein-like type and beyond.

Quasi-local gravitational angular momentum and centre of mass from generalised Witten equations

NASA Astrophysics Data System (ADS)

Wieland, Wolfgang

2017-03-01

Witten's proof for the positivity of the ADM mass gives a definition of energy in terms of three-surface spinors. In this paper, we give a generalisation for the remaining six Poincaré charges at spacelike infinity, which are the angular momentum and centre of mass. The construction improves on certain three-surface spinor equations introduced by Shaw. We solve these equations asymptotically obtaining the ten Poincaré charges as integrals over the Nester-Witten two-form. We point out that the defining differential equations can be extended to three-surfaces of arbitrary signature and we study them on the entire boundary of a compact four-dimensional region of spacetime. The resulting quasi-local expressions for energy and angular momentum are integrals over a two-dimensional cross-section of the boundary. For any two consecutive such cross-sections, conservation laws are derived that determine the influx (outflow) of matter and gravitational radiation.

Singular Atom Optics with Spinor BECs

NASA Astrophysics Data System (ADS)

Schultz, Justin T.; Hansen, Azure; Bigelow, Nicholas P.

2015-05-01

We create and study singular spin textures in pseudo-spin-1/2 BECs. A series of two-photon Raman interactions allows us to not only engineer the spinor wavefunction but also perform the equivalent of atomic polarimetry on the BEC. Adapting techniques from optical polarimetry, we can image two-dimensional maps of the atomic Stokes parameters, thereby fully reconstructing the atomic wavefunction. In a spin-1/2 system, we can represent the local spin superposition with ellipses in a Cartesian basis. The patterns that emerge from the major axes of the ellipses provide fingerprints of the singularities that enable us to classify them as lemons, stars, saddles, or spirals similar to classification schemes for singularities in singular optics, condensed matter, and liquid crystals. These techniques may facilitate the study of geometric Gouy phases in matter waves as well as provide an avenue for utilizing topological structures as quantum gates.

Heavy fields and gravity

NASA Astrophysics Data System (ADS)

Goon, Garrett

2017-01-01

We study the effects of heavy fields on 4D spacetimes with flat, de Sitter and anti-de Sitter asymptotics. At low energies, matter generates specific, calculable higher derivative corrections to the GR action which perturbatively alter the Schwarzschild-( A) dS family of solutions. The effects of massive scalars, Dirac spinors and gauge fields are each considered. The six-derivative operators they produce, such as ˜ R 3 terms, generate the leading corrections. The induced changes to horizon radii, Hawking temperatures and entropies are found. Modifications to the energy of large AdS black holes are derived by imposing the first law. An explicit demonstration of the replica trick is provided, as it is used to derive black hole and cosmological horizon entropies. Considering entropy bounds, it's found that scalars and fermions increase the entropy one can store inside a region bounded by a sphere of fixed size, but vectors lead to a decrease, oddly. We also demonstrate, however, that many of the corrections fall below the resolving power of the effective field theory and are therefore untrustworthy. Defining properties of black holes, such as the horizon area and Hawking temperature, prove to be remarkably robust against higher derivative gravitational corrections.

Massless conformal fields, AdS (d+1)/CFT d higher spin algebras and their deformations

DOE PAGES

Fernando, Sudarshan; Gunaydin, Murat

2016-02-04

Here, we extend our earlier work on the minimal unitary representation of SO(d, 2)and its deformations for d=4, 5and 6to arbitrary dimensions d. We show that there is a one-to-one correspondence between the minrep of SO(d, 2)and its deformations and massless conformal fields in Minkowskian spacetimes in ddimensions. The minrep describes a massless conformal scalar field, and its deformations describe massless conformal fields of higher spin. The generators of Joseph ideal vanish identically as operators for the quasiconformal realization of the minrep, and its enveloping algebra yields directly the standard bosonic AdS (d+1)/CFT d higher spin algebra. For deformed minrepsmore » the generators of certain deformations of Joseph ideal vanish as operators and their enveloping algebras lead to deformations of the standard bosonic higher spin algebra. In odd dimensions there is a unique deformation of the higher spin algebra corresponding to the spinor singleton. In even dimensions one finds infinitely many deformations of the higher spin algebra labelled by the eigenvalues of Casimir operator of the little group SO(d–2)for massless representations.« less

Birth of the GUP and its effect on the entropy of the universe in Lie-N-algebra

NASA Astrophysics Data System (ADS)

Sepehri, Alireza; Pradhan, Anirudh; Pincak, Richard; Rahaman, Farook; Beesham, A.; Ghaffary, Tooraj

In this paper, the origin of the generalized uncertainty principle (GUP) in an M-dimensional theory with Lie-N-algebra is considered. This theory which we name Generalized Lie-N-Algebra (GLNA)-theory can be reduced to M-theory with M = 11 and N = 3. In this theory, at the beginning, two energies with positive and negative signs are created from nothing and produce two types of branes with opposite quantum numbers and different numbers of timing dimensions. Coincidence with the birth of these branes, various derivatives of bosonic fields emerge in the action of the system which produce the r GUP for bosons. These branes interact with each other, compact and various derivatives of spinor fields appear in the action of the system which leads to the creation of the GUP for fermions. The previous predicted entropy of branes in the GUP is corrected as due to the emergence of higher orders of derivatives and different number of timing dimensions.

A sub-femtojoule electrical spin-switch based on optically trapped polariton condensates.

PubMed

Dreismann, Alexander; Ohadi, Hamid; Del Valle-Inclan Redondo, Yago; Balili, Ryan; Rubo, Yuri G; Tsintzos, Simeon I; Deligeorgis, George; Hatzopoulos, Zacharias; Savvidis, Pavlos G; Baumberg, Jeremy J

2016-10-01

Practical challenges to extrapolating Moore's law favour alternatives to electrons as information carriers. Two promising candidates are spin-based and all-optical architectures, the former offering lower energy consumption, the latter superior signal transfer down to the level of chip-interconnects. Polaritons-spinor quasi-particles composed of semiconductor excitons and microcavity photons-directly couple exciton spins and photon polarizations, combining the advantages of both approaches. However, their implementation for spintronics has been hindered because polariton spins can be manipulated only optically or by strong magnetic fields. Here we use an external electric field to directly control the spin of a polariton condensate, bias-tuning the emission polarization. The nonlinear spin dynamics offers an alternative route to switching, allowing us to realize an electrical spin-switch exhibiting ultralow switching energies below 0.5 fJ. Our results lay the foundation for development of devices based on the electro-optical control of coherent spin ensembles on a chip.

Implementation of the diagonalization-free algorithm in the self-consistent field procedure within the four-component relativistic scheme.

PubMed

Hrdá, Marcela; Kulich, Tomáš; Repiský, Michal; Noga, Jozef; Malkina, Olga L; Malkin, Vladimir G

2014-09-05

A recently developed Thouless-expansion-based diagonalization-free approach for improving the efficiency of self-consistent field (SCF) methods (Noga and Šimunek, J. Chem. Theory Comput. 2010, 6, 2706) has been adapted to the four-component relativistic scheme and implemented within the program package ReSpect. In addition to the implementation, the method has been thoroughly analyzed, particularly with respect to cases for which it is difficult or computationally expensive to find a good initial guess. Based on this analysis, several modifications of the original algorithm, refining its stability and efficiency, are proposed. To demonstrate the robustness and efficiency of the improved algorithm, we present the results of four-component diagonalization-free SCF calculations on several heavy-metal complexes, the largest of which contains more than 80 atoms (about 6000 4-spinor basis functions). The diagonalization-free procedure is about twice as fast as the corresponding diagonalization. Copyright © 2014 Wiley Periodicals, Inc.

Room-temperature Tamm-plasmon exciton-polaritons with a WSe2 monolayer

PubMed Central

Lundt, Nils; Klembt, Sebastian; Cherotchenko, Evgeniia; Betzold, Simon; Iff, Oliver; Nalitov, Anton V.; Klaas, Martin; Dietrich, Christof P.; Kavokin, Alexey V.; Höfling, Sven; Schneider, Christian

2016-01-01

Solid-state cavity quantum electrodynamics is a rapidly advancing field, which explores the frontiers of light–matter coupling. Metal-based approaches are of particular interest in this field, as they carry the potential to squeeze optical modes to spaces significantly below the diffraction limit. Transition metal dichalcogenides are ideally suited as the active material in cavity quantum electrodynamics, as they interact strongly with light at the ultimate monolayer limit. Here, we implement a Tamm-plasmon-polariton structure and study the coupling to a monolayer of WSe2, hosting highly stable excitons. Exciton-polariton formation at room temperature is manifested in the characteristic energy–momentum dispersion relation studied in photoluminescence, featuring an anti-crossing between the exciton and photon modes with a Rabi-splitting of 23.5 meV. Creating polaritonic quasiparticles in monolithic, compact architectures with atomic monolayers under ambient conditions is a crucial step towards the exploration of nonlinearities, macroscopic coherence and advanced spinor physics with novel, low-mass bosons. PMID:27796288

Holonomy of a principal composite bundle connection, non-Abelian geometric phases, and gauge theory of gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Viennot, David

We show that the holonomy of a connection defined on a principal composite bundle is related by a non-Abelian Stokes theorem to the composition of the holonomies associated with the connections of the component bundles of the composite. We apply this formalism to describe the non-Abelian geometric phase (when the geometric phase generator does not commute with the dynamical phase generator). We find then an assumption to obtain a new kind of separation between the dynamical and the geometric phases. We also apply this formalism to the gauge theory of gravity in the presence of a Dirac spinor field inmore » order to decompose the holonomy of the Lorentz connection into holonomies of the linear connection and of the Cartan connection.« less

On supersymmetric AdS6 solutions in 10 and 11 dimensions

NASA Astrophysics Data System (ADS)

Gutowski, J.; Papadopoulos, G.

2017-12-01

We prove a non-existence theorem for smooth, supersymmetric, warped AdS 6 solutions with connected, compact without boundary internal space in D = 11 and (massive) IIA supergravities. In IIB supergravity we show that if such AdS 6 solutions exist, then the NSNS and RR 3-form fluxes must be linearly independent and certain spinor bilinears must be appropriately restricted. Moreover we demonstrate that the internal space admits an so(3) action which leaves all the fields invariant and for smooth solutions the principal orbits must have co-dimension two. We also describe the topology and geometry of internal spaces that admit such a so(3) action and show that there are no solutions for which the internal space has topology F × S 2, where F is an oriented surface.

Born-Infeld extension of Lovelock brane gravity in the system of M0-branes and its application for the emergence of Pauli exclusion principle in BIonic superconductors

NASA Astrophysics Data System (ADS)

Sepehri, Alireza

2016-07-01

Recently, some authors (Cruz and Rojas, 2013 [1]) have constructed a Born-Infeld type action which may be written in terms of the Lovelock brane Lagrangians for a given dimension p. We reconsider their model in M-theory and study the process of birth and growth of nonlinear spinor and bosonic gravity during the construction of Mp-branes. Then, by application of this idea to BIonic system, we construct a BIonic superconductor in the background of nonlinear gravity. In this model, first, M0-branes link to each other and build an M5-brane and an anti-M5-brane connected by an M2-brane. M0-branes are zero dimensional objects that only scalars are attached to them. By constructing higher dimensional branes from M0-branes, gauge fields are produced. Also, if M0-branes don't link to each other completely, the symmetry of system is broken and fermions are created. The curvature produced by fermions has the opposite sign the curvature produced by gauge fields. Fermions on M5-branes and M2 plays the role of bridge between them. By passing time, M2 dissolves in M5's and nonlinear bosonic and spinor gravities are produced. By closing M5-branes towards each other, coupling of two identical fermions on two branes to each other causes that the square mass of their system becomes negative and some tachyonic states are created. For removing these tachyons, M5-branes compact, the sign of gravity between branes reverses, anti-gravity is produced which causes that branes and identical fermions get away from each other. This is the reason for the emergence of Pauli exclusion principle in Bionic system. Also, the spinor gravity vanishes and its energy builds a new M2 between M5-branes. We obtain the resistivity in this system and find that its value decreases by closing M5 branes to each other and shrinks to zero at colliding point of branes. This idea has different applications. For example, in cosmology, universes are located on M5-branes and M2-brane has the role of bridge between universes. When M5-branes become close to each other, this bridge dissolves in universes and causes that they expand. Also, when branes get away from each other, universes are contracted by compacting branes. The reason for flatness of universe in this system may be the neutralizing of curvature produced by gauge and scalar fields by the curvature produced by fermions. Using this idea in cuprates, we show that by decreasing temperature of system, branes which electrons live on it approach to each other in extra dimensions and superconductivity creates. Applying this idea in QCD, we calculate the potential between particles and anti-particles which is in good agreement with predicted potential for confined color particles. This means that one BIonic superconductor between quark and antiquark may be the main reason of confinement in QCD. Finally, in biological system, the emergence of superconductor between two neurons of two different brains via extra dimension leads to transmission of information between them and happening telepathy.

Electromagnetic unification of matter and force fields

NASA Astrophysics Data System (ADS)

John, Sarah

2004-05-01

Special relativity and quantum mechanics are descriptive of electromagnetic propagation in waveguides, with mass analogous to the cutoff frequency of a waveguide mode [S.John, Bull.Am.Phys.Soc. vol.39,no.2,1254 (1994)]. It is further postulated herein that all spin 1/2 matter (necessarily massive) and spin 1 force fields have their origin in the electromagnetic fields E and B. This concept is not new. Majorana, among others have obtained electromagnetic representations of Dirac-like equations valid for the zero-mass case. Here, the spinor representation of the Maxwell equations, as given by Sallhofer, is extended to oscillatory fields with propagation constant m to obtain, in the absence of charge and current densities, the coupled equation (M. hatp + β E)ψ = 0 , where M = diag[ M σ, M^* σ ] , β = offdiag[I,I] , ψ ^ = i ^dag ( σ. B0 ( p), σ. E_0(p)), and M=m+ip, with the energy-mass relation given by E^2 = M M . Further, it is shown that the interaction term of QED is a direct consequence of including the sources and currents of Maxwell equations. Qualitative field patterns for spin 1/2 and spin 1 states, such as the electron, neutrino, magnetic monopole, quarks, photon, and massive gauge bosons are suggested.

Celestial mechanics with geometric algebra

NASA Technical Reports Server (NTRS)

Hestenes, D.

1983-01-01

Geometric algebra is introduced as a general tool for Celestial Mechanics. A general method for handling finite rotations and rotational kinematics is presented. The constants of Kepler motion are derived and manipulated in a new way. A new spinor formulation of perturbation theory is developed.

Gravitational instantons admit hyper-Kähler structure

NASA Astrophysics Data System (ADS)

Aliev, A. N.; Nutku, Y.

1999-01-01

We construct the explicit form of three almost-complex structures that a Riemannian manifold with self-dual curvature admits and show that their Nijenhuis tensors vanish so that they are integrable. This proves that gravitational instantons with self-dual curvature admit hyper-Kähler structure. In order to arrive at the three vector-valued 1-forms defining almost-complex structure, we give a spinor description of real four-dimensional Riemannian manifolds with Euclidean signature in terms of two independent sets of two-component spinors. This is a version of the original Newman-Penrose formalism that is appropriate to the discussion of the mathematical, as well as physical properties of gravitational instantons. We shall build on the work of Goldblatt who first developed an NP formalism for gravitational instantons but we shall adopt it to differential forms in the NP basis to make the formalism much more compact. We shall show that the spin coefficients, connection 1-form, curvature 2-form, Ricci and Bianchi identities, as well as the Maxwell equations naturally split up into their self-dual and anti-self-dual parts corresponding to the two independent spin frames. We shall give the complex dyad as well as the spinor formulation of the almost-complex structures and show that they reappear under the guise of a triad basis for the Petrov classification of gravitational instantons. Completing the work of Salamon on hyper-Kähler structure, we show that the vanishing of the Nijenhuis tensor for all three almost-complex structures depends on the choice of a self-dual gauge for the connection which is guaranteed by virtue of the fact that the curvature 2-form is self-dual for gravitational instantons.

Zeroth order regular approximation approach to electric dipole moment interactions of the electron.

PubMed

Gaul, Konstantin; Berger, Robert

2017-07-07

A quasi-relativistic two-component approach for an efficient calculation of P,T-odd interactions caused by a permanent electric dipole moment of the electron (eEDM) is presented. The approach uses a (two-component) complex generalized Hartree-Fock and a complex generalized Kohn-Sham scheme within the zeroth order regular approximation. In applications to select heavy-elemental polar diatomic molecular radicals, which are promising candidates for an eEDM experiment, the method is compared to relativistic four-component electron-correlation calculations and confirms values for the effective electric field acting on the unpaired electron for RaF, BaF, YbF, and HgF. The calculations show that purely relativistic effects, involving only the lower component of the Dirac bi-spinor, are well described by treating only the upper component explicitly.

Zeroth order regular approximation approach to electric dipole moment interactions of the electron

NASA Astrophysics Data System (ADS)

Gaul, Konstantin; Berger, Robert

2017-07-01

A quasi-relativistic two-component approach for an efficient calculation of P ,T -odd interactions caused by a permanent electric dipole moment of the electron (eEDM) is presented. The approach uses a (two-component) complex generalized Hartree-Fock and a complex generalized Kohn-Sham scheme within the zeroth order regular approximation. In applications to select heavy-elemental polar diatomic molecular radicals, which are promising candidates for an eEDM experiment, the method is compared to relativistic four-component electron-correlation calculations and confirms values for the effective electric field acting on the unpaired electron for RaF, BaF, YbF, and HgF. The calculations show that purely relativistic effects, involving only the lower component of the Dirac bi-spinor, are well described by treating only the upper component explicitly.

A Projective-to-Conformal Fefferman-Type Construction

NASA Astrophysics Data System (ADS)

Hammerl, Matthias; Sagerschnig, Katja; Šilhan, Josef; Taghavi-Chabert, Arman; Zádník, Vojtĕch

2017-10-01

We study a Fefferman-type construction based on the inclusion of Lie groups SL(n+1) into Spin(n+1,n+1). The construction associates a split-signature (n,n)-conformal spin structure to a projective structure of dimension n. We prove the existence of a canonical pure twistor spinor and a light-like conformal Killing field on the constructed conformal space. We obtain a complete characterisation of the constructed conformal spaces in terms of these solutions to overdetermined equations and an integrability condition on the Weyl curvature. The Fefferman-type construction presented here can be understood as an alternative approach to study a conformal version of classical Patterson-Walker metrics as discussed in recent works by Dunajski-Tod and by the authors. The present work therefore gives a complete exposition of conformal Patterson-Walker metrics from the viewpoint of parabolic geometry.

Spacetime algebra as a powerful tool for electromagnetism

NASA Astrophysics Data System (ADS)

Dressel, Justin; Bliokh, Konstantin Y.; Nori, Franco

2015-08-01

We present a comprehensive introduction to spacetime algebra that emphasizes its practicality and power as a tool for the study of electromagnetism. We carefully develop this natural (Clifford) algebra of the Minkowski spacetime geometry, with a particular focus on its intrinsic (and often overlooked) complex structure. Notably, the scalar imaginary that appears throughout the electromagnetic theory properly corresponds to the unit 4-volume of spacetime itself, and thus has physical meaning. The electric and magnetic fields are combined into a single complex and frame-independent bivector field, which generalizes the Riemann-Silberstein complex vector that has recently resurfaced in studies of the single photon wavefunction. The complex structure of spacetime also underpins the emergence of electromagnetic waves, circular polarizations, the normal variables for canonical quantization, the distinction between electric and magnetic charge, complex spinor representations of Lorentz transformations, and the dual (electric-magnetic field exchange) symmetry that produces helicity conservation in vacuum fields. This latter symmetry manifests as an arbitrary global phase of the complex field, motivating the use of a complex vector potential, along with an associated transverse and gauge-invariant bivector potential, as well as complex (bivector and scalar) Hertz potentials. Our detailed treatment aims to encourage the use of spacetime algebra as a readily available and mature extension to existing vector calculus and tensor methods that can greatly simplify the analysis of fundamentally relativistic objects like the electromagnetic field.

The Chern-Simons Current in Systems of DNA-RNA Transcriptions

NASA Astrophysics Data System (ADS)

Capozziello, Salvatore; Pincak, Richard; Kanjamapornkul, Kabin; Saridakis, Emmanuel N.

2018-04-01

A Chern-Simons current, coming from ghost and anti-ghost fields of supersymmetry theory, can be used to define a spectrum of gene expression in new time series data where a spinor field, as alternative representation of a gene, is adopted instead of using the standard alphabet sequence of bases $A, T, C, G, U$. After a general discussion on the use of supersymmetry in biological systems, we give examples of the use of supersymmetry for living organism, discuss the codon and anti-codon ghost fields and develop an algebraic construction for the trash DNA, the DNA area which does not seem active in biological systems. As a general result, all hidden states of codon can be computed by Chern-Simons 3 forms. Finally, we plot a time series of genetic variations of viral glycoprotein gene and host T-cell receptor gene by using a gene tensor correlation network related to the Chern-Simons current. An empirical analysis of genetic shift, in host cell receptor genes with separated cluster of gene and genetic drift in viral gene, is obtained by using a tensor correlation plot over time series data derived as the empirical mode decomposition of Chern-Simons current.

Anomaly on Superspace of Time Series Data

NASA Astrophysics Data System (ADS)

Capozziello, Salvatore; Pincak, Richard; Kanjamapornkul, Kabin

2017-11-01

We apply the G-theory and anomaly of ghost and antighost fields in the theory of supersymmetry to study a superspace over time series data for the detection of hidden general supply and demand equilibrium in the financial market. We provide proof of the existence of a general equilibrium point over 14 extradimensions of the new G-theory compared with the M-theory of the 11 dimensions model of Edward Witten. We found that the process of coupling between nonequilibrium and equilibrium spinor fields of expectation ghost fields in the superspace of time series data induces an infinitely long exact sequence of cohomology from a short exact sequence of moduli state space model. If we assume that the financial market is separated into two topological spaces of supply and demand as the D-brane and anti-D-brane model, then we can use a cohomology group to compute the stability of the market as a stable point of the general equilibrium of the interaction between D-branes of the market. We obtain the result that the general equilibrium will exist if and only if the 14th Batalin-Vilkovisky cohomology group with the negative dimensions underlying 14 major hidden factors influencing the market is zero.

The Coupling of Gravity to Spin and Electromagnetism

NASA Astrophysics Data System (ADS)

Finster, Felix; Smoller, Joel; Yau, Shing-Tung

The coupled Einstein-Dirac-Maxwell equations are considered for a static, spherically symmetric system of two fermions in a singlet spinor state. Stable soliton-like solutions are shown to exist, and we discuss the regularizing effect of gravity from a Feynman diagram point of view.

Bell Inequality, Einstein-Podolsky-Rosen Steering, and Quantum Metrology with Spinor Bose-Einstein Condensates.

PubMed

Wasak, Tomasz; Chwedeńczuk, Jan

2018-04-06

We propose an experiment, where the Bell inequality is violated in a many-body system of massive particles. The source of correlated atoms is a spinor F=1 Bose-Einstein condensate residing in an optical lattice. We characterize the complete procedure-the local operations, the measurements, and the inequality-necessary to run the Bell test. We show how the degree of violation of the Bell inequality depends on the strengths of the two-body correlations and on the number of scattered pairs. We show that the system can be used to demonstrate the Einstein-Podolsky-Rosen paradox. Also, the scattered pairs are an excellent many-body resource for the quantum-enhanced metrology. Our results apply to any multimode system where the spin-changing collision drives the scattering into separate regions. The presented inquiry shows that such a system is versatile as it can be used for the tests of nonlocality, quantum metrology, and quantum information.

Coupled spin and electron-phonon interaction at the Tl/Si(111) surface from relativistic first-principles calculations

NASA Astrophysics Data System (ADS)

Garcia-Goiricelaya, Peio; Gurtubay, Idoia G.; Eiguren, Asier

2018-05-01

We investigate the role played by the electron spin and the spin-orbit interaction in the exceptional electron-phonon coupling at the Tl/Si(111) surface. Our first-principles calculations demonstrate that the particular spin pattern of this system dominates the whole low-energy electron-phonon physics, which is remarkably explained by forbidden spin-spin scattering channels. In particular, we show that the strength of the electron-phonon coupling appears drastically weakened for surface states close to the K ¯ and K'¯ valleys, which is unambiguously attributed to the spin polarization through the associated modulation due to the spinor overlaps. However, close to the Γ ¯ point, the particular spin pattern in this area is less effective in damping the electron-phonon matrix elements, and the result is an exceptional strength of the electron-phonon coupling parameter λ ˜1.4 . These results are rationalized by a simple model for the electron-phonon matrix elements including the spinor terms.

Quantum fluctuations and gapped Goldstone modes in spinor Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Beekman, Aron

2015-03-01

The classical Heisenberg ferromagnet is an exact eigenstate of the quantum Hamiltonian and therefore has no quantum fluctuations. Furthermore it has a reduced number of Goldstone modes, an order parameter that is itself a symmetry generator, is a highest-weight state for the spin algebra, and has no tower of states of vanishing energy. We derive the connection between all these properties and provide general criteria for their presence in other spontaneously-broken symmetry states. The phletora of groundstates in spinor Bose-Einstein condensates is an ideal testing ground for these predictions. In particular the phases with non-maximal polarization (e.g. the F-phase in spin-3 condensates) have an additional gapped mode that is a partner to the quadratically dispersing Goldstone mode, as compared to the maximally polarized, ferromagnetic phase. Furthermore there is a fundamental limit to the coherence time of superpositions in the non-maximally polarized state, which should manifest itself for small-size systems.

Group Theory with Applications in Chemical Physics

NASA Astrophysics Data System (ADS)

Jacobs, Patrick

2005-10-01

Group Theory is an indispensable mathematical tool in many branches of chemistry and physics. This book provides a self-contained and rigorous account on the fundamentals and applications of the subject to chemical physics, assuming no prior knowledge of group theory. The first half of the book focuses on elementary topics, such as molecular and crystal symmetry, whilst the latter half is more advanced in nature. Discussions on more complex material such as space groups, projective representations, magnetic crystals and spinor bases, often omitted from introductory texts, are expertly dealt with. With the inclusion of numerous exercises and worked examples, this book will appeal to advanced undergraduates and beginning graduate students studying physical sciences and is an ideal text for use on a two-semester course. An introductory and advanced text that comprehensively covers fundamentals and applications of group theory in detail Suitable for a two-semester course with numerous worked examples and problems Includes several topics often omitted from introductory texts, such as rotation group, space groups and spinor bases

Bell Inequality, Einstein-Podolsky-Rosen Steering, and Quantum Metrology with Spinor Bose-Einstein Condensates

NASA Astrophysics Data System (ADS)

Wasak, Tomasz; Chwedeńczuk, Jan

2018-04-01

We propose an experiment, where the Bell inequality is violated in a many-body system of massive particles. The source of correlated atoms is a spinor F =1 Bose-Einstein condensate residing in an optical lattice. We characterize the complete procedure—the local operations, the measurements, and the inequality—necessary to run the Bell test. We show how the degree of violation of the Bell inequality depends on the strengths of the two-body correlations and on the number of scattered pairs. We show that the system can be used to demonstrate the Einstein-Podolsky-Rosen paradox. Also, the scattered pairs are an excellent many-body resource for the quantum-enhanced metrology. Our results apply to any multimode system where the spin-changing collision drives the scattering into separate regions. The presented inquiry shows that such a system is versatile as it can be used for the tests of nonlocality, quantum metrology, and quantum information.

Rotational dynamics with geometric algebra

NASA Technical Reports Server (NTRS)

Hestenes, D.

1983-01-01

A new spinor formulation of rotational dynamics is developed. A general theorem is established reducing the theory of the symmetric top to that of the spherical top. The classical problems of Lagrange and Poinsot are treated in detail, along with a modern application to the theory of magnetic resonance.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanna, T.; Sakkaravarthi, K.; Kumar, C. Senthil

In this paper, we have studied the integrability nature of a system of three-coupled Gross-Pitaevskii type nonlinear evolution equations arising in the context of spinor Bose-Einstein condensates by applying the Painleve singularity structure analysis. We show that only for two sets of parametric choices, corresponding to the known integrable cases, the system passes the Painleve test.

Parametric excitation and squeezing in a many-body spinor condensate

PubMed Central

Hoang, T. M.; Anquez, M.; Robbins, B. A.; Yang, X. Y.; Land, B. J.; Hamley, C. D.; Chapman, M. S.

2016-01-01

Atomic spins are usually manipulated using radio frequency or microwave fields to excite Rabi oscillations between different spin states. These are single-particle quantum control techniques that perform ideally with individual particles or non-interacting ensembles. In many-body systems, inter-particle interactions are unavoidable; however, interactions can be used to realize new control schemes unique to interacting systems. Here we demonstrate a many-body control scheme to coherently excite and control the quantum spin states of an atomic Bose gas that realizes parametric excitation of many-body collective spin states by time varying the relative strength of the Zeeman and spin-dependent collisional interaction energies at multiples of the natural frequency of the system. Although parametric excitation of a classical system is ineffective from the ground state, we show that in our experiment, parametric excitation from the quantum ground state leads to the generation of quantum squeezed states. PMID:27044675

Spin-flip transitions and departure from the Rashba model in the Au(111) surface

NASA Astrophysics Data System (ADS)

Ibañez-Azpiroz, Julen; Bergara, Aitor; Sherman, E. Ya.; Eiguren, Asier

2013-09-01

We present a detailed analysis of the spin-flip excitations induced by a periodic time-dependent electric field in the Rashba prototype Au(111) noble metal surface. Our calculations incorporate the full spinor structure of the spin-split surface states and employ a Wannier-based scheme for the spin-flip matrix elements. We find that the spin-flip excitations associated with the surface states exhibit an strong dependence on the electron momentum magnitude, a feature that is absent in the standard Rashba model [E. I. Rashba, Sov. Phys. Solid State 2, 1109 (1960)]. Furthermore, we demonstrate that the maximum of the calculated spin-flip absorption rate is about twice the model prediction. These results show that, although the Rashba model accurately describes the spectrum and spin polarization, it does not fully account for the dynamical properties of the surface states.

Parametric excitation and squeezing in a many-body spinor condensate

NASA Astrophysics Data System (ADS)

Hoang, T. M.; Anquez, M.; Robbins, B. A.; Yang, X. Y.; Land, B. J.; Hamley, C. D.; Chapman, M. S.

2016-04-01

Atomic spins are usually manipulated using radio frequency or microwave fields to excite Rabi oscillations between different spin states. These are single-particle quantum control techniques that perform ideally with individual particles or non-interacting ensembles. In many-body systems, inter-particle interactions are unavoidable; however, interactions can be used to realize new control schemes unique to interacting systems. Here we demonstrate a many-body control scheme to coherently excite and control the quantum spin states of an atomic Bose gas that realizes parametric excitation of many-body collective spin states by time varying the relative strength of the Zeeman and spin-dependent collisional interaction energies at multiples of the natural frequency of the system. Although parametric excitation of a classical system is ineffective from the ground state, we show that in our experiment, parametric excitation from the quantum ground state leads to the generation of quantum squeezed states.

The bulk, surface and corner free energies of the square lattice Ising model

NASA Astrophysics Data System (ADS)

Baxter, R. J.

2017-01-01

We use Kaufman’s spinor method to calculate the bulk, surface and corner free energies {f}{{b}},{f}{{s}},{f}{{s}}\\prime ,{f}{{c}} of the anisotropic square lattice zero-field Ising model for the ordered ferromagnetic case. For {f}{{b}},{f}{{s}},{f}{{s}}\\prime our results of course agree with the early work of Onsager, McCoy and Wu. We also find agreement with the conjectures made by Vernier and Jacobsen (VJ) for the isotropic case. We note that the corner free energy f c depends only on the elliptic modulus k that enters the working, and not on the argument v, which means that VJ’s conjecture applies for the full anisotropic model. The only aspect of this paper that is new is the actual derivation of f c, but by reporting all four free energies together we can see interesting structures linking them.

BOOK REVIEW: Supersymmetry: Theory, Experiment and Cosmology

NASA Astrophysics Data System (ADS)

Jones, Tim

2008-06-01

This volume presents a comprehensive introduction to supersymmetry, concentrating mainly on the Minimal Supersymmetric Standard Model (MSSM) and its possible embedding in a grand unified theory, but also including material on supergravity, non-perturbative aspects of supersymmetry, string theory and cosmology. There is an excellent self-contained appendix on the standard model which could be read first; other appendices provide introductions to spinor representations of the Lorentz group, superfields, and cosmology, and there is a short appendix listing the MSSM renormalisation group beta-functions. The appendices in fact occupy over a quarter of the volume. Substantial knowledge of quantum field theory is required of the reader; and also a working knowledge of group theory as employed in the construction of particle physics models: while there is some useful material on this in the section on grand unification, an appendix on it might perhaps have been a useful addition. Supersymmetry is introduced via the particle physicist's concern with the hierarchy problem and developed in the component formalism beginning with the Wess Zumino model and proceeding to supersymmetric gauge theories. The treatment is detailed and authoritative; the author has 25 years of high-level research experience in the area and it shows. The level of presentation is high, and difficult concepts are explained clearly. The examples and associated hints are excellent. One topic I would have liked to see more on is the renormalisation of supersymmetric theories; presentation of the explicit calculation of the anomalous dimension of a chiral superfield (gamma) at one loop for at least the Wess Zumino model might perhaps have been pedagogically useful. Associated, perhaps, with this omission is an inconsistency in the definition of gamma; the sign of gamma in the treatment in section 8.3.2 clearly differs from its sign in the appendix section E.3. In the text the formalism of supersymmetry is developed mainly in terms of four-component Majorana spinors, while use of two-component spinors is relegated to the appendices, where the author valiantly presents results in a manner facilitating translation between different conventions, which is very useful. In the main text, however, the reader might even be led to feel that the Wess Zumino model actions for a Majorana fermion on the one hand and a chiral fermion on the other are different theories, whereas in fact one can of course be rewritten as the other. I feel that the two-component formalism could have been profitably introduced at an earlier stage and used more consistently. The book concludes with discussions of two 'challenges' to supersymmetry, as presented by the flavour problem and the cosmological constant. These are full of interesting and (indeed) challenging material, at the frontier of present-day research. This is an excellent and up-to-date book, and very timely vis-à-vis the Large Hadron Collider. It would make an excellent graduate text for graduate students in particle theory. 'Road-maps' for high energy experimentalists and cosmologists are also provided; however for experimentalists a text with more in the way of, for example, explicit calculations of cross-sections would probably be more useful. To summarise: minor quibbles aside, a fine book with a wealth of exciting material, and to be thoroughly recommended to any theoretically-inclined graduate student who has done a field theory course and wants to really get to grips with any aspect of supersymmetry.

Two-dimensional symbiotic solitons and vortices in binary condensates with attractive cross-species interaction

PubMed Central

Ma, Xuekai; Driben, Rodislav; Malomed, Boris A.; Meier, Torsten; Schumacher, Stefan

2016-01-01

We consider a two-dimensional (2D) two-component spinor system with cubic attraction between the components and intra-species self-repulsion, which may be realized in atomic Bose-Einstein condensates, as well as in a quasi-equilibrium condensate of microcavity polaritons. Including a 2D spatially periodic potential, which is necessary for the stabilization of the system against the critical collapse, we use detailed numerical calculations and an analytical variational approximation (VA) to predict the existence and stability of several types of 2D symbiotic solitons in the spinor system. Stability ranges are found for symmetric and asymmetric symbiotic fundamental solitons and vortices, including hidden-vorticity (HV) modes, with opposite vorticities in the two components. The VA produces exceptionally accurate predictions for the fundamental solitons and vortices. The fundamental solitons, both symmetric and asymmetric ones, are completely stable, in either case when they exist as gap solitons or regular ones. The symmetric and asymmetric vortices are stable if the inter-component attraction is stronger than the intra-species repulsion, while the HV modes have their stability region in the opposite case. PMID:27703235

Quantum correlations are weaved by the spinors of the Euclidean primitives

PubMed Central

2018-01-01

The exceptional Lie group E8 plays a prominent role in both mathematics and theoretical physics. It is the largest symmetry group associated with the most general possible normed division algebra, namely, that of the non-associative real octonions, which—thanks to their non-associativity—form the only possible closed set of spinors (or rotors) that can parallelize the 7-sphere. By contrast, here we show how a similar 7-sphere also arises naturally from the algebraic interplay of the graded Euclidean primitives, such as points, lines, planes and volumes, which characterize the three-dimensional conformal geometry of the ambient physical space, set within its eight-dimensional Clifford-algebraic representation. Remarkably, the resulting algebra remains associative, and allows us to understand the origins and strengths of all quantum correlations locally, in terms of the geometry of the compactified physical space, namely, that of a quaternionic 3-sphere, S3, with S7 being its algebraic representation space. Every quantum correlation can thus be understood as a correlation among a set of points of this S7, computed using manifestly local spinors within S3, thereby extending the stringent bounds of ±2 set by Bell inequalities to the bounds of ±22 on the strengths of all possible strong correlations, in the same quantitatively precise manner as that predicted within quantum mechanics. The resulting geometrical framework thus overcomes Bell’s theorem by producing a strictly deterministic and realistic framework that allows a locally causal understanding of all quantum correlations, without requiring either remote contextuality or backward causation. We demonstrate this by first proving a general theorem concerning the geometrical origins of the correlations predicted by arbitrarily entangled quantum states, and then reproducing the correlations predicted by the EPR-Bohm and the GHZ states. The raison d’être of strong correlations turns out to be the Möbius-like twists in the Hopf bundles of S3 and S7. PMID:29893385

Understanding Quaternions and the Dirac Belt Trick

ERIC Educational Resources Information Center

Staley, Mark

2010-01-01

The Dirac belt trick is often employed in physics classrooms to show that a 2n rotation is not topologically equivalent to the absence of rotation whereas a 4n rotation is, mirroring a key property of quaternions and their isomorphic cousins, spinors. The belt trick can leave the student wondering if a real understanding of quaternions and spinors…

A model of comprehensive unification

NASA Astrophysics Data System (ADS)

Reig, Mario; Valle, José W. F.; Vaquera-Araujo, C. A.; Wilczek, Frank

2017-11-01

Comprehensive - that is, gauge and family - unification using spinors has many attractive features, but it has been challenged to explain chirality. Here, by combining an orbifold construction with more traditional ideas, we address that difficulty. Our candidate model features three chiral families and leads to an acceptable result for quantitative unification of couplings. A potential target for accelerator and astronomical searches emerges.

Local U(2,2) symmetry in relativistic quantum mechanics

NASA Astrophysics Data System (ADS)

Finster, Felix

1998-12-01

Local gauge freedom in relativistic quantum mechanics is derived from a measurement principle for space and time. For the Dirac equation, one obtains local U(2,2) gauge transformations acting on the spinor index of the wave functions. This local U(2,2) symmetry allows a unified description of electrodynamics and general relativity as a classical gauge theory.

Generalized wave operators, weighted Killing fields, and perturbations of higher dimensional spacetimes

NASA Astrophysics Data System (ADS)

Araneda, Bernardo

2018-04-01

We present weighted covariant derivatives and wave operators for perturbations of certain algebraically special Einstein spacetimes in arbitrary dimensions, under which the Teukolsky and related equations become weighted wave equations. We show that the higher dimensional generalization of the principal null directions are weighted conformal Killing vectors with respect to the modified covariant derivative. We also introduce a modified Laplace–de Rham-like operator acting on tensor-valued differential forms, and show that the wave-like equations are, at the linear level, appropriate projections off shell of this operator acting on the curvature tensor; the projection tensors being made out of weighted conformal Killing–Yano tensors. We give off shell operator identities that map the Einstein and Maxwell equations into weighted scalar equations, and using adjoint operators we construct solutions of the original field equations in a compact form from solutions of the wave-like equations. We study the extreme and zero boost weight cases; extreme boost corresponding to perturbations of Kundt spacetimes (which includes near horizon geometries of extreme black holes), and zero boost to static black holes in arbitrary dimensions. In 4D our results apply to Einstein spacetimes of Petrov type D and make use of weighted Killing spinors.

New Quantum Diffusion Monte Carlo Method for strong field time dependent problems

NASA Astrophysics Data System (ADS)

Kalinski, Matt

2017-04-01

We have recently formulated the Quantum Diffusion Quantum Monte Carlo (QDMC) method for the solution of the time-dependent Schrödinger equation when it is equivalent to the reaction-diffusion system coupled by the highly nonlinear potentials of the type of Shay. Here we formulate a new Time Dependent QDMC method free of the nonlinearities described by the constant stochastic process of the coupled diffusion with transmutation. As before two kinds of diffusing particles (color walkers) are considered but which can further also transmute one into the other. Each of the species undergoes the hypothetical Einstein random walk progression with transmutation. The progressed particles transmute into the particles of the other kind before contributing to or annihilating the other particles density. This fully emulates the Time Dependent Schrödinger equation for any number of quantum particles. The negative sign of the real and the imaginary parts of the wave function is handled by the ``spinor'' densities carrying the sign as the degree of freedom. We apply the method for the exact time-dependent observation of our discovered two-electron Langmuir configurations in the magnetic and circularly polarized fields.

Dirac field and gravity in NC SO(2,3)_\\star model

NASA Astrophysics Data System (ADS)

Gočanin, Dragoljub; Radovanović, Voja

2018-03-01

Action for the Dirac spinor field coupled to gravity on noncommutative (NC) Moyal-Weyl spacetime is obtained without prior knowledge of the metric tensor. We emphasize gauge origins of gravity and its interaction with fermions by demonstrating that a classical action invariant under SO(2, 3) gauge transformations can be exactly reduced to the Dirac action in curved spacetime after breaking the original symmetry down to the local Lorentz SO(1, 3) symmetry. The commutative SO(2, 3) invariant action can be straightforwardly deformed via Moyal-Weyl \\star -product to its NC SO(2,3)_\\star invariant version which can be expanded perturbatively in powers of the deformation parameter using the Seiberg-Witten map. The NC gravity-matter couplings in the expansion arise as an effect of the gauge symmetry breaking. We calculate in detail the first order NC correction to the classical Dirac action in curved spacetime and show that it does not vanish. Moreover, linear NC effects are apparent even in flat spacetime. We analyse NC deformation of the Dirac equation, Feynman propagator and dispersion relation for electrons in Minkowski spacetime and conclude that constant NC background acts as a birefringent medium for electrons propagating in it.

The Chern-Simons current in time series of knots and links in proteins

NASA Astrophysics Data System (ADS)

Capozziello, Salvatore; Pincak, Richard

2018-06-01

A superspace model of knots and links for DNA time series data is proposed to take into account the feedback loop from docking to undocking state of protein-protein interactions. In particular, the direction of interactions between the 8 hidden states of DNA is considered. It is a E8 ×E8 unified spin model where the genotype, from active and inactive side of DNA time data series, can be considered for any living organism. The mathematical model is borrowed from loop-quantum gravity and adapted to biology. It is used to derive equations for gene expression describing transitions from ground to excited states, and for the 8 coupling states between geneon and anti-geneon transposon and retrotransposon in trash DNA. Specifically, we adopt a modified Grothendieck cohomology and a modified Khovanov cohomology for biology. The result is a Chern-Simons current in (8 + 3) extradimensions of a given unoriented supermanifold with ghost fields of protein structures. The 8 dimensions come from the 8 hidden states of spinor field of genetic code. The extradimensions come from the 3 types of principle fiber bundle in the secondary protein.

Geometric Algebra for Physicists

NASA Astrophysics Data System (ADS)

Doran, Chris; Lasenby, Anthony

2007-11-01

Preface; Notation; 1. Introduction; 2. Geometric algebra in two and three dimensions; 3. Classical mechanics; 4. Foundations of geometric algebra; 5. Relativity and spacetime; 6. Geometric calculus; 7. Classical electrodynamics; 8. Quantum theory and spinors; 9. Multiparticle states and quantum entanglement; 10. Geometry; 11. Further topics in calculus and group theory; 12. Lagrangian and Hamiltonian techniques; 13. Symmetry and gauge theory; 14. Gravitation; Bibliography; Index.

Gluing operation and form factors of local operators in N = 4 Super Yang-Mills theory

NASA Astrophysics Data System (ADS)

Bolshov, A. E.

2018-04-01

The gluing operation is an effective way to get form factors of both local and non-local operators starting from different representations of on-shell scattering amplitudes. In this paper it is shown how it works on the example of form factors of operators from stress-tensor operator supermultiplet in Grassmannian and spinor helicity representations.

I in generalized supergravity

NASA Astrophysics Data System (ADS)

Araujo, T.; Ó Colgáin, E.; Sakamoto, J.; Sheikh-Jabbari, M. M.; Yoshida, K.

2017-11-01

We showed in previous work that for homogeneous Yang-Baxter (YB) deformations of AdS_5× S^5 the open string metric and coupling and as a result the closed string density e^{-2 Φ } √{g} remain undeformed. In this work, in addition to extending these results to the deformation associated with the modified CYBE or η -deformation, we identify the Page forms as the open string counterpart for RR fields and demonstrate case by case that the non-zero Page forms remain invariant under YB deformations. We give a physical meaning to the Killing vector I of generalized supergravity and show for all YB deformations: (1) I appears as a current for the center of mass motion on the worldvolume of a D-brane probing the background, (2) I is equal to the divergence of the noncommutativity parameter, (3) I exhibits "holographic" behavior where the radial component of I vanishes at the AdS boundary and (4) in pure spinor formalism I is related to a certain state in the BRST cohomology.

Introduction to the special issue Hermann Weyl and the philosophy of the 'New Physics'

NASA Astrophysics Data System (ADS)

De Bianchi, Silvia; Catren, Gabriel

2018-02-01

This Special Issue Hermann Weyl and the Philosophy of the 'New Physics' has two main objectives: first, to shed fresh light on the relevance of Weyl's work for modern physics and, second, to evaluate the importance of Weyl's work and ideas for contemporary philosophy of physics. Regarding the first objective, this Special Issue emphasizes aspects of Weyl's work (e.g. his work on spinors in n dimensions) whose importance has recently been emerging in research fields across both mathematical and experimental physics, as well as in the history and philosophy of physics. Regarding the second objective, this Special Issue addresses the relevance of Weyl's ideas regarding important open problems in the philosophy of physics, such as the problem of characterizing scientific objectivity and the problem of providing a satisfactory interpretation of fundamental symmetries in gauge theories and quantum mechanics. In this Introduction, we sketch the state of the art in Weyl studies and we summarize the content of the contributions to the present volume.

Republication of: Contributions to the theory of pure gravitational radiation. Exact solutions of the field equations of the general theory of relativity II

NASA Astrophysics Data System (ADS)

Jordan, Pascual; Ehlers, Jürgen; Sachs, Rainer K.

2013-12-01

This is an English translation of a paper by Pascual Jordan, Juergen Ehlers and Rainer Sachs, first published in 1961 in the proceedings of the Academy of Sciences and Literature in Mainz (Germany). The original paper was part 2 of a five-part series of articles containing the first summary of knowledge about exact solutions of Einstein's equations found until then. (Parts 1 and 4 of the series have already been reprinted, parts 3 and 5 will be printed as Golden Oldies in near future.) This second paper discusses the geometry of geodesic null congruences, the algebraic classification of the Weyl tensor by spinor methods, and applies these to a study of the propagation of gravitational and electromagnetic radiation. It has been selected by the Editors of General Relativity and Gravitation for republication in the Golden Oldies series of the journal. The republication is accompanied by an editorial note written by Malcolm A. H. MacCallum and Wolfgang Kundt.

Expanding space-time and variable vacuum energy

NASA Astrophysics Data System (ADS)

Parmeggiani, Claudio

2017-08-01

The paper describes a cosmological model which contemplates the presence of a vacuum energy varying, very slightly (now), with time. The constant part of the vacuum energy generated, some 6 Gyr ago, a deceleration/acceleration transition of the metric expansion; so now, in an aged Universe, the expansion is inexorably accelerating. The vacuum energy varying part is instead assumed to be eventually responsible of an acceleration/deceleration transition, which occurred about 14 Gyr ago; this transition has a dynamic origin: it is a consequence of the general relativistic Einstein-Friedmann equations. Moreover, the vacuum energy (constant and variable) is here related to the zero-point energy of some quantum fields (scalar, vector, or spinor); these fields are necessarily described in a general relativistic way: their structure depends on the space-time metric, typically non-flat. More precisely, the commutators of the (quantum field) creation/annihilation operators are here assumed to depend on the local value of the space-time metric tensor (and eventually of its curvature); furthermore, these commutators rapidly decrease for high momentum values and they reduce to the standard ones for a flat metric. In this way, the theory is ”gravitationally” regularized; in particular, the zero-point (vacuum) energy density has a well defined value and, for a non static metric, depends on the (cosmic) time. Note that this varying vacuum energy can be negative (Fermi fields) and that a change of its sign typically leads to a minimum for the metric expansion factor (a ”bounce”).

Superconformal quantum field theory in curved spacetime

NASA Astrophysics Data System (ADS)

de Medeiros, Paul; Hollands, Stefan

2013-09-01

By conformally coupling vector and hyper multiplets in Minkowski space, we obtain a class of field theories with extended rigid conformal supersymmetry on any Lorentzian 4-manifold admitting twistor spinors. We construct the conformal symmetry superalgebras which describe classical symmetries of these theories and derive an appropriate BRST operator in curved spacetime. In the process, we elucidate the general framework of cohomological algebra which underpins the construction. We then consider the corresponding perturbative quantum field theories. In particular, we examine the conditions necessary for conformal supersymmetries to be preserved at the quantum level, i.e. when the BRST operator commutes with the perturbatively defined S-matrix, which ensures superconformal invariance of amplitudes. To this end, we prescribe a renormalization scheme for time-ordered products that enter the perturbative S-matrix and show that such products obey certain Ward identities in curved spacetime. These identities allow us to recast the problem in terms of the cohomology of the BRST operator. Through a careful analysis of this cohomology, and of the renormalization group in curved spacetime, we establish precise criteria which ensure that all conformal supersymmetries are preserved at the quantum level. As a by-product, we provide a rigorous proof that the beta-function for such theories is one-loop exact. We also briefly discuss the construction of chiral rings and the role of non-perturbative effects in curved spacetime.

Irreversibility and higher-spin conformal field theory

NASA Astrophysics Data System (ADS)

Anselmi, Damiano

2000-08-01

I discuss the properties of the central charges c and a for higher-derivative and higher-spin theories (spin 2 included). Ordinary gravity does not admit a straightforward identification of c and a in the trace anomaly, because it is not conformal. On the other hand, higher-derivative theories can be conformal, but have negative c and a. A third possibility is to consider higher-spin conformal field theories. They are not unitary, but have a variety of interesting properties. Bosonic conformal tensors have a positive-definite action, equal to the square of a field strength, and a higher-derivative gauge invariance. There exists a conserved spin-2 current (not the canonical stress tensor) defining positive central charges c and a. I calculate the values of c and a and study the operator-product structure. Higher-spin conformal spinors have no gauge invariance, admit a standard definition of c and a and can be coupled to Abelian and non-Abelian gauge fields in a renormalizable way. At the quantum level, they contribute to the one-loop beta function with the same sign as ordinary matter, admit a conformal window and non-trivial interacting fixed points. There are composite operators of high spin and low dimension, which violate the Ferrara-Gatto-Grillo theorem. Finally, other theories, such as conformal antisymmetric tensors, exhibit more severe internal problems. This research is motivated by the idea that fundamental quantum field theories should be renormalization-group (RG) interpolations between ultraviolet and infrared conformal fixed points, and quantum irreversibility should be a general principle of nature.

Notes on Translational and Rotational Properties of Tensor Fields in Relativistic Quantum Mechanics

NASA Astrophysics Data System (ADS)

Dvoeglazov, V. V.

Recently, several discussions on the possible observability of 4-vector fields have been published in literature. Furthermore, several authors recently claimed existence of the helicity=0 fundamental field. We re-examine the theory of antisymmetric tensor fields and 4-vector potentials. We study the massless limits. In fact, a theoretical motivation for this venture is the old papers of Ogievetskiĭ and Polubarinov, Hayashi, and Kalb and Ramond. Ogievetskiĭ and Polubarinov proposed the concept of the notoph, whose helicity properties are complementary to those of the photon. We analyze the quantum field theory with taking into account mass dimensions of the notoph and the photon. It appears to be possible to describe both photon and notoph degrees of freedom on the basis of the modified Bargmann-Wigner formalism for the symmetric second-rank spinor. Next, we proceed to derive equations for the symmetric tensor of the second rank on the basis of the Bargmann-Wigner formalism in a straightforward way. The symmetric multispinor of the fourth rank is used. Due to serious problems with the interpretation of the results obtained on using the standard procedure we generalize it and obtain the spin-2 relativistic equations, which are consistent with the general relativity. Thus, in fact we deduced the gravitational field equations from relativistic quantum mechanics. The relations of this theory with the scalar-tensor theories of gravitation and f(R) are discussed. Particular attention has been paid to the correct definitions of the energy-momentum tensor and other Nöther currents in the electromagnetic theory, the relativistic theory of gravitation, the general relativity, and their generalizations. We estimate possible interactions, fermion-notoph, graviton-notoph, photon-notoph, and we conclude that they can probably be seen in experiments in the next few years.

Multiscale analysis of the CMB temperature derivatives

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marcos-Caballero, A.; Martínez-González, E.; Vielva, P., E-mail: marcos@ifca.unican.es, E-mail: martinez@ifca.unican.es, E-mail: vielva@ifca.unican.es

2017-02-01

We study the Planck CMB temperature at different scales through its derivatives up to second order, which allows one to characterize the local shape and isotropy of the field. The problem of having an incomplete sky in the calculation and statistical characterization of the derivatives is addressed in the paper. The analysis confirms the existence of a low variance in the CMB at large scales, which is also noticeable in the derivatives. Moreover, deviations from the standard model in the gradient, curvature and the eccentricity tensor are studied in terms of extreme values on the data. As it is expected,more » the Cold Spot is detected as one of the most prominent peaks in terms of curvature, but additionally, when the information of the temperature and its Laplacian are combined, another feature with similar probability at the scale of 10{sup o} is also observed. However, the p -value of these two deviations increase above the 6% when they are referred to the variance calculated from the theoretical fiducial model, indicating that these deviations can be associated to the low variance anomaly. Finally, an estimator of the directional anisotropy for spinorial quantities is introduced, which is applied to the spinors derived from the field derivatives. An anisotropic direction whose probability is <1% is detected in the eccentricity tensor.« less

On-demand dark soliton train manipulation in a spinor polariton condensate.

PubMed

Pinsker, F; Flayac, H

2014-04-11

We theoretically demonstrate the generation of dark soliton trains in a one-dimensional exciton-polariton condensate within experimentally accessible schemes. In particular, we show that the frequency of the train can be finely tuned fully optically or electrically to provide a stable and efficient output signal modulation. Taking the polarization of the condensate into account, we elucidate the possibility of forming on-demand half-soliton trains.

Bohr-Sommerfeld quantization condition for Dirac states derived from an Ermakov-type invariant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thylwe, Karl-Erik; McCabe, Patrick

2013-05-15

It is shown that solutions of the second-order decoupled radial Dirac equations satisfy Ermakov-type invariants. These invariants lead to amplitude-phase-type representations of the radial spinor solutions, with exact relations between their amplitudes and phases. Implications leading to a Bohr-Sommerfeld quantization condition for bound states, and a few particular atomic/ionic and nuclear/hadronic bound-state situations are discussed.

Killing-Yano tensor and supersymmetry of the self-dual Plebański-Demiański solution

NASA Astrophysics Data System (ADS)

Nozawa, Masato; Houri, Tsuyoshi

2016-06-01

We explore various aspects of the self-dual Plebański-Demiański (PD) family in the Euclidean Einstein-Maxwell-Λ system. The Killing-Yano tensor which was recently found by Yasui and one of the present authors allows us to prove that the self-dual PD metric can be brought into the self-dual Carter metric by an orientation-reversing coordinate transformation. We show that the self-dual PD solution admits two independent Killing spinors in the framework of N = 2 minimal gauged supergravity, whereas the non-self-dual solution admits only a single Killing spinor. This can be demonstrated by casting the self-dual PD metric into two distinct Przanowski-Tod forms. As a by-product, a new example of the three-dimensional Einstein-Weyl space is presented. We also prove that the self-dual PD metric falls into two different Calderbank-Pedersen families, which are determined by a single function subjected to a linear equation on the two-dimensional hyperbolic space. Furthermore, we consider the hyper-Kähler case for which the metric falls into the Gibbons-Hawking class. We find that the condition for the nonexistence of the Dirac-Misner string enforces the solution with a nonvanishing acceleration parameter to the Eguchi-Hanson space.

Superfluidity and spin superfluidity in spinor Bose gases

NASA Astrophysics Data System (ADS)

Armaitis, J.; Duine, R. A.

2017-05-01

We show that spinor Bose gases subject to a quadratic Zeeman effect exhibit coexisting superfluidity and spin superfluidity, and study the interplay between these two distinct types of superfluidity. To illustrate that the basic principles governing these two types of superfluidity are the same, we describe the magnetization and particle-density dynamics in a single hydrodynamic framework. In this description spin and mass supercurrents are driven by their respective chemical potential gradients. As an application, we propose an experimentally accessible stationary state, where the two types of supercurrents counterflow and cancel each other, thus resulting in no mass transport. Furthermore, we propose a straightforward setup to probe spin superfluidity by measuring the in-plane magnetization angle of the whole cloud of atoms. We verify the robustness of these findings by evaluating the four-magnon collision time, and find that the time scale for coherent (superfluid) dynamics is separated from that of the slower incoherent dynamics by one order of magnitude. Comparing the atom and magnon kinetics reveals that while the former can be hydrodynamic, the latter is typically collisionless under most experimental conditions. This implies that, while our zero-temperature hydrodynamic equations are a valid description of spin transport in Bose gases, a hydrodynamic description that treats both mass and spin transport at finite temperatures may not be readily feasible.

Spin-orbit coupling calculations with the two-component normalized elimination of the small component method

NASA Astrophysics Data System (ADS)

Filatov, Michael; Zou, Wenli; Cremer, Dieter

2013-07-01

A new algorithm for the two-component Normalized Elimination of the Small Component (2cNESC) method is presented and tested in the calculation of spin-orbit (SO) splittings for a series of heavy atoms and their molecules. The 2cNESC is a Dirac-exact method that employs the exact two-component one-electron Hamiltonian and thus leads to exact Dirac SO splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000), 10.1103/PhysRevB.62.7809]. The use of the screened nucleus potential for the two-electron SO interaction leads to accurate spinor energy splittings, for which the deviations from the accurate Dirac Fock-Coulomb values are on the average far below the deviations observed for other effective one-electron SO operators. For hydrogen halides HX (X = F, Cl, Br, I, At, and Uus) and mercury dihalides HgX2 (X = F, Cl, Br, I) trends in spinor energies and SO splittings as obtained with the 2cNESC method are analyzed and discussed on the basis of coupling schemes and the electronegativity of X.

Quantum incommensurate skyrmion crystals and commensurate to in-commensurate transitions in cold atoms and materials with spin-orbit couplings in a Zeeman field

NASA Astrophysics Data System (ADS)

Sun, Fadi; Ye, Jinwu; Liu, Wu-Ming

2017-08-01

In this work, we study strongly interacting spinor atoms in a lattice subject to a two dimensional (2d) anisotropic Rashba type of spin orbital coupling (SOC) and an Zeeman field. We find the interplay between the Zeeman field and the SOC provides a new platform to host rich and novel classes of quantum commensurate and in-commensurate phases, excitations and phase transitions. These commensurate phases include two collinear states at low and high Zeeman field, two co-planar canted states at mirror reflected SOC parameters respectively. Most importantly, there are non-coplanar incommensurate Skyrmion (IC-SkX) crystal phases surrounded by the four commensurate phases. New excitation spectra above all the five phases, especially on the IC-SKX phase are computed. Three different classes of quantum commensurate to in-commensurate transitions from the IC-SKX to its four neighboring commensurate phases are identified. Finite temperature behaviors and transitions are discussed. The critical temperatures of all the phases can be raised above that reachable by current cold atom cooling techniques simply by tuning the number of atoms N per site. In view of recent impressive experimental advances in generating 2d SOC for cold atoms in optical lattices, these new many-body phenomena can be explored in the current and near future cold atom experiments. Applications to various materials such as MnSi, {Fe}}0.5 {Co}}0.5Si, especially the complex incommensurate magnetic ordering in Li2IrO3 are given.

Semiconductor spintronics: The full matrix approach

NASA Astrophysics Data System (ADS)

Rossani, A.

2015-12-01

A new model, based on an asymptotic procedure for solving the spinor kinetic equations of electrons and phonons is proposed, which gives naturally the displaced Fermi-Dirac distribution function at the leading order. The balance equations for the electron number, energy density and momentum, plus the Poisson’s equation, constitute now a system of six equations. Moreover, two equations for the evolution of the spin densities are added, which account for a general dispersion relation.

Pseudospin symmetry of the Dirac equation for a Möbius square plus Mie type potential with a Coulomb-like tensor interaction via SUSYQM

NASA Astrophysics Data System (ADS)

Akpan, N. Ikot; Zarrinkamar, S.; Eno, J. Ibanga; Maghsoodi, E.; Hassanabadi, H.

2014-01-01

We investigate the approximate solution of the Dirac equation for a combination of Möbius square and Mie type potentials under the pseudospin symmetry limit by using supersymmetry quantum mechanics. We obtain the bound-state energy equation and the corresponding spinor wave functions in an approximate analytical manner. We comment on the system via various useful figures and tables.

Gate-dependent Pseudospin Mixing in Graphene/boron Nitride Moire Superlattices

DTIC Science & Technology

2014-08-31

LETTERS PUBLISHED ONLINE: 31 AUGUST 2014 | DOI : 10.1038/NPHYS3075 Gate-dependent pseudospin mixing in graphene/boron nitride moiré superlattices... Dirac –Weyl spinors with a two-component pseudospin1–12. The unique pseudospin structure of Dirac electrons leads to emerging phenomena such as the...massless Dirac cone2, anomalous quantum Hall eect2,3, and Klein tunnelling4,5 in graphene. The capability to manipulate electron pseudospin is highly

Picard Trajectory Approximation Iteration for Efficient Orbit Propagation

DTIC Science & Technology

2015-07-21

Eqn (8)) for an iterative ap- proximation of eccentric anomaly, and is transformed back to . The Lambert/ Kepler time – eccentric anomaly relationship...of Kepler motion based on spinor regulari- zation, Journal fur die Reine und Angewandt Mathematik 218, 204-219, 1965. [3] Levi-Civita T., Sur la...transformed back to  , ,x y z . The Lambert/ Kepler time – eccentric anomaly relationship is iterated by a Newton/Secant method to converge on the

Introduction of a Classical Level in Quantum Theory

NASA Astrophysics Data System (ADS)

Prosperi, G. M.

2016-11-01

In an old paper of our group in Milano a formalism was introduced for the continuous monitoring of a system during a certain interval of time in the framework of a somewhat generalized approach to quantum mechanics (QM). The outcome was a distribution of probability on the space of all the possible continuous histories of a set of quantities to be considered as a kind of coarse grained approximation to some ordinary quantum observables commuting or not. In fact the main aim was the introduction of a classical level in the context of QM, treating formally a set of basic quantities, to be considered as beables in the sense of Bell, as continuously taken under observation. However the effect of such assumption was a permanent modification of the Liouville-von Neumann equation for the statistical operator by the introduction of a dissipative term which is in conflict with basic conservation rules in all reasonable models we had considered. Difficulties were even encountered for a relativistic extension of the formalism. In this paper I propose a modified version of the original formalism which seems to overcome both difficulties. First I study the simple models of an harmonic oscillator and a free scalar field in which a coarse grain position and a coarse grained field respectively are treated as beables. Then I consider the more realistic case of spinor electrodynamics in which only certain coarse grained electric and magnetic fields are introduced as classical variables and no matter related quantities.

Type IIB flux vacua from G-theory II

NASA Astrophysics Data System (ADS)

Candelas, Philip; Constantin, Andrei; Damian, Cesar; Larfors, Magdalena; Morales, Jose Francisco

2015-02-01

We find analytic solutions of type IIB supergravity on geometries that locally take the form Mink × M 4 × ℂ with M 4 a generalised complex manifold. The solutions involve the metric, the dilaton, NSNS and RR flux potentials (oriented along the M 4) parametrised by functions varying only over ℂ. Under this assumption, the supersymmetry equations are solved using the formalism of pure spinors in terms of a finite number of holomorphic functions. Alternatively, the solutions can be viewed as vacua of maximally supersymmetric supergravity in six dimensions with a set of scalar fields varying holomorphically over ℂ. For a class of solutions characterised by up to five holomorphic functions, we outline how the local solutions can be completed to four-dimensional flux vacua of type IIB theory. A detailed study of this global completion for solutions with two holomorphic functions has been carried out in the companion paper [1]. The fluxes of the global solutions are, as in F-theory, entirely codified in the geometry of an auxiliary K3 fibration over ℂℙ1. The results provide a geometric construction of fluxes in F-theory.

Foundations of Space and Time

NASA Astrophysics Data System (ADS)

Murugan, Jeff; Weltman, Amanda; Ellis, George F. R.

2012-07-01

1. The problem with quantum gravity Jeff Murugan, Amanda Weltman and George F. R. Eliis; 2. A dialogue on the nature of gravity Thanu Padmanabhan; 3. Effective theories and modifications of gravity Cliff Burgess; 4. The small scale structure of spacetime Steve Carlip; 5. Ultraviolet divergences in supersymmetric theories Kellog Stelle; 6. Cosmological quantum billiards Axel Kleinschmidt and Hermann Nicolai; 7. Progress in RNS string theory and pure spinors Dimitri Polyakov; 8. Recent trends in superstring phenomenology Massimo Bianchi; 9. Emergent spacetime Robert de Mello Koch and Jeff Murugan; 10. Loop quantum gravity Hanno Sahlmann; 11. Loop quantum gravity and cosmology Martin Bojowald; 12. The microscopic dynamics of quantum space as a group field theory Daniele Oriti; 13. Causal dynamical triangulations and the quest for quantum gravity Jan Ambjørn, J. Jurkiewicz and Renate Loll; 14. Proper time is stochastic time in 2D quantum gravity Jan Ambjorn, Renate Loll, Y. Watabiki, W. Westra and S. Zohren; 15. Logic is to the quantum as geometry is to gravity Rafael Sorkin; 16. Causal sets: discreteness without symmetry breaking Joe Henson; 17. The Big Bang, quantum gravity, and black-hole information loss Roger Penrose; Index.

NASA Tech Briefs, April 2007

NASA Technical Reports Server (NTRS)

2007-01-01

Topics include: Wearable Environmental and Physiological Sensing Unit; Broadband Phase Retrieval for Image-Based Wavefront Sensing; Filter Function for Wavefront Sensing Over a Field of View; Iterative-Transform Phase Retrieval Using Adaptive Diversity; Wavefront Sensing With Switched Lenses for Defocus Diversity; Smooth Phase Interpolated Keying; Maintaining Stability During a Conducted-Ripple EMC Test; Photodiode Preamplifier for Laser Ranging With Weak Signals; Advanced High-Definition Video Cameras; Circuit for Full Charging of Series Lithium-Ion Cells; Analog Nonvolatile Computer Memory Circuits; JavaGenes Molecular Evolution; World Wind 3D Earth Viewing; Lithium Dinitramide as an Additive in Lithium Power Cells; Accounting for Uncertainties in Strengths of SiC MEMS Parts; Ion-Conducting Organic/Inorganic Polymers; MoO3 Cathodes for High-Temperature Lithium Thin-Film Cells; Counterrotating-Shoulder Mechanism for Friction Stir Welding; Strain Gauges Indicate Differential-CTE-Induced Failures; Antibodies Against Three Forms of Urokinase; Understanding and Counteracting Fatigue in Flight Crews; Active Correction of Aberrations of Low-Quality Telescope Optics; Dual-Beam Atom Laser Driven by Spinor Dynamics; Rugged, Tunable Extended-Cavity Diode Laser; Balloon for Long-Duration, High-Altitude Flight at Venus; and Wide-Temperature-Range Integrated Operational Amplifier.

An Electron is the God Particle

NASA Astrophysics Data System (ADS)

Wolff, Milo

2001-04-01

Philosophers, Clifford, Mach, Einstein, Wyle, Dirac & Schroedinger, believed that only a wave structure of particles could satisfy experiment and fulfill reality. A quantum Wave Structure of Matter is described here. It predicts the natural laws more accurately and completely than classic laws. Einstein reasoned that the universe depends on particles which are "spherically, spatially extended in space." and "Hence a discrete material particle has no place as a fundamental concept in a field theory." Thus the discrete point particle was wrong. He deduced the true electron is primal because its force range is infinite. Now, it is found the electron's wave structure contains the laws of Nature that rule the universe. The electron plays the role of creator - the God particle. Electron structure is a pair of spherical outward/inward quantum waves, convergent to a center in 3D space. This wave pair creates a h/4pi quantum spin when the in-wave spherically rotates to become the out-wave. Both waves form a spinor satisfying the Dirac Equation. Thus, the universe is binary like a computer. Reference: http://members.tripod.com/mwolff

Topological interface physics in spinor Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Borgh, Magnus; Ruostekoski, Janne

2013-05-01

We present an experimentally viable scheme whereby the physics of coherent interfaces between topologically distinct regions can be studied in an atomic quantum gas. The interface engineering is achieved using the internal spin structures of atoms together with local control over interaction strengths. We consider a coherent interface between polar and ferromagnetic regions of a spin-1 Bose-Einstein condensate and show that defects representing different topologies can connect continuously across the boundary. We show that energy minimization leads to nontrivial interface-crossing defect structures, demonstrating how the method can be used to study stability properties of field-theoretical solitons. We demonstrate, e.g., the formation of a half-quantum vortex arch, an Alice arch, on the interface, exhibiting the topological charge of a point defect. We also demonstrate an energetically stable connection of a coreless vortex to two half-quantum vortices. Our method can be extended to study interface physics in spin-2 and spin-3 BECs with richer phenomenology, or in strongly correlated optical-lattice systems. We acknowledge financial support from the Leverhulme Trust.

Continuous Faraday measurement of spin precession without light shifts

NASA Astrophysics Data System (ADS)

Jasperse, M.; Kewming, M. Â. J.; Fischer, S. Â. N.; Pakkiam, P.; Anderson, R. Â. P.; Turner, L. Â. D.

2017-12-01

We describe a dispersive Faraday optical probe of atomic spin which performs a weak measurement of spin projection of a quantum gas continuously for more than one second. To date, focusing bright far-off-resonance probes onto quantum gases has proved invasive due to strong scalar and vector light shifts exerting dipole and Stern-Gerlach forces. We show that tuning the probe near the magic-zero wavelength at 790 nm between the fine-structure doublet of 87Rb cancels the scalar light shift, and careful control of polarization eliminates the vector light shift. Faraday rotations due to each fine-structure line reinforce at this wavelength, enhancing the signal-to-noise ratio for a fixed rate of probe-induced decoherence. Using this minimally invasive spin probe, we perform microscale atomic magnetometry at high temporal resolution. Spectrogram analysis of the Larmor precession signal of a single spinor Bose-Einstein condensate measures a time-varying magnetic field strength with 1 μ G accuracy every 5 ms; or, equivalently, makes more than 200 successive measurements each at 10 pT /√{Hz } sensitivity.

Symmetry enhancement of extremal horizons in D  =  5 supergravity

NASA Astrophysics Data System (ADS)

Kayani, U.

2018-06-01

We consider the near-horizon geometry of supersymmetric extremal black holes in un-gauged and gauged 5-dimensional supergravity, coupled to abelian vector multiplets. By analyzing the global properties of the Killing spinors, we prove that the near-horizon geometries undergo a supersymmetry enhancement. This follows from a set of generalized Lichnerowicz-type theorems we establish, together with an index theory argument. As a consequence, these solutions always admit a symmetry group.

Causal localizations in relativistic quantum mechanics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Castrigiano, Domenico P. L., E-mail: castrig@ma.tum.de; Leiseifer, Andreas D., E-mail: andreas.leiseifer@tum.de

2015-07-15

Causal localizations describe the position of quantum systems moving not faster than light. They are constructed for the systems with finite spinor dimension. At the center of interest are the massive relativistic systems. For every positive mass, there is the sequence of Dirac tensor-localizations, which provides a complete set of inequivalent irreducible causal localizations. They obey the principle of special relativity and are fully Poincaré covariant. The boosters are determined by the causal position operator and the other Poincaré generators. The localization with minimal spinor dimension is the Dirac localization. Thus, the Dirac equation is derived here as a meremore » consequence of the principle of causality. Moreover, the higher tensor-localizations, not known so far, follow from Dirac’s localization by a simple construction. The probability of localization for positive energy states results to be described by causal positive operator valued (PO-) localizations, which are the traces of the causal localizations on the subspaces of positive energy. These causal Poincaré covariant PO-localizations for every irreducible massive relativistic system were, all the more, not known before. They are shown to be separated. Hence, the positive energy systems can be localized within every open region by a suitable preparation as accurately as desired. Finally, the attempt is made to provide an interpretation of the PO-localization operators within the frame of conventional quantum mechanics attributing an important role to the negative energy states.« less

Vortex and half-vortex dynamics in a nonlinear spinor quantum fluid

PubMed Central

Dominici, Lorenzo; Dagvadorj, Galbadrakh; Fellows, Jonathan M.; Ballarini, Dario; De Giorgi, Milena; Marchetti, Francesca M.; Piccirillo, Bruno; Marrucci, Lorenzo; Bramati, Alberto; Gigli, Giuseppe; Szymańska, Marzena H.; Sanvitto, Daniele

2015-01-01

Vortices are archetypal objects that recur in the universe across the scale of complexity, from subatomic particles to galaxies and black holes. Their appearance is connected with spontaneous symmetry breaking and phase transitions. In Bose-Einstein condensates and superfluids, vortices are both point-like and quantized quasiparticles. We use a two-dimensional (2D) fluid of polaritons, bosonic particles constituted by hybrid photonic and electronic oscillations, to study quantum vortex dynamics. Polaritons benefit from easiness of wave function phase detection, a spinor nature sustaining half-integer vorticity, strong nonlinearity, and tuning of the background disorder. We can directly generate by resonant pulsed excitations a polariton condensate carrying either a full or half-integer vortex as initial condition and follow their coherent evolution using ultrafast imaging on the picosecond scale. The observations highlight a rich phenomenology, such as the spiraling of the half-vortex and the joint path of the twin charges of a full vortex, until the moment of their splitting. Furthermore, we observe the ordered branching into newly generated secondary couples, associated with the breaking of radial and azimuthal symmetries. This allows us to devise the interplay of nonlinearity and sample disorder in shaping the fluid and driving the vortex dynamics. In addition, our observations suggest that phase singularities may be seen as fundamental particles whose quantized events span from pair creation and recombination to 2D+t topological vortex strings. PMID:26665174

FormTracer. A mathematica tracing package using FORM

NASA Astrophysics Data System (ADS)

Cyrol, Anton K.; Mitter, Mario; Strodthoff, Nils

2017-10-01

We present FormTracer, a high-performance, general purpose, easy-to-use Mathematica tracing package which uses FORM. It supports arbitrary space and spinor dimensions as well as an arbitrary number of simple compact Lie groups. While keeping the usability of the Mathematica interface, it relies on the efficiency of FORM. An additional performance gain is achieved by a decomposition algorithm that avoids redundant traces in the product tensors spaces. FormTracer supports a wide range of syntaxes which endows it with a high flexibility. Mathematica notebooks that automatically install the package and guide the user through performing standard traces in space-time, spinor and gauge-group spaces are provided. Program Files doi:http://dx.doi.org/10.17632/7rd29h4p3m.1 Licensing provisions: GPLv3 Programming language: Mathematica and FORM Nature of problem: Efficiently compute traces of large expressions Solution method: The expression to be traced is decomposed into its subspaces by a recursive Mathematica expansion algorithm. The result is subsequently translated to a FORM script that takes the traces. After FORM is executed, the final result is either imported into Mathematica or exported as optimized C/C++/Fortran code. Unusual features: The outstanding features of FormTracer are the simple interface, the capability to efficiently handle an arbitrary number of Lie groups in addition to Dirac and Lorentz tensors, and a customizable input-syntax.

Causal localizations in relativistic quantum mechanics

NASA Astrophysics Data System (ADS)

Castrigiano, Domenico P. L.; Leiseifer, Andreas D.

2015-07-01

Causal localizations describe the position of quantum systems moving not faster than light. They are constructed for the systems with finite spinor dimension. At the center of interest are the massive relativistic systems. For every positive mass, there is the sequence of Dirac tensor-localizations, which provides a complete set of inequivalent irreducible causal localizations. They obey the principle of special relativity and are fully Poincaré covariant. The boosters are determined by the causal position operator and the other Poincaré generators. The localization with minimal spinor dimension is the Dirac localization. Thus, the Dirac equation is derived here as a mere consequence of the principle of causality. Moreover, the higher tensor-localizations, not known so far, follow from Dirac's localization by a simple construction. The probability of localization for positive energy states results to be described by causal positive operator valued (PO-) localizations, which are the traces of the causal localizations on the subspaces of positive energy. These causal Poincaré covariant PO-localizations for every irreducible massive relativistic system were, all the more, not known before. They are shown to be separated. Hence, the positive energy systems can be localized within every open region by a suitable preparation as accurately as desired. Finally, the attempt is made to provide an interpretation of the PO-localization operators within the frame of conventional quantum mechanics attributing an important role to the negative energy states.

Vortex and half-vortex dynamics in a nonlinear spinor quantum fluid.

PubMed

Dominici, Lorenzo; Dagvadorj, Galbadrakh; Fellows, Jonathan M; Ballarini, Dario; De Giorgi, Milena; Marchetti, Francesca M; Piccirillo, Bruno; Marrucci, Lorenzo; Bramati, Alberto; Gigli, Giuseppe; Szymańska, Marzena H; Sanvitto, Daniele

2015-12-01

Vortices are archetypal objects that recur in the universe across the scale of complexity, from subatomic particles to galaxies and black holes. Their appearance is connected with spontaneous symmetry breaking and phase transitions. In Bose-Einstein condensates and superfluids, vortices are both point-like and quantized quasiparticles. We use a two-dimensional (2D) fluid of polaritons, bosonic particles constituted by hybrid photonic and electronic oscillations, to study quantum vortex dynamics. Polaritons benefit from easiness of wave function phase detection, a spinor nature sustaining half-integer vorticity, strong nonlinearity, and tuning of the background disorder. We can directly generate by resonant pulsed excitations a polariton condensate carrying either a full or half-integer vortex as initial condition and follow their coherent evolution using ultrafast imaging on the picosecond scale. The observations highlight a rich phenomenology, such as the spiraling of the half-vortex and the joint path of the twin charges of a full vortex, until the moment of their splitting. Furthermore, we observe the ordered branching into newly generated secondary couples, associated with the breaking of radial and azimuthal symmetries. This allows us to devise the interplay of nonlinearity and sample disorder in shaping the fluid and driving the vortex dynamics. In addition, our observations suggest that phase singularities may be seen as fundamental particles whose quantized events span from pair creation and recombination to 2D+t topological vortex strings.

General structure of fermion two-point function and its spectral representation in a hot magnetized medium

NASA Astrophysics Data System (ADS)

Das, Aritra; Bandyopadhyay, Aritra; Roy, Pradip K.; Mustafa, Munshi G.

2018-02-01

We have systematically constructed the general structure of the fermion self-energy and the effective quark propagator in the presence of a nontrivial background such as a hot magnetized medium. This is applicable to both QED and QCD. The hard thermal loop approximation has been used for the heat bath. We have also examined transformation properties of the effective fermion propagator under some of the discrete symmetries of the system. Using the effective fermion propagator we have analyzed the fermion dispersion spectra in a hot magnetized medium along with the spinor for each fermion mode obtained by solving the modified Dirac equation. The fermion spectra is found to reflect the discrete symmetries of the two-point functions. We note that for a chirally symmetric theory the degenerate left- and right-handed chiral modes in vacuum or in a heat bath get separated and become asymmetric in the presence of a magnetic field without disturbing the chiral invariance. The obtained general structure of the two-point functions is verified by computing the three-point function, which agrees with the existing results in one-loop order. Finally, we have computed explicitly the spectral representation of the two-point functions which would be very important to study the spectral properties of the hot magnetized medium corresponding to QED and QCD with background magnetic field.

Competition between Bose-Einstein Condensation and Spin Dynamics.

PubMed

Naylor, B; Brewczyk, M; Gajda, M; Gorceix, O; Maréchal, E; Vernac, L; Laburthe-Tolra, B

2016-10-28

We study the impact of spin-exchange collisions on the dynamics of Bose-Einstein condensation by rapidly cooling a chromium multicomponent Bose gas. Despite relatively strong spin-dependent interactions, the critical temperature for Bose-Einstein condensation is reached before the spin degrees of freedom fully thermalize. The increase in density due to Bose-Einstein condensation then triggers spin dynamics, hampering the formation of condensates in spin-excited states. Small metastable spinor condensates are, nevertheless, produced, and they manifest in strong spin fluctuations.

Decomposition of the polynomial kernel of arbitrary higher spin Dirac operators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eelbode, D., E-mail: David.Eelbode@ua.ac.be; Raeymaekers, T., E-mail: Tim.Raeymaekers@UGent.be; Van der Jeugt, J., E-mail: Joris.VanderJeugt@UGent.be

2015-10-15

In a series of recent papers, we have introduced higher spin Dirac operators, which are generalisations of the classical Dirac operator. Whereas the latter acts on spinor-valued functions, the former acts on functions taking values in arbitrary irreducible half-integer highest weight representations for the spin group. In this paper, we describe how the polynomial kernel spaces of such operators decompose in irreducible representations of the spin group. We will hereby make use of results from representation theory.

Bright solitons in non-equilibrium coherent quantum matter

PubMed Central

Pinsker, F.; Flayac, H.

2016-01-01

We theoretically demonstrate a mechanism for bright soliton generation in spinor non-equilibrium Bose–Einstein condensates made of atoms or quasi-particles such as polaritons in semiconductor microcavities. We give analytical expressions for bright (half) solitons as minimizing functions of a generalized non-conservative Lagrangian elucidating the unique features of inter and intra-competition in non-equilibrium systems. The analytical results are supported by a detailed numerical analysis that further shows the rich soliton dynamics inferred by their instability and mutual cross-interactions. PMID:26997892

Stability Analysis of Finite Difference Approximations to Hyperbolic Systems,and Problems in Applied and Computational Matrix and Operator Theory

DTIC Science & Technology

1990-12-07

Fundaqao Calouste Gulbenkian, Instituto Gulbenkian de Ci~ncia, Centro de C6lculo Cientifico , Coimbra, 1973. 28, Dirac, P. A. M., Spinors in Hilbert Space...Office of Scientific Research grants 1965 Mathematical Association of America Editorial Prize for the article entitled: "Linear Transformations on...matrices" 1966 L.R. Ford Memorial Prize awarded by the Mathematical Association of America for the article , "Permanents" 1989 Outstanding Computer

Quantum dynamics of relativistic bosons through nonminimal vector square potentials

NASA Astrophysics Data System (ADS)

de Oliveira, Luiz P.

2016-09-01

The dynamics of relativistic bosons (scalar and vectorial) through nonminimal vector square (well and barrier) potentials is studied in the Duffin-Kemmer-Petiau (DKP) formalism. We show that the problem can be mapped in effective Schrödinger equations for a component of the DKP spinor. An oscillatory transmission coefficient is found and there is total reflection. Additionally, the energy spectrum of bound states is obtained and reveals the Schiff-Snyder-Weinberg effect, for specific conditions the potential lodges bound states of particles and antiparticles.

SL(2,C) gravity on noncommutative space with Poisson structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miao Yangang; Zhang Shaojun

2010-10-15

The Einstein's gravity theory can be formulated as an SL(2,C) gauge theory in terms of spinor notations. In this paper, we consider a noncommutative space with the Poisson structure and construct an SL(2,C) formulation of gravity on such a space. Using the covariant coordinate technique, we build a gauge invariant action in which, according to the Seiberg-Witten map, the physical degrees of freedom are expressed in terms of their commutative counterparts up to the first order in noncommutative parameters.

On supersymmetric anti-de Sitter, de Sitter and Minkowski flux backgrounds

NASA Astrophysics Data System (ADS)

Gran, U.; Gutowski, J. B.; Papadopoulos, G.

2018-03-01

We test the robustness of the conditions required for the existence of (supersymmetric) warped flux anti-de Sitter, de Sitter, and Minkowski backgrounds in supergravity theories using as examples suitable foliations of anti-de Sitter spaces. We find that there are supersymmetric de Sitter solutions in supergravity theories including maximally supersymmetric ones in 10- and 11-dimensional supergravities. Moreover, warped flux Minkowski backgrounds can admit Killing spinors which are not Killing on the Minkowski subspace and therefore cannot be put in a factorized form.

Parity violation and the masslessness of the neutrino

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mannheim, P.D.

1978-09-01

It is proposed that the weak interaction be obtained by gauging the strong interaction chiral flavor group. The neutrinos are then four-component spinors. Pairs of right-handed neutrinos are allowed to condense into the vacuum. This produces maximal parity violation in both the quark and lepton sectors of the weak interaction, keeps the neutrinos massless, and also leads to the conventional Weinberg mixing pattern. The approach also in principle provides a way of calculating the Cabibbo angle. 11 references.

Unified space--time trigonometry and its applications to relativistic kinematics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaccarini, A.

1973-06-15

A geometrical approach to relativistic kinematics is presented. Owing to a unified space-time trigonometry, the spherical trigonometry formalism may be used to describe and study the kinematics of any collision process. Lorentz transformations may thus lie treated as purely geometrical problems. A different way to define a unified trigonometry is also proposed, which is based on the spinor representation of the Lorentz group. This leads to a different and more general formalism than the former one. (auth)

Perspectives of Light-Front Quantized Field Theory: Some New Results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Srivastava, Prem P.

1999-08-13

A review of some basic topics in the light-front (LF) quantization of relativistic field theory is made. It is argued that the LF quantization is equally appropriate as the conventional one and that they lead, assuming the microcausality principle, to the same physical content. This is confirmed in the studies on the LF of the spontaneous symmetry breaking (SSB), of the degenerate vacua in Schwinger model (SM) and Chiral SM (CSM), of the chiral boson theory, and of the QCD in covariant gauges among others. The discussion on the LF is more economical and more transparent than that found inmore » the conventional equal-time quantized theory. The removal of the constraints on the LF phase space by following the Dirac method, in fact, results in a substantially reduced number of independent dynamical variables. Consequently, the descriptions of the physical Hilbert space and the vacuum structure, for example, become more tractable. In the context of the Dyson-Wick perturbation theory the relevant propagators in the front form theory are causal. The Wick rotation can then be performed to employ the Euclidean space integrals in momentum space. The lack of manifest covariance becomes tractable, and still more so if we employ, as discussed in the text, the Fourier transform of the fermionic field based on a special construction of the LF spinor. The fact that the hyperplanes x{sup {+-}} = 0 constitute characteristic surfaces of the hyperbolic partial differential equation is found irrelevant in the quantized theory; it seems sufficient to quantize the theory on one of the characteristic hyperplanes.« less

Cartan gravity, matter fields, and the gauge principle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Westman, Hans F., E-mail: hwestman74@gmail.com; Zlosnik, Tom G., E-mail: t.zlosnik@imperial.ac.uk

Gravity is commonly thought of as one of the four force fields in nature. However, in standard formulations its mathematical structure is rather different from the Yang–Mills fields of particle physics that govern the electromagnetic, weak, and strong interactions. This paper explores this dissonance with particular focus on how gravity couples to matter from the perspective of the Cartan-geometric formulation of gravity. There the gravitational field is represented by a pair of variables: (1) a ‘contact vector’ V{sup A} which is geometrically visualized as the contact point between the spacetime manifold and a model spacetime being ‘rolled’ on top ofmore » it, and (2) a gauge connection A{sub μ}{sup AB}, here taken to be valued in the Lie algebra of SO(2,3) or SO(1,4), which mathematically determines how much the model spacetime is rotated when rolled. By insisting on two principles, the gauge principle and polynomial simplicity, we shall show how one can reformulate matter field actions in a way that is harmonious with Cartan’s geometric construction. This yields a formulation of all matter fields in terms of first order partial differential equations. We show in detail how the standard second order formulation can be recovered. In particular, the Hodge dual, which characterizes the structure of bosonic field equations, pops up automatically. Furthermore, the energy–momentum and spin-density three-forms are naturally combined into a single object here denoted the spin-energy–momentum three-form. Finally, we highlight a peculiarity in the mathematical structure of our first-order formulation of Yang–Mills fields. This suggests a way to unify a U(1) gauge field with gravity into a SO(1,5)-valued gauge field using a natural generalization of Cartan geometry in which the larger symmetry group is spontaneously broken down to SO(1,3)×U(1). The coupling of this unified theory to matter fields and possible extensions to non-Abelian gauge fields are left as open questions. -- Highlights: •Develops Cartan gravity to include matter fields. •Coupling to gravity is done using the standard gauge prescription. •Matter actions are manifestly polynomial in all field variables. •Standard equations recovered on-shell for scalar, spinor and Yang–Mills fields. •Unification of a U(1) field with gravity based on the orthogonal group SO(1,5)« less

Dual-Beam Atom Laser Driven by Spinor Dynamics

NASA Technical Reports Server (NTRS)

Thompson, Robert; Lundblad, Nathan; Maleki, Lute; Aveline, David

2007-01-01

An atom laser now undergoing development simultaneously generates two pulsed beams of correlated Rb-87 atoms. (An atom laser is a source of atoms in beams characterized by coherent matter waves, analogous to a conventional laser, which is a source of coherent light waves.) The pumping mechanism of this atom laser is based on spinor dynamics in a Bose-Einstein condensate. By virtue of the angular-momentum conserving collisions that generate the two beams, the number of atoms in one beam is correlated with the number of atoms in the other beam. Such correlations are intimately linked to entanglement and squeezing in atomic ensembles, and atom lasers like this one could be used in exploring related aspects of Bose-Einstein condensates, and as components of future sensors relying on atom interferometry. In this atom-laser apparatus, a Bose-Einstein condensate of about 2 x 10(exp 6) Rb-87 atoms at a temperature of about 120 micro-K is first formed through all-optical means in a relatively weak singlebeam running-wave dipole trap that has been formed by focusing of a CO2-laser beam. By a technique that is established in the art, the trap is loaded from an ultrahigh-vacuum magnetooptical trap that is, itself, loaded via a cold atomic beam from an upstream two-dimensional magneto-optical trap that resides in a rubidium-vapor cell that is differentially pumped from an adjoining vacuum chamber, wherein are performed scientific observations of the beams ultimately generated by the atom laser.

Second-order differential equations for bosons with spin j ≥ 1 and in the bases of general tensor-spinors of rank 2j

NASA Astrophysics Data System (ADS)

Banda Guzmán, V. M.; Kirchbach, M.

2016-09-01

A boson of spin j≥ 1 can be described in one of the possibilities within the Bargmann-Wigner framework by means of one sole differential equation of order twice the spin, which however is known to be inconsistent as it allows for non-local, ghost and acausally propagating solutions, all problems which are difficult to tackle. The other possibility is provided by the Fierz-Pauli framework which is based on the more comfortable to deal with second-order Klein-Gordon equation, but it needs to be supplemented by an auxiliary condition. Although the latter formalism avoids some of the pathologies of the high-order equations, it still remains plagued by some inconsistencies such as the acausal propagation of the wave fronts of the (classical) solutions within an electromagnetic environment. We here suggest a method alternative to the above two that combines their advantages while avoiding the related difficulties. Namely, we suggest one sole strictly D^{(j,0)oplus (0,j)} representation specific second-order differential equation, which is derivable from a Lagrangian and whose solutions do not violate causality. The equation under discussion presents itself as the product of the Klein-Gordon operator with a momentum-independent projector on Lorentz irreducible representation spaces constructed from one of the Casimir invariants of the spin-Lorentz group. The basis used is that of general tensor-spinors of rank 2 j.

More on the hidden symmetries of 11D supergravity

NASA Astrophysics Data System (ADS)

Andrianopoli, Laura; D'Auria, Riccardo; Ravera, Lucrezia

2017-09-01

In this paper we clarify the relations occurring among the osp (1 | 32) algebra, the M-algebra and the hidden superalgebra underlying the Free Differential Algebra of D=11 supergravity (to which we will refer as DF-algebra) that was introduced in the literature by D'Auria and Frè in 1981 and is actually a (Lorentz valued) central extension of the M-algebra including a nilpotent spinor generator, Q‧. We focus in particular on the 4-form cohomology in 11D superspace of the supergravity theory, strictly related to the presence in the theory of a 3-form A (3). Once formulated in terms of its hidden superalgebra of 1-forms, we find that A (3) can be decomposed into the sum of two parts having different group-theoretical meaning: One of them allows to reproduce the FDA of the 11D Supergravity due to non-trivial contributions to the 4-form cohomology in superspace, while the second one does not contribute to the 4-form cohomology, being a closed 3-form in the vacuum, defining however a one parameter family of trilinear forms invariant under a symmetry algebra related to osp (1 | 32) by redefining the spin connection and adding a new Maurer-Cartan equation. We further discuss about the crucial role played by the 1-form spinor η (dual to the nilpotent generator Q‧) for the 4-form cohomology of the eleven dimensional theory on superspace.

A simple scheme for magnetic balance in four-component relativistic Kohn-Sham calculations of nuclear magnetic resonance shielding constants in a Gaussian basis.

PubMed

Olejniczak, Małgorzata; Bast, Radovan; Saue, Trond; Pecul, Magdalena

2012-01-07

We report the implementation of nuclear magnetic resonance (NMR) shielding tensors within the four-component relativistic Kohn-Sham density functional theory including non-collinear spin magnetization and employing London atomic orbitals to ensure gauge origin independent results, together with a new and efficient scheme for assuring correct balance between the large and small components of a molecular four-component spinor in the presence of an external magnetic field (simple magnetic balance). To test our formalism we have carried out calculations of NMR shielding tensors for the HX series (X = F, Cl, Br, I, At), the Xe atom, and the Xe dimer. The advantage of simple magnetic balance scheme combined with the use of London atomic orbitals is the fast convergence of results (when compared with restricted kinetic balance) and elimination of linear dependencies in the basis set (when compared to unrestricted kinetic balance). The effect of including spin magnetization in the description of NMR shielding tensor has been found important for hydrogen atoms in heavy HX molecules, causing an increase of isotropic values of 10%, but negligible for heavy atoms.

Malleability and optimization of tetrahedral metamorphic element for deployable truss antenna reflector

NASA Astrophysics Data System (ADS)

Hu, Fei; Song, Yanping; Huang, Zhirong; Liu, Wenlan; Li, Wan

2018-05-01

The tetrahedral elements that make up the large deployable reflector (LDR) are a kind of metamorphic element, which belongs to the multi-loop coupling mechanism. Firstly, the method of combining topology with screw theory is put forward. The parametric model and the constrained matrix are established to analyze the malleability of 3RR-3RRR tetrahedral element. Secondly, the kinematics expression of each motion pair is deduced by the relationship between the velocity and the motion spinor. Finally, the configuration of the metamorphic element is optimized to make the parabolic antenna fully folded, so that the antenna can meet the maximum folding ratio. The results show that the 3RR-3RRR element is a single-degree of freedom (DOF) mechanism. What's more, three new configurations 3RS-3RRR, 3SR-3RRR and 3UU-3RRR are obtained on the basis of optimization. In particular, it proves to be that the LDR which consists of the 3RS-3RRR metamorphic element can achieve the maximum folding ratio. This paper provides a theoretical basis for the computer-aided design of the truss antennas, which has an excellent applicability in the field of aerospace and other multi-loop coupling mechanism.

General N=1 supersymmetric flux vacua of massive type IIA string theory.

PubMed

Behrndt, Klaus; Cvetic, Mirjam

2005-07-08

We derive conditions for the existence of four-dimensional N=1 supersymmetric flux vacua of massive type IIA string theory with general supergravity fluxes turned on. For an SU(3) singlet Killing spinor, we show that such flux vacua exist when the internal geometry is nearly Kähler. The geometry is not warped, all the allowed fluxes are proportional to the mass parameter, and the dilaton is fixed by a ratio of (quantized) fluxes. The four-dimensional cosmological constant, while negative, becomes small in the vacuum with the weak string coupling.

Pseudospin symmetry for modified Rosen-Morse potential including a Pekeris-type approximation to the pseudo-centrifugal term

NASA Astrophysics Data System (ADS)

Wei, Gao-Feng; Dong, Shi-Hai

2010-11-01

By applying a Pekeris-type approximation to the pseudo-centrifugal term, we study the pseudospin symmetry of a Dirac nucleon subjected to scalar and vector modified Rosen-Morse (MRM) potentials. A complicated quartic energy equation and spinor wave functions with arbitrary spin-orbit coupling quantum number k are presented. The pseudospin degeneracy is checked numerically. Pseudospin symmetry is discussed theoretically and numerically in the limit case α rightarrow 0 . It is found that the relativistic MRM potential cannot trap a Dirac nucleon in this limit.

Spin Order and Phase Transitions in Chains of Polariton Condensates.

PubMed

Ohadi, H; Ramsay, A J; Sigurdsson, H; Del Valle-Inclan Redondo, Y; Tsintzos, S I; Hatzopoulos, Z; Liew, T C H; Shelykh, I A; Rubo, Y G; Savvidis, P G; Baumberg, J J

2017-08-11

We demonstrate that multiply coupled spinor polariton condensates can be optically tuned through a sequence of spin-ordered phases by changing the coupling strength between nearest neighbors. For closed four-condensate chains these phases span from ferromagnetic (FM) to antiferromagnetic (AFM), separated by an unexpected crossover phase. This crossover phase is composed of alternating FM-AFM bonds. For larger eight-condensate chains, we show the critical role of spatial inhomogeneities and demonstrate a scheme to overcome them and prepare any desired spin state. Our observations thus demonstrate a fully controllable nonequilibrium spin lattice.

Group theoretical approach to the Dirac operator on S 2

NASA Astrophysics Data System (ADS)

Gutiérrez, Sergio; Huet, Idrish

2018-04-01

In this revision we outline the group theoretical approach to formulate and solve the eigenvalue problem of the Dirac operator on the round 2-sphere conceived as the right coset S 2 = SU(2)/U(1). Starting from general symmetry considerations we illustrate the formulation of the Dirac operator through left action or right action differential operators, whose properties on a right coset are quite different. The construction of the spinor space and the solution of the spectral problem using group theoretical methods is also presented.

Particle-like solutions of the Einstein-Dirac-Maxwell equations

NASA Astrophysics Data System (ADS)

Finster, Felix; Smoller, Joel; Yau, Shing-Tung

1999-08-01

We consider the coupled Einstein-Dirac-Maxwell equations for a static, spherically symmetric system of two fermions in a singlet spinor state. Soliton-like solutions are constructed numerically. The stability and the properties of the ground state solutions are discussed for different values of the electromagnetic coupling constant. We find solutions even when the electromagnetic coupling is so strong that the total interaction is repulsive in the Newtonian limit. Our solutions are regular and well-behaved; this shows that the combined electromagnetic and gravitational self-interaction of the Dirac particles is finite.

Spins and parities of the odd-A P isotopes within a relativistic mean-field model and elastic magnetic electron-scattering theory

NASA Astrophysics Data System (ADS)

Wang, Zaijun; Ren, Zhongzhou; Dong, Tiekuang; Xu, Chang

2014-08-01

The ground-state spins and parities of the odd-A phosphorus isotopes 25-47P are studied with the relativistic mean-field (RMF) model and relativistic elastic magnetic electron-scattering theory (REMES). Results of the RMF model with the NL-SH, TM2, and NL3 parameters show that the 2s1/2 and 1d3/2 proton level inversion may occur for the neutron-rich isotopes 37-47P, and, consequently, the possible spin-parity values of 37-47P may be 3/2+, which, except for P47, differs from those given by the NUBASE2012 nuclear data table by Audi et al. Calculations of the elastic magnetic electron scattering of 37-47P with the single valence proton in the 2s1/2 and 1d3/2 state show that the form factors have significant differences. The results imply that elastic magnetic electron scattering can be a possible way to study the 2s1/2 and 1d3/2 level inversion and the spin-parity values of 37-47P. The results can also provide new tests as to what extent the RMF model, along with its various parameter sets, is valid for describing the nuclear structures. In addition, the contributions of the upper and lower components of the Dirac four-spinors to the form factors and the isotopic shifts of the magnetic form factors are discussed.

Noncommutative Wilson lines in higher-spin theory and correlation functions of conserved currents for free conformal fields

NASA Astrophysics Data System (ADS)

Bonezzi, Roberto; Boulanger, Nicolas; De Filippi, David; Sundell, Per

2017-11-01

We first prove that, in Vasiliev’s theory, the zero-form charges studied in Sezgin E and Sundell P 2011 (arXiv:1103.2360 [hep-th]) and Colombo N and Sundell P 20 (arXiv:1208.3880 [hep-th]) are twisted open Wilson lines in the noncommutative Z space. This is shown by mapping Vasiliev’s higher-spin model on noncommutative Yang-Mills theory. We then prove that, prior to Bose-symmetrising, the cyclically-symmetric higher-spin invariants given by the leading order of these n-point zero-form charges are equal to corresponding cyclically-invariant building blocks of n-point correlation functions of bilinear operators in free conformal field theories (CFT) in three dimensions. On the higher spin gravity side, our computation reproduces the results of Didenko V and Skvortsov E 2013 J. High Energy Phys. JHEP04(2013)158 using an alternative method amenable to the computation of subleading corrections obtained by perturbation theory in normal order. On the free CFT side, our proof involves the explicit computation of the separate cyclic building blocks of the correlation functions of n conserved currents in arbitrary dimension d>2 using polarization vectors, which is an original result. It is shown to agree, for d=3 , with the results obtained in Gelfond O A and Vasiliev M A 2013 Nucl. Phys. B 876 871-917 in various dimensions and where polarization spinors were used.

Two-dimensional solitons in dipolar Bose-Einstein condensates with spin-orbit coupling

NASA Astrophysics Data System (ADS)

Jiang, Xunda; Fan, Zhiwei; Chen, Zhaopin; Pang, Wei; Li, Yongyao; Malomed, Boris A.

2016-02-01

We report families of two-dimensional (2D) composite solitons in spinor dipolar Bose-Einstein condensates, with two localized components linearly mixed by the spin-orbit coupling (SOC), and the intrinsic nonlinearity represented by the dipole-dipole interaction (DDI) between atomic magnetic moments polarized in plane by an external magnetic field. Recently, stable solitons were predicted in the form of semivortices (composites built of coupled fundamental and vortical components) in the 2D system combining the SOC and contact attractive interactions. Replacing the latter by the anisotropic long-range DDI, we demonstrate that, for a fixed norm of the soliton, the system supports a continuous family of stable spatially asymmetric vortex solitons (AVSs), parameterized by an offset of the pivot of the vortical component relative to its fundamental counterpart. The offset is limited by a certain maximum value, while the energy of the AVS practically does not depend on the offset. At small values of the norm, the vortex solitons are subject to a weak oscillatory instability. In the present system, with the Galilean invariance broken by the SOC, the composite solitons are set in motion by a kick the strength of which exceeds a certain depinning value. The kicked solitons feature a negative effective mass, drifting along a spiral trajectory opposite to the direction of the kick. A critical angular velocity, up to which the semivortices may follow rotation of the polarizing magnetic field, is found too.

Scalar formalism for non-Abelian gauge theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hostler, L.C.

1986-09-01

The gauge field theory of an N-italic-dimensional multiplet of spin- 1/2 particles is investigated using the Klein--Gordon-type wave equation )Pi x (1+i-italicsigma) x Pi+m-italic/sup 2/)Phi = 0, Pi/sub ..mu../equivalentpartial/partiali-italicx-italic/sub ..mu../-e-italicA-italic/sub ..mu../, investigated before by a number of authors, to describe the fermions. Here Phi is a 2 x 1 Pauli spinor, and sigma repesents a Lorentz spin tensor whose components sigma/sub ..mu..//sub ..nu../ are ordinary 2 x 2 Pauli spin matrices. Feynman rules for the scalar formalism for non-Abelian gauge theory are derived starting from the conventional field theory of the multiplet and converting it to the new description. Themore » equivalence of the new and the old formalism for arbitrary radiative processes is thereby established. The conversion to the scalar formalism is accomplished in a novel way by working in terms of the path integral representation of the generating functional of the vacuum tau-functions, tau(2,1, xxx 3 xxx)equivalent<0-chemically bondT-italic(Psi/sub in/(2) Psi-bar/sub in/(1) xxx A-italic/sub ..mu../(3)/sub in/ xxx S-italic)chemically bond0->, where Psi/sub in/ is a Heisenberg operator belonging to a 4N-italic x 1 Dirac wave function of the multiplet. The Feynman rules obtained generalize earlier results for the Abelian case of quantum electrodynamics.« less

Origin of families of fermions and their mass matrices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bracic, A. Borstnik; Borstnik, N. S. Mankoc; Department of Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana

We are proposing a new way of describing families of quarks and leptons, using the approach unifying all the internal degrees of freedom, proposed by one of us [N. Mankoc Borstnik, Phys. Lett. B 292, 25 (1992).][N. Mankoc-Borstnik, J. Math. Phys. (N.Y.) 34, 3731 (1993).][N. Mankoc Borstnik, J. Math. Phys. (N.Y.) 36, 1593 (1995).][N. S. Mankoc Borstnik, Mod. Phys. Lett. A 10, 587 (1995).][N. S. Mankoc Borstnik and S. Fajfer, Nuovo Cimento Soc. Ital. Fis. B 112, 1637 (1997).][A. Borstnik and N. S. Mankoc Borstnik, in Proceedings to the International Workshop on ''What Comes Beyond the Standard Model, Bled, Slovenia,more » 1998, edited by N. Mankoc Borstnik, H. B. Nielsen, and C. Froggatt (DMFA, Zaloznistvo, 1999), p. 52.][N. S. Mankoc Borstnik and H. B. Nielsen, Phys. Rev. 62, 04010 (2000).][N. S. Mankoc Borstnik, Int. J. Theor. Phys. 40, 315 (2001), and references therein.][A. Borstnik and N. S. Mankoc Borstnik, in Proceedings to the International Workshop on ''What Comes Beyond the Standard Model'', Bled 2000, 2001, 2002 Volume 2, edited by N. Mankoc Borstnik, H. B. Nielsen, C. Froggatt, and D. Lukman (DMFA, Zaloznistvo, 2002), p. 27 and the paper (unpublished).][A. Borstnik and N. S. Mankoc Borstnik, in Proceedings to the Euroconference on Symmetries Beyond the Standard Model, Portoroz, 2003 edited by N. Mankoc Borstnik, H. B. Nielsen, C. Froggatt, and D. Lukman (DMFA, Zaloznistvo, 2003), pp. 27-51.]. Spinors, living in d(=1+13)-dimensional space, carry in this approach only the spin and interact with only the gravity through vielbeins and two kinds of the spin connection fields--the gauge fields of the Poincare group (p{sup a},S{sup ab}) and the second kind of the Clifford algebra objects (S-tilde{sup ab}). All the quarks and the leptons of one family appear in one Weyl representation of a chosen handedness of the Lorentz group, if analyzed with respect to the standard model gauge groups, which are subgroups of the group SO(1,13): the right handed (with respect to SO(1,3)) weak chargeless quarks and leptons and the left handed weak charged quarks and leptons (with the right handed neutrino included). A part of the starting Lagrange density of a Weyl spinor in d=1+13 transforms right handed quarks and leptons into left handed quarks and leptons manifesting as the Yukawa couplings of the standard model. A kind of the Clifford algebra objects generates families of quarks and leptons and contributes to diagonal and off-diagonal Yukawa couplings. The approach predicts an even number of families, treating leptons and quarks equivalently (we do not study a possible appearance of Majorana fermions yet). In this paper we investigate within this approach the appearance of the Yukawa couplings within one family of quarks and leptons as well as among the families (without assuming any Higgs fields like in the standard model). We present the mass matrices for four families and investigate whether our way of generating families might explain the origin of families of quarks and leptons as well as their observed properties--the masses and the mixing matrices. Numerical results are presented in Ref. [M. Breskvar, D. Lukman, and N. S. Mankoc Borstnik, hep-ph/0606159.].« less

Book Review:

NASA Astrophysics Data System (ADS)

Parthasarathy, R.

2005-06-01

This book gives a clear exposition of quantum field theory at the graduate level and the contents could be covered in a two semester course or, with some effort, in a one semester course. The book is well organized, and subtle issues are clearly explained. The margin notes are very useful, and the problems given at the end of each chapter are relevant and help the student gain an insight into the subject. The solutions to these problems are given in chapter 12. Care is taken to keep the numerical factors and notation very clear. Chapter 1 gives a clear overview and typical scales in high energy physics. Chapter 2 presents an excellent account of the Lorentz group and its representation. The decomposition of Lorentz tensors under SO(3) and the subsequent spinorial representations are introduced with clarity. After giving the field representation for scalar, Weyl, Dirac, Majorana and vector fields, the Poincaré group is introduced. Representations of 1-particle states using m2 and the Pauli Lubanski vector, although standard, are treated lucidly. Classical field theory is introduced in chapter 3 and a careful treatment of the Noether theorem and the energy momentum tensor are given. After covering real and complex scalar fields, the author impressively introduces the Dirac spinor via the Weyl spinor; Abelian gauge theory is also introduced. Chapter 4 contains the essentials of free field quantization of real and complex scalar fields, Dirac fields and massless Weyl fields. After a brief discussion of the CPT theorem, the quantization of electromagnetic field is carried out both in radiation gauge and Lorentz gauge. The presentation of the Gupta Bleuler method is particularly impressive; the margin notes on pages 85, 100 and 101 invaluable. Chapter 5 considers the essentials of perturbation theory. The derivation of the LSZ reduction formula for scalar field theory is clearly expressed. Feynman rules are obtained for the λphi4 theory in detail and those of QED briefly. The basic idea of renormalization is explained using the λphi4 theory as an example. There is a very lucid discussion on the `running coupling' constant in section 5.9. Chapter 6 explains the use of the matrix elements, formally given in the previous chapter, to compute decay rates and cross sections. The exposition is such that the reader will have no difficulty in following the steps. However, bearing in mind the continuity of the other chapters, this material could have been consigned to an appendix. In the short chapter 7, the QED Lagrangian is shown to respect P, C and T invariance. One-loop divergences are described. Dimensional and Pauli Villars regularization are introduced and explained, although there is no account of their use in evaluating a typical one-loop divergent integral. Chapter 8 describes the low energy limit of the Weinberg Salam theory. Examples for μ-→ e-barnueν μ, π+→ l+νl and K0→ π-l+νl are explicitly solved, although the serious reader should work them out independently. On page 197 the `V-A structure of the currents proposed by Feynman and Gell-Mann' is stated; the first such proposal was by E C G Sudarshan and R E Marshak. In chapter 9 the path integral quantization method is developed. After deriving the transition amplitude as the sum over all paths, in quantum mechanics, a demonstration that the integration of functions in the path integral gives the expectation value of the time ordered product of the corresponding operators is given and applied to real scalar free field theory to get the Feynman propagator. Then the Euclidean formulation is introduced and its `tailor made' role in critical phenomena is illustrated with the 2-d Ising model as an example, including the RG equation. Chapter 10 introduces Yang Mills theory. After writing down the typical gauge invariant Lagrangian and outlining the ingredients of QCD, the adjoint representation for fields is given. It could have been made complete by giving the Feynman rules for the cubic and quartic vertices for non-Abelian gauge fields, although the reader can obtain them from the last term in equation 10.27. In chapter 11, spontaneous symmetry breaking in quantum field theory is described. The difference in quantum mechanics and QFT with respect to the degenerate vacua is clearly brought out by considering the tunnelling amplitude between degenerate vacua. This is very good, as this aspect is mostly overlooked in many textbooks. The Goldstone theorem is then illustrated by an example. The Higgs mechanism is explained in Abelian and non-Abelian (SU(2)) gauge theories and the situation in SU(2)xU(1) gauge theory is discussed. This book certainly covers most of the modern developments in quantum field theory. The reader will be able to follow the content and apply it to specific problems. The bibliography is certainly useful. It will be an asset to libraries in teaching and research institutions.

Tensor and Spin Representations of SO(4) and Discrete Quantum Gravity

NASA Astrophysics Data System (ADS)

Lorente, M.; Kramer, P.

Starting from the defining transformations of complex matrices for the SO(4) group, we construct the fundamental representation and the tensor and spinor representations of the group SO(4). Given the commutation relations for the corresponding algebra, the unitary representations of the group in terms of the generalized Euler angles are constructed. These mathematical results help us to a more complete description of the Barret-Crane model in Quantum Gravity. In particular a complete realization of the weight function for the partition function is given and a new geometrical interpretation of the asymptotic limit for the Regge action is presented.

Relativistic Coulomb Problem for Z Larger than 137

NASA Astrophysics Data System (ADS)

Alhaidari, A. D.

We propose a relativistic one-parameter Hermitian theory for the Coulomb problem with an electric charge greater than 137. In the nonrelativistic limit, the theory becomes identical to the Schrödinger-Coulomb problem for all Z. Moreover, it agrees with the Dirac-Coulomb problem to order (αZ)2, where α is the fine structure constant. The vacuum in the theory is stable and does not suffer from the "charged vacuum" problem for all Z. Moreover, transition between positive and negative energy states could be eliminated. The relativistic bound states energy spectrum and corresponding spinor wave functions are obtained.

G2-structures for N  =  1 supersymmetric AdS4 solutions of M-theory

NASA Astrophysics Data System (ADS)

Grigorian, Sergey

2018-04-01

We study the N  =  1 supersymmetric solutions of D  =  11 supergravity obtained as a warped product of four-dimensional anti-de Sitter space with a seven-dimensional Riemannian manifold M. Using the octonion bundle structure on M we reformulate the Killing spinor equations in terms of sections of the octonion bundle on M. The solutions then define a single complexified G 2-structure on M or equivalently two real G 2-structures. We then study the torsion of these G 2-structures and the relationships between them.

Bootstrapping 3D fermions

DOE PAGES

Iliesiu, Luca; Kos, Filip; Poland, David; ...

2016-03-17

We study the conformal bootstrap for a 4-point function of fermions in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ × ψ OPE, and also on the central charge C T. We observe features in our bounds that coincide with scaling dimensions in the GrossNeveu models at large N. Finally, we also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.

Spinors in Hilbert Space

NASA Astrophysics Data System (ADS)

Plymen, Roger; Robinson, Paul

1995-01-01

Infinite-dimensional Clifford algebras and their Fock representations originated in the quantum mechanical study of electrons. In this book, the authors give a definitive account of the various Clifford algebras over a real Hilbert space and of their Fock representations. A careful consideration of the latter's transformation properties under Bogoliubov automorphisms leads to the restricted orthogonal group. From there, a study of inner Bogoliubov automorphisms enables the authors to construct infinite-dimensional spin groups. Apart from assuming a basic background in functional analysis and operator algebras, the presentation is self-contained with complete proofs, many of which offer a fresh perspective on the subject.

Dynamic Stabilization of a Quantum Many-Body Spin System

NASA Astrophysics Data System (ADS)

Hoang, T. M.; Gerving, C. S.; Land, B. J.; Anquez, M.; Hamley, C. D.; Chapman, M. S.

2013-08-01

We demonstrate dynamic stabilization of a strongly interacting quantum spin system realized in a spin-1 atomic Bose-Einstein condensate. The spinor Bose-Einstein condensate is initialized to an unstable fixed point of the spin-nematic phase space, where subsequent free evolution gives rise to squeezing and quantum spin mixing. To stabilize the system, periodic microwave pulses are applied that rotate the spin-nematic many-body fluctuations and limit their growth. The stability diagram for the range of pulse periods and phase shifts that stabilize the dynamics is measured and compares well with a stability analysis.

Asymptotic structure of N=2 supergravity in 3D: extended super-BMS3 and nonlinear energy bounds

NASA Astrophysics Data System (ADS)

Fuentealba, Oscar; Matulich, Javier; Troncoso, Ricardo

2017-09-01

The asymptotically flat structure of N=(2,0) supergravity in three spacetime dimensions is explored. The asymptotic symmetries are found to be spanned by an extension of the super-BMS3 algebra, endowed with two independent affine û(1) currents of electric and magnetic type. These currents are associated to U(1) fields being even and odd under parity, respectively. Remarkably, although the U(1) fields do not generate a backreaction on the metric, they provide nontrivial Sugawara-like contributions to the BMS3 generators, and hence to the energy and the angular momentum. Consequently, the entropy of flat cosmological spacetimes endowed with U(1) fields acquires a nontrivial dependence on the zero modes of the û(1) charges. If the spin structure is odd, the ground state corresponds to Minkowski spacetime, and although the anticommutator of the canonical supercharges is linear in the energy and in the electric-like û(1) charge, the energy becomes bounded from below by the energy of the ground state shifted by the square of the electric-like û(1) charge. If the spin structure is even, the same bound for the energy generically holds, unless the absolute value of the electric-like charge is less than minus the mass of Minkowski spacetime in vacuum, so that the energy has to be nonnegative. The explicit form of the global and asymptotic Killing spinors is found for a wide class of configurations that fulfills our boundary conditions, and they exist precisely when the corresponding bounds are saturated. It is also shown that the spectra with periodic or antiperiodic boundary conditions for the fermionic fields are related by spectral flow, in a similar way as it occurs for the N=2 super-Virasoro algebra. Indeed, our supersymmetric extension of BMS3 can be recovered from the Inönü-Wigner contraction of the superconformal algebra with N=(2,2) , once the fermionic generators of the right copy are truncated.

Topological collective plasmons in bipartite chains of metallic nanoparticles

NASA Astrophysics Data System (ADS)

Downing, Charles A.; Weick, Guillaume

2017-03-01

We study a bipartite linear chain constituted by spherical metallic nanoparticles, where each nanoparticle supports a localized surface plasmon. The near-field dipolar interaction between the localized surface plasmons gives rise to collective plasmons, which are extended over the whole nanoparticle array. We derive analytically the spectrum and the eigenstates of the collective plasmonic excitations. At the edge of the Brillouin zone, the spectrum is of a pseudorelativistic nature similar to that present in the electronic band structure of polyacetylene. We find the effective Dirac Hamiltonian for the collective plasmons and show that the corresponding spinor eigenstates represent one-dimensional Dirac-like massive bosonic excitations. Therefore, the plasmonic lattice exhibits similar effects to those found for electrons in one-dimensional Dirac materials, such as the ability for transmission with highly suppressed backscattering due to Klein tunneling. We also show that the system is governed by a nontrivial Zak phase, which predicts the manifestation of edge states in the chain. When two dimerized chains with different topological phases are connected, we find the appearance of the bosonic version of a Jackiw-Rebbi midgap state. We further investigate the radiative and nonradiative lifetimes of the collective plasmonic excitations and comment on the challenges for experimental realization of the topological effects found theoretically.

Understanding the Electronic Structure of 4d Metal Complexes: From Molecular Spinors to L-Edge Spectra of a di-Ru Catalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alperovich, Igor; Smolentsev, Grigory; Moonshiram, Dooshaye

2015-09-17

L{sub 2,3}-edge X-ray absorption spectroscopy (XAS) has demonstrated unique capabilities for the analysis of the electronic structure of di-Ru complexes such as the blue dimer cis,cis-[Ru{sub 2}{sup III}O(H{sub 2}O){sub 2}(bpy){sub 4}]{sup 4+} water oxidation catalyst. Spectra of the blue dimer and the monomeric [Ru(NH{sub 3}){sub 6}]{sup 3+} model complex show considerably different splitting of the Ru L{sub 2,3} absorption edge, which reflects changes in the relative energies of the Ru 4d orbitals caused by hybridization with a bridging ligand and spin-orbit coupling effects. To aid the interpretation of spectroscopic data, we developed a new approach, which computes L{sub 2,3}-edges XASmore » spectra as dipole transitions between molecular spinors of 4d transition metal complexes. This allows for careful inclusion of the spin-orbit coupling effects and the hybridization of the Ru 4d and ligand orbitals. The obtained theoretical Ru L{sub 2,3}-edge spectra are in close agreement with experiment. Critically, existing single-electron methods (FEFF, FDMNES) broadly used to simulate XAS could not reproduce the experimental Ru L-edge spectra for the [Ru(NH{sub 3}){sub 6}]{sup 3+} model complex nor for the blue dimer, while charge transfer multiplet (CTM) calculations were not applicable due to the complexity and low symmetry of the blue dimer water oxidation catalyst. We demonstrated that L-edge spectroscopy is informative for analysis of bridging metal complexes. The developed computational approach enhances L-edge spectroscopy as a tool for analysis of the electronic structures of complexes, materials, catalysts, and reactive intermediates with 4d transition metals.« less

Dynamic localization in optical and Zeeman lattices in the presence of spin-orbit coupling

NASA Astrophysics Data System (ADS)

Kartashov, Yaroslav V.; Konotop, Vladimir V.; Zezyulin, Dmitry A.; Torner, Lluis

2016-12-01

The dynamic localization of a two-level atom in a periodic potential under the action of spin-orbit coupling and a weak harmonically varying linear force is studied. We consider optical and Zeeman potentials that are either in phase or out of phase in two spinor components, respectively. The expectation value for the position of the atom after one oscillation period of the linear force is recovered in authentic resonances or in pseudoresonances. The frequencies of the linear force corresponding to authentic resonances are determined by the band structure of the periodic potential and are affected by the spin-orbit coupling. The width or dispersion of the wave packet in authentic resonances is usually minimal. The frequencies corresponding to pseudoresonances do not depend on the type of potential and on the strength of the spin-orbit coupling, while the evolution of excitations at the corresponding frequencies is usually accompanied by significant dispersion. Pseudoresonances are determined by the initial phase of the linear force and by the quasimomentum of the wave packet. Due to the spinor nature of the system, the motion of the atom is accompanied by periodic, but not harmonic, spin oscillations. Under the action of spin-orbit coupling the oscillations of the wave packet can be nearly completely suppressed in optical lattices. Dynamic localization in Zeeman lattices is characterized by doubling of the resonant oscillation periods due to band crossing at the boundary of the Brillouin zone. We also show that higher harmonics in the Fourier expansion of the energy band lead to effective dispersion, which can be strong enough to prevent dynamic localization of the Bloch wave packet.

Global and local approaches to population analysis: Bonding patterns in superheavy element compounds

NASA Astrophysics Data System (ADS)

Oleynichenko, Alexander; Zaitsevskii, Andréi; Romanov, Stepan; Skripnikov, Leonid V.; Titov, Anatoly V.

2018-03-01

Relativistic effective atomic configurations of superheavy elements Cn, Nh and Fl and their lighter homologues (Hg, Tl and Pb) in their simple compounds with fluorine and oxygen are determined using the analysis of local properties of molecular Kohn-Sham density matrices in the vicinity of heavy nuclei. The difference in populations of atomic spinors with the same orbital angular momentum and different total angular momenta is demonstrated to be essential for understanding the peculiarities of chemical bonding in superheavy element compounds. The results are fully compatible with those obtained by the relativistic iterative version of conventional projection analysis of global density matrices.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szankowski, Piotr; Trippenbach, Marek; Infeld, Eryk

We introduce a class of solitonlike entities in spinor three-component Bose-Einstein condensates. These entities generalize well-known solitons. For special values of coupling constants, the system considered is completely integrable and supports N soliton solutions. The one-soliton solutions can be generalized to systems with different values of coupling constants. However, they no longer interact elastically. When two so-generalized solitons collide, a spin component oscillation is observed in both emerging entities. We propose to call these newfound entities oscillatons. They propagate without dispersion and retain their character after collisions. We derive an exact mathematical model for oscillatons and show that the well-knownmore » one-soliton solutions are a particular case.« less

Relativistic coupled cluster theory based on the no-pair Dirac-Coulomb-Breit Hamiltonian: Relativistic pair correlation energies of the Xe atom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eliav, E.; Kaldor, U.; Ishikawa, Y.

1994-12-31

Relativistic pair correlation energies of Xe were computed by employing a recently developed relativistic coupled cluster theory based on the no-pair Dirac-Coulomb-Breit Hamiltonian. The matrix Dirac-Fock-Breit SCF and relativistic coupled cluster calculations were performed by means of expansion in basis sets of well-tempered Gaussian spinors. A detailed study of the pair correlation energies in Xe is performed, in order to investigate the effects of the low-frequency Breit interaction on the correlation energies of Xe. Nonadditivity of correlation and relativistic (particularly Breit) effects is discussed.

Separation of variables for the Dirac equation in an extended class of Lorentzian metrics with local rotational symmetry

NASA Astrophysics Data System (ADS)

Iyer, B. R.; Kamran, N.

1991-09-01

The question of the separability of the Dirac equation in metrics with local rotational symmetry is reexamined by adapting the analysis of Kamran and McLenaghan [J. Math. Phys. 25, 1019 (1984)] for the metrics admitting a two-dimensional Abelian local isometry group acting orthogonally transitively. This generalized treatment, which involves the choice of a suitable system of local coordinates and spinor frame, allows one to establish the separability of the Dirac equation within the class of metrics for which the previous analysis of Iyer and Vishveshwara [J. Math. Phys. 26, 1034 (1985)] had left the question of separability open.

Hyperfine state entanglement of spinor BEC and scattering atom

NASA Astrophysics Data System (ADS)

Li, Zhibing; Bao, Chengguang; Zheng, Wei

2018-05-01

Condensate of spin-1 atoms frozen in a unique spatial mode may possess large internal degrees of freedom. The scattering amplitudes of polarized cold atoms scattered by the condensate are obtained with the method of fractional parentage coefficients that treats the spin degrees of freedom rigorously. Channels with scattering cross sections enhanced by the square of the atom number of the condensate are found. Entanglement between the condensate and the propagating atom can be established by scattering. Entanglement entropy is analytically obtained for arbitrary initial states. Our results also give a hint for the establishment of quantum thermal ensembles in the hyperfine space of spin states.

Nonrelativistic approaches derived from point-coupling relativistic models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lourenco, O.; Dutra, M.; Delfino, A.

2010-03-15

We construct nonrelativistic versions of relativistic nonlinear hadronic point-coupling models, based on new normalized spinor wave functions after small component reduction. These expansions give us energy density functionals that can be compared to their relativistic counterparts. We show that the agreement between the nonrelativistic limit approach and the Skyrme parametrizations becomes strongly dependent on the incompressibility of each model. We also show that the particular case A=B=0 (Walecka model) leads to the same energy density functional of the Skyrme parametrizations SV and ZR2, while the truncation scheme, up to order {rho}{sup 3}, leads to parametrizations for which {sigma}=1.

Formation of a solar Hα filament from orphan penumbrae

NASA Astrophysics Data System (ADS)

Buehler, D.; Lagg, A.; van Noort, M.; Solanki, S. K.

2016-05-01

Aims: The formation and evolution of an Hα filament in active region (AR) 10953 is described. Methods: Observations from the Solar Optical Telescope (SOT) aboard the Hinode satellite starting from UT 18:09 on 27th April 2007 until UT 06:08 on 1st May 2007 were analysed. 20 scans of the 6302 Å Fe I line pair recorded by SOT/SP were inverted using the spatially coupled version of the SPINOR code. The inversions were analysed together with co-spatial SOT/BFI G-band and Ca II H and SOT/NFI Hα observations. Results: Following the disappearance of an initial Hα filament aligned along the polarity inversion line (PIL) of the AR, a new Hα filament formed in its place some 20 h later, which remained stable for, at least, another 1.5 days. The creation of the new Hα filament was driven by the ascent of horizontal magnetic fields from the photosphere into the chromosphere at three separate locations along the PIL. The magnetic fields at two of these locations were situated directly underneath the initial Hα filament and formed orphan penumbrae already aligned along the Hα filament channel. The 700 G orphan penumbrae were stable and trapped in the photosphere until the disappearance of the overlying initial Hα filament, after which they started to ascend into the chromosphere at 10 ± 5 m/s. Each ascent was associated with a simultaneous magnetic flux reduction of up to 50% in the photosphere. The ascended orphan penumbrae formed dark seed structures in Hα in parallel with the PIL, which elongated and merged to form an Hα filament. The filament channel featured horizontal magnetic fields of on average 260 G at log (τ) = -2 suspended above the nearly field-free lower photosphere. The fields took on an overall inverse configuration at log (τ) = -2 suggesting a flux rope topology for the new Hα filament. The destruction of the initial Hα filament was likely caused by the flux emergence at the third location along the PIL. Conclusions: We present a new interpretation of the Hα filament formation in AR 10953 whereby the mainly horizontal fields of orphan penumbrae, aligned along the Hα filament channel, ascend into the chromosphere, forming seed fragments for a new, second Hα filament. The orphan penumbral fields ascend into the chromosphere ~9-24 h before the Hα filament is fully formed.

Deformed twistors and higher spin conformal (super-)algebras in four dimensions

DOE PAGES

Govil, Karan; Gunaydin, Murat

2015-03-05

Massless conformal scalar field in d = 4 corresponds to the minimal unitary representation (minrep) of the conformal group SU(2, 2) which admits a one-parameter family of deformations that describe massless fields of arbitrary helicity. The minrep and its deformations were obtained by quantization of the nonlinear realization of SU(2, 2) as a quasiconformal group in arXiv:0908.3624. We show that the generators of SU(2,2) for these unitary irreducible representations can be written as bilinears of deformed twistorial oscillators which transform nonlinearly under the Lorentz group and apply them to define and study higher spin algebras and superalgebras in AdS 5.more » The higher spin (HS) algebra of Fradkin-Vasiliev type in AdS 5 is simply the enveloping algebra of SU(2, 2) quotiented by a two-sided ideal (Joseph ideal) which annihilates the minrep. We show that the Joseph ideal vanishes identically for the quasiconformal realization of the minrep and its enveloping algebra leads directly to the HS algebra in AdS 5. Furthermore, the enveloping algebras of the deformations of the minrep define a one parameter family of HS algebras in AdS 5 for which certain 4d covariant deformations of the Joseph ideal vanish identically. These results extend to superconformal algebras SU(2, 2|N) and we find a one parameter family of HS superalgebras as enveloping algebras of the minimal unitary supermultiplet and its deformations. Our results suggest the existence of a family of (supersymmetric) HS theories in AdS 5 which are dual to free (super)conformal field theories (CFTs) or to interacting but integrable (supersymmetric) CFTs in 4d. We also discuss the corresponding picture in HS algebras in AdS 4 where the corresponding 3d conformal group Sp(4,R) admits only two massless representations (minreps), namely the scalar and spinor singletons.« less

The zero-action hypothesis and high-temperature thermodynamics in the heterotic superstring theory

NASA Astrophysics Data System (ADS)

Pollock, M. D.

2005-07-01

The effective action S for the Einstein theory of gravity coupled to massless scalar fields phi, spinor fields ψ and gauge vector fields Fij describing radiation, so that FijFij = 0, vanishes identically after substitution from the classical equations of motion, thus allowing a perfect fluid for which the energy density ρ and pressure p = (γ - 1)ρ are related by values of the adiabatic index throughout the range 4/3 <= γ <= 2. In the heterotic superstring theory, four-point gravitational interactions generate a tree-level quadratic, higher-derivative contribution to the Lagrangian, after reduction to four dimensions, whose form, unchanged at one-loop level, is {\\cal R}^2 = B(R^2 -R_{ij}R^{ij}) = {1 \\over 6} B (\\gamma-2)(\\gamma-1) \\kappa^4 \\rho^2 , where the constant B ap 1 for a three-generation Calabi Yau manifold, and which thus constitutes a type of anomaly. The zero-action hypothesis requires the theory to be free of such anomalies, and thus predicts that the Universe started off in the state p = ρ discussed by Zel'dovich, characterized by the maximum value γ = 2 consistent with causality. Applying classical thermodynamics to a perfect fluid, we find that ρ, p and hence also the Helmholtz free-energy density f ≡ -p, scale with temperature as Tγ/γ-1, leading to the prediction that f ~ T2, which is exactly verified by the calculation of Atick and Witten, valid at genus-one in the high-temperature limit T Gt TH, after Euclideanizing the time coordinate, where TH is the Hagedorn temperature. The response of the action to the operators T, C and P is also discussed, T-invariance requiring γ = 2 and hence S = 0, and P-invariance requiring S = 0, showing that the zero-action hypothesis can be understood in terms of these discrete symmetries.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Govil, Karan; Gunaydin, Murat

Massless conformal scalar field in d = 4 corresponds to the minimal unitary representation (minrep) of the conformal group SU(2, 2) which admits a one-parameter family of deformations that describe massless fields of arbitrary helicity. The minrep and its deformations were obtained by quantization of the nonlinear realization of SU(2, 2) as a quasiconformal group in arXiv:0908.3624. We show that the generators of SU(2,2) for these unitary irreducible representations can be written as bilinears of deformed twistorial oscillators which transform nonlinearly under the Lorentz group and apply them to define and study higher spin algebras and superalgebras in AdS 5.more » The higher spin (HS) algebra of Fradkin-Vasiliev type in AdS 5 is simply the enveloping algebra of SU(2, 2) quotiented by a two-sided ideal (Joseph ideal) which annihilates the minrep. We show that the Joseph ideal vanishes identically for the quasiconformal realization of the minrep and its enveloping algebra leads directly to the HS algebra in AdS 5. Furthermore, the enveloping algebras of the deformations of the minrep define a one parameter family of HS algebras in AdS 5 for which certain 4d covariant deformations of the Joseph ideal vanish identically. These results extend to superconformal algebras SU(2, 2|N) and we find a one parameter family of HS superalgebras as enveloping algebras of the minimal unitary supermultiplet and its deformations. Our results suggest the existence of a family of (supersymmetric) HS theories in AdS 5 which are dual to free (super)conformal field theories (CFTs) or to interacting but integrable (supersymmetric) CFTs in 4d. We also discuss the corresponding picture in HS algebras in AdS 4 where the corresponding 3d conformal group Sp(4,R) admits only two massless representations (minreps), namely the scalar and spinor singletons.« less

Four-Component Relativistic State-Specific Multireference Perturbation Theory with a Simplified Treatment of Static Correlation.

PubMed

Ghosh, Anirban; Sinha Ray, Suvonil; Chaudhuri, Rajat K; Chattopadhyay, Sudip

2017-02-23

The relativistic multireference (MR) perturbative approach is one of the most successful tools for the description of computationally demanding molecular systems of heavy elements. We present here the ground state dissociation energy surfaces, equilibrium bond lengths, harmonic frequencies, and dissociation energies of Ag 2 , Cu 2 , Au 2 , and I 2 computed using the four-component (4c) relativistic spinors based state-specific MR perturbation theory (SSMRPT) with improved virtual orbital complete active space configuration interaction (IVO-CASCI) functions. The IVO-CASCI method is a simple, robust, useful and lower cost alternative to the complete active space self-consistent field approach for treating quasidegenerate situations. The redeeming features of the resulting method, termed as 4c-IVO-SSMRPT, lies in (i) manifestly size-extensivity, (ii) exemption from intruder problems, (iii) the freedom of convenient multipartitionings of the Hamiltonian, (iv) flexibility of the relaxed and unrelaxed descriptions of the reference coefficients, and (v) manageable cost/accuracy ratio. The present method delivers accurate descriptions of dissociation processes of heavy element systems. Close agreement with reference values has been found for the calculated molecular constants indicating that our 4c-IVOSSMRPT provides a robust and economic protocol for determining the structural properties for the ground state of heavy element molecules with eloquent MR character as it treats correlation and relativity on equal footing.

Chiral magnetic effect in condensed matter systems

NASA Astrophysics Data System (ADS)

Li, Qiang; Kharzeev, Dmitri E.

2016-12-01

The chiral magnetic effect (CME) is the generation of electrical current induced by chirality imbalance in the presence of magnetic field. It is a macroscopic manifestation of the quantum chiral anomaly [S. L. Adler. Axial-vector vertex in spinor electrodynamics. Physical Review, 177, 2426 (1969), J. S. Bell and R. Jackiw. A PCAC puzzle: π 0 γγin the σ-model. Il Nuovo Cimento A, 60, 47-61 (1969)] in systems possessing charged chiral fermions. In quark-gluon plasma containing nearly massless quarks, the chirality imbalance is sourced by the topological transitions. In condensed matter systems, the chiral quasiparticles emerge in gapless semiconductors with two energy bands having pointlike degeneracies opening the path to the study of chiral anomaly [H. B. Nielsen and M. Ninomiya. The Adler-Bell-Jackiw anomaly and Weyl fermions in a crystal. Physics Letters B, 130, 389-396 (1983)]. Recently, these novel materials - so-called Dirac and Weyl semimetals have been discovered experimentally, are suitable for the investigation of the CME in condensed matter experiments. Here we report on the first experimental observation of the CME in a 3D Dirac semimetal ZrTe5 [Q. Li, D. E. Kharzeev, C. Zhang, Y. Huang, I. Pletikosić, A. V. Fedorov, R. D. Zhong, J. A. Schneeloch, G. D. Gu, and T. Valla. Chiral magnetic effect in ZrTe5. Nature Physics (2016) doi:10.1038/nphys3648].

Helicity amplitudes for QCD with massive quarks

NASA Astrophysics Data System (ADS)

Ochirov, Alexander

2018-04-01

The novel massive spinor-helicity formalism of Arkani-Hamed, Huang and Huang provides an elegant way to calculate scattering amplitudes in quantum chromodynamics for arbitrary quark spin projections. In this note we compute two families of tree-level QCD amplitudes with one massive quark pair and n - 2 gluons. The two cases include all gluons with identical helicity and one opposite-helicity gluon being color-adjacent to one of the quarks. Our results naturally incorporate the previously known amplitudes for both quark spins quantized along one of the gluonic momenta. In the all-multiplicity formulae presented here the spin quantization axes can be tuned at will, which includes the case of the definite-helicity quark states.

5-brane webs for 5d N = 1 G 2 gauge theories

NASA Astrophysics Data System (ADS)

Hayashi, Hirotaka; Kim, Sung-Soo; Lee, Kimyeong; Yagi, Futoshi

2018-03-01

We propose 5-brane webs for 5d N = 1 G 2 gauge theories. From a Higgsing of the SO(7) gauge theory with a hypermultiplet in the spinor representation, we construct two types of 5-brane web configurations for the pure G 2 gauge theory using an O5-plane or an \\tilde{O5} -plane. Adding flavors to the 5-brane web for the pure G 2 gauge theory is also discussed. Based on the obtained 5-brane webs, we compute the partition functions for the 5d G 2 gauge theories using the recently suggested topological vertex formulation with an O5-plane, and we find agreement with known results.

Anomalous Topological Currents in Graphene Superlattices

NASA Astrophysics Data System (ADS)

Samutpraphoot, Polnop; Song, Justin; Levitov, Leonid

2014-03-01

Berry's phases naturally arise from the spinor structure of Dirac systems, yet observation of non-trivial Berry's phase effects in the transport characteristics of Dirac systems, such as the Valley Hal effect, has proved elusive. Recently, layered graphene heterostructures have emerged as a promising setting to observe novel electron dynamics. We will discuss how novel features in Berry's curvature arise in Graphene/h-BN superlattices to allow long range topological currents to develop. Non-intuitively, we find superlattice mini-bands that have non-trivial Valley Chern number even though the sub-lattice asymmetric potential oscillates in sign. This results in clear non-local transport signatures for the topological character of the bands formed in Graphene/h-BN heterostructures.

Connecting the ambitwistor and the sectorized heterotic strings

NASA Astrophysics Data System (ADS)

Azevedo, Thales; Jusinskas, Renann Lipinski

2017-10-01

The sectorized description of the (chiral) heterotic string using pure spinors has been misleadingly viewed as an infinite tension string. One evidence for this fact comes from the tree level 3-point graviton amplitude, which we show to contain the usual Einstein term plus a higher curvature contribution. After reintroducing a dimensionful parameter ℓ in the theory, we demonstrate that the heterotic model is in fact two-fold, depending on the choice of the supersymmetric sector, and that the spectrum also contains one massive (open string like) multiplet. By taking the limit ℓ → ∞, we finally show that the ambitwistor string is recovered, reproducing the unexpected heterotic state in Mason and Skinner's RNS description.

Metastable Bound States of Two-Dimensional Magnetoexcitons in the Lowest Landau Levels Approximation

NASA Astrophysics Data System (ADS)

Moskalenko, S. A.; Khadzhi, P. I.; Podlesny, I. V.; Dumanov, E. V.; Liberman, M. A.; Zubac, I. A.

2017-12-01

The possible existence of the two-dimensional bimagnetoexcitons and metastable bound states formed by two magnetoexcitons with opposite in-plane wave vectors k and -k has been studied. Magnetoexcitons taking part in the formation of molecules look as two electric dipoles with the arms oriented in-plane perpendicular to the respective wave vectors and with the length of the arms d=k(l_0)^2, where l_0 is the magnetic length. Two antiparallel dipoles moving with equal, yet antiparallel, wave vectors have the possibility of moving with equal probability in any direction of the plane, which is determined by the trial wave function of relative motion φ_n(|k|), depending on modulus k. The magnetoexcitons are composed of electrons and holes situated on the lowest Landau levels with the cyclotron energies greater than the binding energy of the 2D Wannier-Mott exciton. The description has been made in Landau gauge. The spin states of two electrons have been chosen in the form of antisymmetric or symmetric combinations with parameter η=+/-1. The effective spins of two heavy holes have been combined in the same resultant spinor states as the spin of the electrons. Because the projections of the both spinor states with η=+/-1 are equal to zero, the influence of the Zeeman splitting effect vanishes. In the case of trial wave function, the maximal density of the magnetoexcitons in the momentum space is concentrated on the in-plane ring. In the approximation of the lowest Landau levels, when the influence of the excited Landau levels is neglected, stable bound states of bimagnetoexcitons do not exist for both spin orientations. Instead, in the case of α=0.5 and η=1, a deep metastable bound state with the activation barrier comparable with two magnetoexciton ionization potentials 2I_l has been revealed. In the case of η=-1 and α=3.4, only a shallow metastable bound state can appear.

Theoretical investigation of gas-surface interactions

NASA Technical Reports Server (NTRS)

Dyall, Kenneth G.

1992-01-01

The investigation into the appearance of intruder states from the negative continuum when some of the two-electron integrals were omitted was completed. The work shows that, provided all integrals involving core contracted functions in an atomic general contraction are included, or that the core functions are radially localized, meaningful results are obtained and intruder states do not appear. In the area of program development, the Dirac-Hartree-Fock (DHF) program for closed-shell polyatomic molecules was extended to permit Kramers-restricted open-shell DHF calculations with one electron in an open shell or one hole in a closed shell, or state-averaged DHF calculations over several particle or hole doublet states. One application of the open-shell code was to the KO molecule. Another major area of program development is the transformation of integrals from the scalar basis in which they are generated to the 2-spinor basis employed in parts of the DHF program, and hence to supermatrix form. Particularly concerning the omission of small component integrals, and with increase in availability of disk space, it is now possible to consider transforming the integrals. The use of ordered integrals, either in the scalar basis or in the 2-spinor basis, would considerably speed up the construction of the Fock matrix, and even more so if supermatrices were constructed. A considerable amount of effort was spent on analyzing the integral ordering and tranformation for the DHF program. The work of assessing the reliability of the relativistic effective core potentials (RECPs) was continued with calculation of the group IV monoxides. The perturbation of the metal atom provided by oxygen is expected to be larger than that provided by hydrogen and thus provide a better test of the qualification of the RECPs. Calculations on some platinum hydrides were carried out at nonrelativistic (NR), perturbation theory (PT) and DHF levels. Reprints of four papers describing this work are included.

Super-BMS3 algebras from {N}=2 flat supergravities

NASA Astrophysics Data System (ADS)

Lodato, Ivano; Merbis, Wout

2016-11-01

We consider two possible flat space limits of three dimensional {N}=(1, 1) AdS supergravity. They differ by how the supercharges are scaled with the AdS radius ℓ: the first limit (democratic) leads to the usual super-Poincaré theory, while a novel `twisted' theory of supergravity stems from the second (despotic) limit. We then propose boundary conditions such that the asymptotic symmetry algebras at null infinity correspond to supersymmetric extensions of the BMS algebras previously derived in connection to non- and ultra-relativistic limits of the {N}=(1, 1) Virasoro algebra in two dimensions. Finally, we study the supersymmetric energy bounds and find the explicit form of the asymptotic and global Killing spinors of supersymmetric solutions in both flat space supergravity theories.

A comparative study of Laplacians and Schroedinger- Lichnerowicz-Weitzenboeck identities in Riemannian and antisymplectic geometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batalin, Igor A.; I.E. Tamm Theory Division, P.N. Lebedev Physics Institute, Russian Academy of Sciences, 53 Leninsky Prospect, Moscow 119991; Bering, Klaus

2009-07-15

We introduce an antisymplectic Dirac operator and antisymplectic gamma matrices. We explore similarities between, on one hand, the Schroedinger-Lichnerowicz formula for spinor bundles in Riemannian spin geometry, which contains a zeroth-order term proportional to the Levi-Civita scalar curvature, and, on the other hand, the nilpotent, Grassmann-odd, second-order {delta} operator in antisymplectic geometry, which, in general, has a zeroth-order term proportional to the odd scalar curvature of an arbitrary antisymplectic and torsion-free connection that is compatible with the measure density. Finally, we discuss the close relationship with the two-loop scalar curvature term in the quantum Hamiltonian for a particle in amore » curved Riemannian space.« less

Rigid supersymmetric backgrounds of 3-dimensional Newton-Cartan supergravity

DOE PAGES

Knodel, Gino; Lisbao, Pedro; Liu, James T.

2016-06-06

Recently, a non-relativistic off-shell formulation of three dimensional Newton-Cartan supergravity was proposed as the c → ∞ limit of three dimensional N = 2 super-gravity [1]. Here in the present paper we study supersymmetric backgrounds within this theory. Using integrability constraints for the non-relativistic Killing spinor equations, we explicitly construct all maximally supersymmetric solutions, which admit four supercharges. In addition to these solutions, there aremore » $$\\frac{1}{2}$$ -BPS solutions with reduced supersymmetry. We give explicit examples of such backgrounds and derive necessary conditions for backgrounds preserving two supercharges. Finally, we address how supersymmetric backgrounds of N = 2 supergravity are connected to the solutions found here in the c → ∞ limit.« less

AdS6 solutions of type II supergravity

NASA Astrophysics Data System (ADS)

Apruzzi, Fabio; Fazzi, Marco; Passias, Achilleas; Rosa, Dario; Tomasiello, Alessandro

2014-11-01

Very few AdS6 × M 4 supersymmetric solutions are known: one in massive IIA, and two IIB solutions dual to it. The IIA solution is known to be unique; in this paper, we use the pure spinor approach to give a classification for IIB supergravity. We reduce the problem to two PDEs on a two-dimensional space Σ. M 4 is then a fibration of S 2 over Σ; the metric and fluxes are completely determined in terms of the solution to the PDEs. The results seem likely to accommodate near-horizon limits of ( p, q)-fivebrane webs studied in the literature as a source of CFT5's. We also show that there are no AdS6 solutions in eleven-dimensional supergravity.

Twistor Geometry of Null Foliations in Complex Euclidean Space

NASA Astrophysics Data System (ADS)

Taghavi-Chabert, Arman

2017-01-01

We give a detailed account of the geometric correspondence between a smooth complex projective quadric hypersurface Q^n of dimension n ≥ 3, and its twistor space PT, defined to be the space of all linear subspaces of maximal dimension of Q^n. Viewing complex Euclidean space CE^n as a dense open subset of Q^n, we show how local foliations tangent to certain integrable holomorphic totally null distributions of maximal rank on CE^n can be constructed in terms of complex submanifolds of PT. The construction is illustrated by means of two examples, one involving conformal Killing spinors, the other, conformal Killing-Yano 2-forms. We focus on the odd-dimensional case, and we treat the even-dimensional case only tangentially for comparison.

Comment on “Approximate solutions of the Dirac equation for the Rosen-Morse potential including the spin-orbit centrifugal term” [J. Math. Phys. 51, 023525 (2010)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghoumaid, A.; Benamira, F.; Guechi, L.

2016-02-15

It is shown that the application of the Nikiforov-Uvarov method by Ikhdair for solving the Dirac equation with the radial Rosen-Morse potential plus the spin-orbit centrifugal term is inadequate because the required conditions are not satisfied. The energy spectra given is incorrect and the wave functions are not physically acceptable. We clarify the problem and prove that the spinor wave functions are expressed in terms of the generalized hypergeometric functions {sub 2}F{sub 1}(a, b, c; z). The energy eigenvalues for the bound states are given by the solution of a transcendental equation involving the hypergeometric function.

Exact results in 3d N = 2 Spin(7) gauge theories with vector and spinor matters

NASA Astrophysics Data System (ADS)

Nii, Keita

2018-05-01

We study three-dimensional N = 2 Spin(7) gauge theories with N S spinorial matters and with N f vectorial matters. The quantum Coulomb branch on the moduli space of vacua is one- or two-dimensional depending on the matter contents. For particular values of ( N f , N S ), we find s-confinement phases and derive exact superpotentials. The 3d dynamics of Spin(7) is connected to the 4d dynamics via KK-monopoles. Along the Higgs branch of the Spin(7) theories, we obtain 3d N = 2 G 2 or SU(4) theories and some of them lead to new s-confinement phases. As a check of our analysis we compute superconformal indices for these theories.

General relation between the group delay and dwell time in multicomponent electron systems

NASA Astrophysics Data System (ADS)

Zhai, Feng; Lu, Junqiang

2016-10-01

For multicomponent electron scattering states, we derive a general relation between the Wigner group delay and the Bohmian dwell time. It is found that the definition of group delay should account for the phase of the spinor wave functions of propagating modes. The difference between the group delay and dwell time comes from both the interference delay and the decaying modes. For barrier tunneling of helical electrons on a surface of topological insulators, our calculations including the trigonal-warping term show that the decaying modes can contribute greatly to the group delay. The derived relation between the group delay and the dwell time is helpful to unify the two definitions of tunneling time in a quite general situation.

Beam splitter phase shifts: Wave optics approach

NASA Astrophysics Data System (ADS)

Agnesi, Antonio; Degiorgio, Vittorio

2017-10-01

We investigate the phase relationships between transmitted and reflected waves in a lossless beam splitter having a multilayer structure, using the matrix approach as outlined in classical optics books. Contrarily to the case of the quantum optics formalism generally employed to describe beam splitters, these matrices are not unitary. In this note we point out the existence of general relations among the elements of the transfer matrix that describes the multilayer beam splitter. Such relations, which are independent of the detailed structure of the beam splitter, fix the phase shifts between reflected and transmitted waves. It is instructive to see how the results obtained by Zeilinger by using spinor algebra and Pauli matrices can be easily derived from our general relations.

Boundary conditions and transmission reflection of electron spin in a quantum well

NASA Astrophysics Data System (ADS)

Dargys, A.

2012-04-01

Boundary conditions for a spinor at the interface of hetero- and homobarrier in the presence of spin-orbit interaction are briefly reviewed and generalized. Then they are applied to 2D electron in the presence of a discontinuity of physical parameters in a quantum well. It is shown that in general case under oblique electron incidence, the problem can be solved analytically and the Fresnel-type formulae for polarization can be obtained if, in addition, the Gröbner basis algorithm is addressed to solve the problem. It is observed that the transmitted and reflected spin polarization may strongly depend on values of spin-orbit constants on both sides of the homobarrier in the quantum well.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ayala, Alejandro; Hentschinski, Martin; Jalilian-Marian, Jamal

Azimuthal angular correlations between produced hadrons/jets in high energy collisions are a sensitive probe of the dynamics of QCD at small x. Here we derive the triple differential cross section for inclusive production of 3 polarized partons in DIS at small x using the spinor helicity formalism. The target proton or nucleus is described using the Color Glass Condensate (CGC) formalism. The resulting expressions are used to study azimuthal angular correlations between produced partons in order to probe the gluon structure of the target hadron or nucleus. Finally, our analytic expressions can also be used to calculate the real partmore » of the Next to Leading Order (NLO) corrections to di-hadron production in DIS by integrating out one of the three final state partons.« less

Particlelike solutions of the Einstein-Dirac equations

NASA Astrophysics Data System (ADS)

Finster, Felix; Smoller, Joel; Yau, Shing-Tung

1999-05-01

The coupled Einstein-Dirac equations for a static, spherically symmetric system of two fermions in a singlet spinor state are derived. Using numerical methods, we construct an infinite number of solitonlike solutions of these equations. The stability of the solutions is analyzed. For weak coupling (i.e., small rest mass of the fermions), all the solutions are linearly stable (with respect to spherically symmetric perturbations), whereas for stronger coupling, both stable and unstable solutions exist. For the physical interpretation, we discuss how the energy of the fermions and the (ADM) mass behave as functions of the rest mass of the fermions. Although gravitation is not renormalizable, our solutions of the Einstein-Dirac equations are regular and well behaved even for strong coupling.

Spin formalism and applications to new physics searches

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haber, H.E.

1994-12-01

An introduction to spin techniques in particle physics is given. Among the topics covered are: helicity formalism and its applications to the decay and scattering of spin-1/2 and spin-1 particles, techniques for evaluating helicity amplitudes (including projection operator methods and the spinor helicity method), and density matrix techniques. The utility of polarization and spin correlations for untangling new physics beyond the Standard Model at future colliders such as the LHC and a high energy e{sup +}e{sup {minus}} linear collider is then considered. A number of detailed examples are explored including the search for low-energy supersymmetry, a non-minimal Higgs boson sector,more » and new gauge bosons beyond the W{sup {+-}} and Z.« less

Quantum dynamics of relativistic bosons through nonminimal vector square potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliveira, Luiz P. de, E-mail: oliveira.phys@gmail.com

The dynamics of relativistic bosons (scalar and vectorial) through nonminimal vector square (well and barrier) potentials is studied in the Duffin–Kemmer–Petiau (DKP) formalism. We show that the problem can be mapped in effective Schrödinger equations for a component of the DKP spinor. An oscillatory transmission coefficient is found and there is total reflection. Additionally, the energy spectrum of bound states is obtained and reveals the Schiff–Snyder–Weinberg effect, for specific conditions the potential lodges bound states of particles and antiparticles. - Highlights: • DKP bosons in a nonminimal vector square potential are studied. • Spin zero and spin one bosons havemore » the same results. • The Schiff–Snyder–Weinberg effect is observed.« less

Fierz bilinear formulation of the Maxwell-Dirac equations and symmetry reductions

NASA Astrophysics Data System (ADS)

Inglis, Shaun; Jarvis, Peter

2014-09-01

We study the Maxwell-Dirac equations in a manifestly gauge invariant presentation using only the spinor bilinear scalar and pseudoscalar densities, and the vector and pseudovector currents, together with their quadratic Fierz relations. The internally produced vector potential is expressed via algebraic manipulation of the Dirac equation, as a rational function of the Fierz bilinears and first derivatives (valid on the support of the scalar density), which allows a gauge invariant vector potential to be defined. This leads to a Fierz bilinear formulation of the Maxwell tensor and of the Maxwell-Dirac equations, without any reference to gauge dependent quantities. We show how demanding invariance of tensor fields under the action of a fixed (but arbitrary) Lie subgroup of the Poincaré group leads to symmetry reduced equations. The procedure is illustrated, and the reduced equations worked out explicitly for standard spherical and cylindrical cases, which are coupled third order nonlinear PDEs. Spherical symmetry necessitates the existence of magnetic monopoles, which do not affect the coupled Maxwell-Dirac system due to magnetic terms cancelling. In this paper we do not take up numerical computations. As a demonstration of the power of our approach, we also work out the symmetry reduced equations for two distinct classes of dimension 4 one-parameter families of Poincaré subgroups, one splitting and one non-splitting. The splitting class yields no solutions, whereas for the non-splitting class we find a family of formal exact solutions in closed form.

Spacetime and gravitation.

NASA Astrophysics Data System (ADS)

Kopczyński, W.; Trautman, A.

This book is a revised translation of the Polish original "Czasoprzestrzeń i grawitacja", Warszawa (Poland), Państwowe Wydawnictwo Naukowe, 1984. Ideas about space and time are at the root of one's understanding of nature, both at the intuitive level of everyday experience and in the framework of sophisticated physical theories. These ideas have led to the development of geometry and its applications to physics. The contemporary physical theory of space and time, including its extention to the phenomena of gravitation, is Einstein's theory of relativity. The book is a short introduction to this theory. A great deal of emphasis is given to the geometrical aspects of relativity theory and its comparison with the Newtonian view of the world. There are short chapters on the origins of Einstein's theory, gravitational waves, cosmology, spinors and the Einstein-Cartan theory.

Leading multi-soft limits from scattering equations

NASA Astrophysics Data System (ADS)

Zlotnikov, Michael

2017-10-01

A Cachazo-He-Yuan (CHY) type formula is derived for the leading gluon, bi-adjoint scalar ϕ 3, Yang-Mills-scalar and non-linear sigma model m-soft factors S m in arbitrary dimension. The general formula is used to evaluate explicit examples for up to three soft legs analytically and up to four soft legs numerically via comparison with amplitude ratios under soft kinematics. A structural pattern for gluon m-soft factor is inferred and a simpler formula for its calculation is conjectured. In four dimensions, a Cachazo-Svrček-Witten (CSW) recursive procedure producing the leading m-soft gluon factor in spinor helicity formalism is developed as an alternative, and Britto-Cachazo-Feng-Witten (BCFW) recursion is used to obtain the leading four-soft gluon factor for all analytically distinct helicity configurations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Junjun; Feng, Tongtong; Gu, Qiang, E-mail: qgu@ustb.edu.cn

Understanding the collective dynamics in a many-body system has been a central task in condensed matter physics. To achieve this task, we develop a Hartree–Fock theory to study the collective oscillations of spinor Fermi system, motivated by recent experiment on spin-9/2 fermions. We observe an oscillation period shoulder for small rotation angles. Different from previous studies, where the shoulder is found connected to the resonance from periodic to running phase, here the system is always in a running phase in the two-body phase space. This shoulder survives even in the many-body oscillations, which could be tested in the experiments. Wemore » also show how these collective oscillations evolve from two- to many-body. Our theory provides an alternative way to understand the collective dynamics in large-spin Fermi systems.« less

Quadratic response functions in the relativistic four-component Kohn-Sham approximation

NASA Astrophysics Data System (ADS)

Henriksson, Johan; Saue, Trond; Norman, Patrick

2008-01-01

A formulation and implementation of the quadratic response function in the adiabatic four-component Kohn-Sham approximation is presented. The noninteracting reference state is time-reversal symmetric and formed from Kramers pair spinors, and the energy density is gradient corrected. Example calculations are presented for the optical properties of disubstituted halobenzenes in their meta and ortho conformations. It is demonstrated that correlation and relativistic effects are not additive, and it is shown that relativity alone reduces the μβ¯-response signal by 62% and 75% for meta- and ortho-bromobenzene, respectively, and enhances the same response by 17% and 21% for meta- and ortho-iodobenzene, respectively. Of the employed functionals, CAM-B3LYP shows the best performance and gives hyperpolarizabilities β distinctly different from B3LYP.

Majorana Fermions in Particle Physics, Solid State and Quantum Information

NASA Astrophysics Data System (ADS)

Borsten, L.; Duff, M. J.

This review is based on lectures given by M. J. Duff summarising the far reaching contributions of Ettore Majorana to fundamental physics, with special focus on Majorana fermions in all their guises. The theoretical discovery of the eponymous fcrmion in 1937 has since had profound implications for particlc physics, solid state and quantum computation. The breadth of these disciplines is testimony to Majorana's genius, which continues to permeate physics today. These lectures offer a whistle-stop tour through some limited subset of the key ideas. In addition to touching on these various applications, we will draw out some fascinating relations connecting the normed division algebras R, ℂ, H, O to spinors, trialities. K-theory and the classification of stable topological states of symmetry-protected gapped free-fermion systems.

Quantum strain sensor with a topological insulator HgTe quantum dot

PubMed Central

Korkusinski, Marek; Hawrylak, Pawel

2014-01-01

We present a theory of electronic properties of HgTe quantum dot and propose a strain sensor based on a strain-driven transition from a HgTe quantum dot with inverted bandstructure and robust topologically protected quantum edge states to a normal state without edge states in the energy gap. The presence or absence of edge states leads to large on/off ratio of conductivity across the quantum dot, tunable by adjusting the number of conduction channels in the source-drain voltage window. The electronic properties of a HgTe quantum dot as a function of size and applied strain are described using eight-band Luttinger and Bir-Pikus Hamiltonians, with surface states identified with chirality of Luttinger spinors and obtained through extensive numerical diagonalization of the Hamiltonian. PMID:24811674

Knots in electromagnetism

NASA Astrophysics Data System (ADS)

Arrayás, M.; Bouwmeester, D.; Trueba, J. L.

2017-01-01

Maxwell equations in vacuum allow for solutions with a non-trivial topology in the electric and magnetic field line configurations at any given moment in time. One example is a space filling congruence of electric and magnetic field lines forming circles lying on the surfaces of nested tori. In this example the electric, magnetic and Poynting vector fields are orthogonal everywhere. As time evolves the electric and magnetic fields expand and deform without changing the topology and energy, while the Poynting vector structure remains unchanged while propagating with the speed of light. The topology is characterized by the concept of helicity of the field configuration. Helicity is an important fundamental concept and for massless fields it is a conserved quantity under conformal transformations. We will review several methods by which linked and knotted electromagnetic (spin-1) fields can be derived. A first method, introduced by A. Rañada, uses the formulation of the Maxwell equations in terms of differential forms combined with the Hopf map from the three-sphere S3 to the two-sphere S2. A second method is based on spinor and twistor theory developed by R. Penrose in which elementary twistor functions correspond to the family of electromagnetic torus knots. A third method uses the Bateman construction of generating null solutions from complex Euler potentials. And a fourth method uses special conformal transformations, in particular conformal inversion, to generate new linked and knotted field configurations from existing ones. This fourth method is often accompanied by shifting singularities in the field to complex space-time points. Of course the various methods must be closely related to one another although they have been developed largely independently and they suggest different directions in which to expand the study of topologically non-trivial field configurations. It will be shown how the twistor formulation allows for a direct extension to massless fields of other spin values, such as spin-2 fields satisfying the linearized Einstein vacuum equation, and how the formulation by A. Rañada can be extended to fields for which the electric and magnetic fields are not orthogonal everywhere. Underlying the various methods is the fact that electric and magnetic field lines can be described as the level curves of complex functions. Compactification of R3 naturally leads to finite energy solutions because the fields at infinity in all directions should all converge towards zero. An intriguing question that is raised by the finite energy is whether there is a connection to the quantization of the classical electromagnetic field. We will review some issues related to this question. Another interesting question is why the general formulation of topologically non-trivial solutions uses the electric and magnetic fields instead of the electromagnetic vector potentials. This leads to a discussion of the Clebsch representation of the electromagnetic field strength 2-form. Finally, a topic of great interest is the possibility of experimentally generating and investigating linked and knotted field configurations. Since the non-trivial topological field solutions exploit the special conformal symmetry of the underlying vacuum wave-equations it will only be possible to approximate the solutions in an experiment, which necessarily introduces material objects that will break the special conformal symmetry. We will review the research on plasma configurations in which the magnetic field-line configuration approximates plasma torus knots leading to the prediction of topological solitons in plasma.

Fierz bilinear formulation of the Maxwell–Dirac equations and symmetry reductions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inglis, Shaun, E-mail: sminglis@utas.edu.au; Jarvis, Peter, E-mail: Peter.Jarvis@utas.edu.au

We study the Maxwell–Dirac equations in a manifestly gauge invariant presentation using only the spinor bilinear scalar and pseudoscalar densities, and the vector and pseudovector currents, together with their quadratic Fierz relations. The internally produced vector potential is expressed via algebraic manipulation of the Dirac equation, as a rational function of the Fierz bilinears and first derivatives (valid on the support of the scalar density), which allows a gauge invariant vector potential to be defined. This leads to a Fierz bilinear formulation of the Maxwell tensor and of the Maxwell–Dirac equations, without any reference to gauge dependent quantities. We showmore » how demanding invariance of tensor fields under the action of a fixed (but arbitrary) Lie subgroup of the Poincaré group leads to symmetry reduced equations. The procedure is illustrated, and the reduced equations worked out explicitly for standard spherical and cylindrical cases, which are coupled third order nonlinear PDEs. Spherical symmetry necessitates the existence of magnetic monopoles, which do not affect the coupled Maxwell–Dirac system due to magnetic terms cancelling. In this paper we do not take up numerical computations. As a demonstration of the power of our approach, we also work out the symmetry reduced equations for two distinct classes of dimension 4 one-parameter families of Poincaré subgroups, one splitting and one non-splitting. The splitting class yields no solutions, whereas for the non-splitting class we find a family of formal exact solutions in closed form. - Highlights: • Maxwell–Dirac equations derived in manifestly gauge invariant tensor form. • Invariant scalar and four vector fields for four Poincaré subgroups derived, including two unusual cases. • Symmetry reduction imposed on Maxwell–Dirac equations under example subgroups. • Magnetic monopole arises for spherically symmetric case, consistent with charge quantization condition.« less

Brownian Motion and its Conditional Descendants

NASA Astrophysics Data System (ADS)

Garbaczewski, Piotr

It happened before [1] that I have concluded my publication with a special dedication to John R. Klauder. Then, the reason was John's PhD thesis [2] and the questions (perhaps outdated in the eyes of the band-wagon jumpers, albeit still retaining their full vitality [3]): (i) What are the uses of the classical (c-number, non-Grassmann) spinor fields, especially nonlinear ones, what are they for at all ? (ii) What are, if any, the classical partners for Fermi models and fields in particular ? The present dedication, even if not as conspicuously motivated as the previous one by John's research, nevertheless pertains to investigations pursued by John through the years and devoted to the analysis of random noise. Sometimes, re-reading old papers and re-analysing old, frequently forgotten ideas might prove more rewarding than racing the fashions. Following this attitude, let us take as the departure point Schrödinger's original suggestion [4] of the existence of a special class of random processes, which have their origin in the Einstein-Smoluchowski theory of the Brownian motion and its Wiener's codification. The original analysis due to Schrodinger of the probabilistic significance of the heat equation and of its time adjoint in parallel, remained unnoticed by the physics community, and since then forgotten. It reappeared however in the mathematical literature as an inspiration to generalise the concept of Markovian diffusions to the case of Bernstein stochastic processes. But, it stayed without consequences for a deeper understanding of the possible physical phenomena which might underly the corresponding abstract formalism. Schrödinger's objective was to initiate investigations of possible links between quantum theory and the theory of Brownian motion, an attempt which culminated later in the so-called Nelson's stochastic mechanics [8] and its encompassing formalism [7] in which the issue of the Brownian implementation of quantum dynamics is placed in the framework of Markov-Bernstein diffusions…

Lorentz quantum mechanics

NASA Astrophysics Data System (ADS)

Zhang, Qi; Wu, Biao

2018-01-01

We present a theoretical framework for the dynamics of bosonic Bogoliubov quasiparticles. We call it Lorentz quantum mechanics because the dynamics is a continuous complex Lorentz transformation in complex Minkowski space. In contrast, in usual quantum mechanics, the dynamics is the unitary transformation in Hilbert space. In our Lorentz quantum mechanics, three types of state exist: space-like, light-like and time-like. Fundamental aspects are explored in parallel to the usual quantum mechanics, such as a matrix form of a Lorentz transformation, and the construction of Pauli-like matrices for spinors. We also investigate the adiabatic evolution in these mechanics, as well as the associated Berry curvature and Chern number. Three typical physical systems, where bosonic Bogoliubov quasi-particles and their Lorentz quantum dynamics can arise, are presented. They are a one-dimensional fermion gas, Bose-Einstein condensate (or superfluid), and one-dimensional antiferromagnet.

Projective flatness in the quantisation of bosons and fermions

NASA Astrophysics Data System (ADS)

Wu, Siye

2015-07-01

We compare the quantisation of linear systems of bosons and fermions. We recall the appearance of projectively flat connection and results on parallel transport in the quantisation of bosons. We then discuss pre-quantisation and quantisation of fermions using the calculus of fermionic variables. We define a natural connection on the bundle of Hilbert spaces and show that it is projectively flat. This identifies, up to a phase, equivalent spinor representations constructed by various polarisations. We introduce the concept of metaplectic correction for fermions and show that the bundle of corrected Hilbert spaces is naturally flat. We then show that the parallel transport in the bundle of Hilbert spaces along a geodesic is a rescaled projection provided that the geodesic lies within the complement of a cut locus. Finally, we study the bundle of Hilbert spaces when there is a symmetry.

J dependence in the LSDA+U treatment of noncollinear magnets

NASA Astrophysics Data System (ADS)

Bousquet, Eric; Spaldin, Nicola

2010-12-01

We re-examine the commonly used density-functional theory plus Hubbard U (DFT+U) method for the case of noncollinear magnets. While many studies neglect to explicitly include the exchange-correction parameter J , or consider its exact value to be unimportant, here we show that in the case of noncollinear magnetism calculations the J parameter can strongly affect the magnetic ground state. We illustrate the strong J dependence of magnetic canting and magnetocrystalline anisotropy by calculating trends in the magnetic lithium orthophosphate family LiMPO4 ( M=Fe and Ni) and difluorite family MF2 ( M=Mn , Fe, Co, and Ni). Our results can be readily understood by expanding the usual DFT+U equations within the spinor scheme, in which the J parameter acts directly on the off-diagonal components which determine the spin canting.

Implications of Neutrino Oscillations on the Dark-Matter World

NASA Astrophysics Data System (ADS)

Hwang, W.-Y. Pauchy

2014-01-01

According to my own belief that "The God wouldn't create a world that is so boring that a particle knows only the very feeble weak interaction.", maybe we underestimate the roles of neutrinos. We note that right-handed neutrinos play no roles, or don't exist, in the minimal Standard Model. We discuss the language to write down an extended Standard Model - using renormalizable quantum field theory as the language; to start with a certain set of basic units under a certain gauge group; in fact, to use the three right-handed neutrinos to initiate the family gauge group SUf (3). Specifically we use the left-handed and right-handed spinors to form the basic units together with SUc (3) × SUL (2) × U (1) × SUf (3) as the gauge group. The dark-matter SUf (3) world couples with the lepton world, but not with the quark world. Amazingly enough, the space of the Standard-Model Higgs Φ (1 , 2), the family Higgs triplet Φ(3, 1), and the neutral part of the mixed family Higgs Φ0 (3 , 2) undergoes the spontaneous symmetry breaking, i.e. the Standard-Model Higgs mechanism and the "project-out" family Higgs mechanism, to give rise to the weak bosons W± and Z0, one Standard-Model Higgs, the eight massive family gauge bosons, and the remaining four massive neutral family Higgs particles, and nothing more. Thus, the roles of neutrinos in this extended Standard Model are extremely interesting in connection with the dark-matter world.

A theory with consolidation: Linking everything to explain everything

NASA Astrophysics Data System (ADS)

Biraris, Gaurav Shantaram

The paper reports a theory which gives explicit (ontic) understanding of the abstract (epistemic) mechanisms spanning many branches of physics. It results to most modern physics starting from Newtonian physics by abandoning progress in twentieth century. The theory assumes consolidation of points in 4-balls of specific radius in the universe. Thus the 4-balls are fundamental elements of the universe. Analogue of momentum defined as soul vector is assumed to be induced on the 4-balls at the beginning of the universe. Then with progression of local time, collisions happen leading to different rotations of CNs. For such rotations, the consolidation provides centripetal binding. By using general terminologies of force and work, the mass energy mechanism gets revealed. The theory provides explicit interpretation of intrinsic properties of mass, electric charge, color charge, weak charge, spin etc. It also provides explicit understanding of the wave-particle duality & quantum mechanics. Epistemic study of the universe with the consolidation results to conventional quantum theories. Elementary mechanism of the field interactions is evident due to conservation of the soul vectors, and its epistemic expectation results to the gauge theories. The theory predicts that four types of interaction would exist in the universe along with the acceptable relative strengths; it provides fundamental interpretation of the physical forces. Further, it explains the basic mechanisms which can be identified with dark energy & dark matter. It also results to (or explains) entanglement, chirality, excess of matter, 4-component spinor, real-abstract (ontic-epistemic) correspondence etc. The theory is beyond standard model and results to the standard model, relativity, dark energy & dark matter, starting by simple assumptions.

Origin of families of fermions and their mass matrices

NASA Astrophysics Data System (ADS)

Bračič, A. Borštnik; Borštnik, N. S. Mankoč

2006-10-01

We are proposing a new way of describing families of quarks and leptons, using the approach unifying all the internal degrees of freedom, proposed by one of us [N. Mankoč Borštnik, Phys. Lett. B 292, 25 (1992).PYLBAJ0370-269310.1016/0370-2693(92)90603-2][N. Mankoč-Borštnik, J. Math. Phys. (N.Y.)JMAPAQ0022-2488 34, 3731 (1993).10.1063/1.530055][N. Mankoč Borštnik, J. Math. Phys. (N.Y.)JMAPAQ0022-2488 36, 1593 (1995).10.1063/1.531071][N. S. Mankoč Borštnik, Mod. Phys. Lett. AMPLAEQ0217-7323 10, 587 (1995).10.1142/S0217732395000624][N. S. Mankoč Borštnik and S. Fajfer, Nuovo Cimento Soc. Ital. Fis. BNIFBAP0369-4100 112, 1637 (1997).][A. Borštnik and N. S. Mankoč Borštnik, in Proceedings to the International Workshop on “What Comes Beyond the Standard Model, Bled, Slovenia, 1998, edited by N. Mankoč Borštnik, H. B. Nielsen, and C. Froggatt (DMFA, Založništvo, 1999), p. 52.][N. S. Mankoč Borštnik and H. B. Nielsen, Phys. Rev. 62, 04010 (2000).PHRVAO0031-899X][N. S. Mankoč Borštnik, Int. J. Theor. Phys. 40, 315 (2001), and references therein.IJTPBM0020-774810.1023/A:1003708032726][A. Borštnik and N. S. Mankoč Borštnik, in Proceedings to the International Workshop on “What Comes Beyond the Standard Model”, Bled 2000, 2001, 2002 Volume 2, edited by N. Mankoč Borštnik, H. B. Nielsen, C. Froggatt, and D. Lukman (DMFA, Založništvo, 2002), p. 27 and the paper (unpublished).][A. Borštnik and N. S. Mankoč Borštnik, in Proceedings to the Euroconference on Symmetries Beyond the Standard Model, Portorož, 2003 edited by N. Mankoč Borštnik, H. B. Nielsen, C. Froggatt, and D. Lukman (DMFA, Založništvo, 2003), pp. 27 51.]. Spinors, living in d(=1+13)-dimensional space, carry in this approach only the spin and interact with only the gravity through vielbeins and two kinds of the spin connection fields—the gauge fields of the Poincaré group (pa,Sab) and the second kind of the Clifford algebra objects (S˜ab). All the quarks and the leptons of one family appear in one Weyl representation of a chosen handedness of the Lorentz group, if analyzed with respect to the standard model gauge groups, which are subgroups of the group SO(1,13): the right handed (with respect to SO(1,3)) weak chargeless quarks and leptons and the left handed weak charged quarks and leptons (with the right handed neutrino included). A part of the starting Lagrange density of a Weyl spinor in d=1+13 transforms right handed quarks and leptons into left handed quarks and leptons manifesting as the Yukawa couplings of the standard model. A kind of the Clifford algebra objects generates families of quarks and leptons and contributes to diagonal and off-diagonal Yukawa couplings. The approach predicts an even number of families, treating leptons and quarks equivalently (we do not study a possible appearance of Majorana fermions yet). In this paper we investigate within this approach the appearance of the Yukawa couplings within one family of quarks and leptons as well as among the families (without assuming any Higgs fields like in the standard model). We present the mass matrices for four families and investigate whether our way of generating families might explain the origin of families of quarks and leptons as well as their observed properties—the masses and the mixing matrices. Numerical results are presented in Ref. [M. Breskvar, D. Lukman, and N. S. Mankoč Borštnik, hep-ph/0606159.].

BOOK REVIEW: Modern Supersymmetry

NASA Astrophysics Data System (ADS)

Kulish, Petr P.

2006-12-01

We have spent more than twenty years applying supersymmetry (SUSY) to elementary particle physics and attempting to find an experimental manifestation of this symmetry. Terning's monograph demonstrates the strong influence of SUSY on theoretical elaborations in the field of elementary particles. It gives both an overview of modern supersymmetry in elementary particle physics and calculation techniques. The author, trying to be closer to applications of SUSY in the real world of elementary particles, is also anticipating the importance of supersymmetry for rigorous study of nonperturbative phenomena in quantum field theory. In particular, he presents the `exact' SUSY β function using instanton methods, phenomena of anomalies and dualities. Supersymmetry algebra is introduced by adding two anticommuting spinor generators to Poincaré algebra and by presenting massive and massless supermultiplets of its representations. The author prefers to use mostly the component description of field contents of the theories in question rather than the superfield formalism. Such a style makes the account closer to physical chartacteristics. Relations required by SUSY among β functions of the gauge, Yukawa and quartic interactions are checked by direct calculations as well as to all orders in perturbation theory, thus demonstrating that SUSY survives quantization. A discussion is included of the hierarchy problem of different scales of weak and strong interactions and its possible solution by the minimal supersymmetric standard model. Different SUSY breaking mechanisms are presented corresponding to a realistic phenomenology. The monograph can also be considered as a guide to `duality' relations connecting different SUSY gauge theories, supergravities and superstrings. This is demonstrated referring to the particular properties and characteristics of these theories (field contents, scaling dimensions of appropriate operators etc). In particular, the last chapter deals with the AdS/CFT correspondence. The author explains clearly most of the arguments in discussions and refers for further details to original papers (with corresponding arXiv numbers), selected lists of which appear at the end of each chapter (there are more than 300 references in the book). Considered as a whole the book covers primers on quantum fields, Feynman diagrams, renormalization procedure and renormalization groups, as well as the representation theory of classical linear Lie algebras. Some necessary information on irreducible representations of su(N), so(N) and sp(2N) is given in an appendix. There are in the text short historical and biographical notes concerning those scientists who made important contributions to the subject of the monograph: S Coleman, Yu Golfand, E Witten and others. Most of the seventeen chapters contain a few exercises to check the reader's understanding of the corresponding material. This monograph will be useful for graduate students and researchers in the field of elementary particles.

Three-Component Soliton States in Spinor F =1 Bose-Einstein Condensates

NASA Astrophysics Data System (ADS)

Bersano, T. M.; Gokhroo, V.; Khamehchi, M. A.; D'Ambroise, J.; Frantzeskakis, D. J.; Engels, P.; Kevrekidis, P. G.

2018-02-01

Dilute-gas Bose-Einstein condensates are an exceptionally versatile test bed for the investigation of novel solitonic structures. While matter-wave solitons in one- and two-component systems have been the focus of intense research efforts, an extension to three components has never been attempted in experiments. Here, we experimentally demonstrate the existence of robust dark-bright-bright (DBB) and dark-dark-bright solitons in a multicomponent F =1 condensate. We observe lifetimes on the order of hundreds of milliseconds for these structures. Our theoretical analysis, based on a multiscale expansion method, shows that small-amplitude solitons of these types obey universal long-short wave resonant interaction models, namely, Yajima-Oikawa systems. Our experimental and analytical findings are corroborated by direct numerical simulations highlighting the persistence of, e.g., the DBB soliton states, as well as their robust oscillations in the trap.

Three-Component Soliton States in Spinor F=1 Bose-Einstein Condensates.

PubMed

Bersano, T M; Gokhroo, V; Khamehchi, M A; D'Ambroise, J; Frantzeskakis, D J; Engels, P; Kevrekidis, P G

2018-02-09

Dilute-gas Bose-Einstein condensates are an exceptionally versatile test bed for the investigation of novel solitonic structures. While matter-wave solitons in one- and two-component systems have been the focus of intense research efforts, an extension to three components has never been attempted in experiments. Here, we experimentally demonstrate the existence of robust dark-bright-bright (DBB) and dark-dark-bright solitons in a multicomponent F=1 condensate. We observe lifetimes on the order of hundreds of milliseconds for these structures. Our theoretical analysis, based on a multiscale expansion method, shows that small-amplitude solitons of these types obey universal long-short wave resonant interaction models, namely, Yajima-Oikawa systems. Our experimental and analytical findings are corroborated by direct numerical simulations highlighting the persistence of, e.g., the DBB soliton states, as well as their robust oscillations in the trap.

Interferometric sensitivity and entanglement by scanning through quantum phase transitions in spinor Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Feldmann, P.; Gessner, M.; Gabbrielli, M.; Klempt, C.; Santos, L.; Pezzè, L.; Smerzi, A.

2018-03-01

Recent experiments demonstrated the generation of entanglement by quasiadiabatically driving through quantum phase transitions of a ferromagnetic spin-1 Bose-Einstein condensate in the presence of a tunable quadratic Zeeman shift. We analyze, in terms of the Fisher information, the interferometric value of the entanglement accessible by this approach. In addition to the Twin-Fock phase studied experimentally, we unveil a second regime, in the broken axisymmetry phase, which provides Heisenberg scaling of the quantum Fisher information and can be reached on shorter time scales. We identify optimal unitary transformations and an experimentally feasible optimal measurement prescription that maximize the interferometric sensitivity. We further ascertain that the Fisher information is robust with respect to nonadiabaticity and measurement noise. Finally, we show that the quasiadiabatic entanglement preparation schemes admit higher sensitivities than dynamical methods based on fast quenches.

A Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies

NASA Astrophysics Data System (ADS)

Lu, Wei

2017-09-01

We propose a Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies in the context of composite Higgs bosons. Standard model fermions are represented by algebraic spinors of six-dimensional binary Clifford algebra, while ternary Clifford algebra-related flavor projection operators control allowable flavor-mixing interactions. There are three composite electroweak Higgs bosons resulted from top quark, tau neutrino, and tau lepton condensations. Each of the three condensations gives rise to masses of four different fermions. The fermion mass hierarchies within these three groups are determined by four-fermion condensations, which break two global chiral symmetries. The four-fermion condensations induce axion-like pseudo-Nambu-Goldstone bosons and can be dark matter candidates. In addition to the 125 GeV Higgs boson observed at the Large Hadron Collider, we anticipate detection of tau neutrino composite Higgs boson via the charm quark decay channel.

Core structure and dynamics of non-Abelian vortices in a biaxial nematic spinor Bose-Einstein condensate

NASA Astrophysics Data System (ADS)

Borgh, Magnus O.; Ruostekoski, Janne

2016-05-01

We demonstrate that multiple interaction-dependent defect core structures as well as dynamics of non-Abelian vortices can be realized in the biaxial nematic (BN) phase of a spin-2 atomic Bose-Einstein condensate (BEC). An experimentally simple protocol may be used to break degeneracy with the uniaxial nematic phase. We show that a discrete spin-space symmetry in the core may be reflected in a breaking of its spatial symmetry. The discrete symmetry of the BN order parameter leads to non-commuting vortex charges. We numerically simulate reconnection of non-Abelian vortices, demonstrating formation of the obligatory rung vortex. In addition to atomic BECs, non-Abelian vortices are theorized in, e.g., liquid crystals and cosmic strings. Our results suggest the BN spin-2 BEC as a prime candidate for their realization. We acknowledge financial support from the EPSRC.

Phase magnification by two-axis countertwisting for detection-noise robust interferometry

NASA Astrophysics Data System (ADS)

Anders, Fabian; Pezzè, Luca; Smerzi, Augusto; Klempt, Carsten

2018-04-01

Entanglement-enhanced atom interferometry has the potential of surpassing the standard quantum limit and eventually reaching the ultimate Heisenberg bound. The experimental progress is, however, hindered by various technical noise sources, including the noise in the detection of the output quantum state. The influence of detection noise can be largely overcome by exploiting echo schemes, where the entanglement-generating interaction is repeated after the interferometer sequence. Here, we propose an echo protocol that uses two-axis countertwisting as the main nonlinear interaction. We demonstrate that the scheme is robust to detection noise and its performance is superior compared to the already demonstrated one-axis twisting echo scheme. In particular, the sensitivity maintains the Heisenberg scaling in the limit of a large particle number. Finally, we show that the protocol can be implemented with spinor Bose-Einstein condensates. Our results thus outline a realistic approach to mitigate the detection noise in quantum-enhanced interferometry.

Searching for Supersolidity in Ultracold Atomic Bose Condensates with Rashba Spin-Orbit Coupling

NASA Astrophysics Data System (ADS)

Liao, Renyuan

2018-04-01

We developed a functional integral formulation for the stripe phase of spinor Bose-Einstein condensates with Rashba spin-orbit coupling. The excitation spectrum is found to exhibit double gapless band structures, identified to be two Goldstone modes resulting from spontaneously broken internal gauge symmetry and translational invariance symmetry. The sound velocities display anisotropic behavior with the lower branch vanishing in the direction perpendicular to the stripe in the x -y plane. At the transition point between the plane-wave phase and the stripe phase, physical quantities such as fluctuation correction to the ground-state energy and quantum depletion of the condensates exhibit discontinuity, characteristic of the first-order phase transition. Despite strong quantum fluctuations induced by Rashba spin-orbit coupling, we show that the supersolid phase is stable against quantum depletion. Finally, we extend our formulation to finite temperatures to account for interactions between excitations.

Phase Transitions in Definite Total Spin States of Two-Component Fermi Gases.

PubMed

Yurovsky, Vladimir A

2017-05-19

Second-order phase transitions have no latent heat and are characterized by a change in symmetry. In addition to the conventional symmetric and antisymmetric states under permutations of bosons and fermions, mathematical group-representation theory allows for non-Abelian permutation symmetry. Such symmetry can be hidden in states with defined total spins of spinor gases, which can be formed in optical cavities. The present work shows that the symmetry reveals itself in spin-independent or coordinate-independent properties of these gases, namely as non-Abelian entropy in thermodynamic properties. In weakly interacting Fermi gases, two phases appear associated with fermionic and non-Abelian symmetry under permutations of particle states, respectively. The second-order transitions between the phases are characterized by discontinuities in specific heat. Unlike other phase transitions, the present ones are not caused by interactions and can appear even in ideal gases. Similar effects in Bose gases and strong interactions are discussed.

Isotopic Shift of Atom-Dimer Efimov Resonances in K-Rb Mixtures: Critical Effect of Multichannel Feshbach Physics.

PubMed

Kato, K; Wang, Yujun; Kobayashi, J; Julienne, P S; Inouye, S

2017-04-21

Multichannel Efimov physics is investigated in ultracold heteronuclear admixtures of K and Rb atoms. We observe a shift in the scattering length where the first atom-dimer resonance appears in the ^{41}K-^{87}Rb system relative to the position of the previously observed atom-dimer resonance in the ^{40}K-^{87}Rb system. This shift is well explained by our calculations with a three-body model including van der Waals interactions, and, more importantly, multichannel spinor physics. With only minor differences in the atomic masses of the admixtures, the shift in the atom-dimer resonance positions can be cleanly ascribed to the isolated and overlapping Feshbach resonances in the ^{40}K-^{87}Rb and ^{41}K-^{87}Rb systems, respectively. Our study demonstrates the role of multichannel Feshbach physics in determining Efimov resonances in heteronuclear three-body systems.

ELECTRONIC STRUCTURE FOR THE GROUND STATE OF T1H FROM RELATIVISTIC MULTICONFIGURATION SCF CALCULATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christiansen, P.A.; Pitzer, K.S.

The dissociation curve for the ground state of TlH was computed using a relativistic {omega}-{omega} coupling formalism. The relativistic effects represented by the Dirac equation were introduced using effective potentials generated from atomic Dirac-Fock wave functions using a generalization of the improved effective potential formulation of Christiansen, Lee, and Pitzer. The multiconfiguration SCF treatment used is a generalization of the two-component molecular spinor formalism of Lee, Ermler, and Pitzer. Using a five configuration wave function we were able to obtain approximately 85% of the experimental dissociation energy. Our computations indicate that the bond is principally sigma in form, despite themore » large spin-orbit splitting in atomic thallium. Furthermore the bond appears to be slightly ionic (Tl{sup +}H{sup -}) with about 0.3 extra electron charge on the hydrogen.« less

Electronic structure for the ground state of TlH from relativistic multiconfiguration SCF calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christiansen, P.A.; Pitzer, K.S.

The dissociation curve for the ground state of TlH was computed using a relativistic ..omega..--..omega.. coupling formalism. The relativistic effects represented by the Dirac equation were introduced using effective potentials generated from atomic Dirac--Fock wave functions using a generalization of the improved effective potential formulation of Christiansen, Lee, and Pitzer. The multiconfiguration SCF treatment used is a generalization of the two-component molecular spinor formalism of Lee, Ermler, and Pitzer. Using a five configuration wave function we were able to obtain approximately 85% of the experimental dissociation energy. Our computations indicate that the bond is principally sigma in form, despite themore » large spin--orbit splitting in atomic thallium. Furthermore the bond appears to be slightly ionic (Tl/sup +/H/sup -/) with about 0.3 extra electron charge on the hydrogen.« less

Theoretical investigation of gas-surface interactions

NASA Technical Reports Server (NTRS)

Dyall, Kenneth G.

1990-01-01

A Dirac-Hartree-Fock code was developed for polyatomic molecules. The program uses integrals over symmetry-adapted real spherical harmonic Gaussian basis functions generated by a modification of the MOLECULE integrals program. A single Gaussian function is used for the nuclear charge distribution, to ensure proper boundary conditions at the nuclei. The Gaussian primitive functions are chosen to satisfy the kinetic balance condition. However, contracted functions which do not necessarily satisfy this condition may be used. The Fock matrix is constructed in the scalar basis and transformed to a jj-coupled 2-spinor basis before diagonalization. The program was tested against numerical results for atoms with a Gaussian nucleus and diatomic molecules with point nuclei. The energies converge on the numerical values as the basis set size is increased. Full use of molecular symmetry (restricted to D sub 2h and subgroups) is yet to be implemented.

{sup 85}Rb tunable-interaction Bose-Einstein condensate machine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Altin, P. A.; Robins, N. P.; Doering, D.

We describe our experimental setup for creating stable Bose-Einstein condensates (BECs) of {sup 85}Rb with tunable interparticle interactions. We use sympathetic cooling with {sup 87}Rb in two stages, initially in a tight Ioffe-Pritchard magnetic trap and subsequently in a weak, large-volume, crossed optical dipole trap, using the 155 G Feshbach resonance to manipulate the elastic and inelastic scattering properties of the {sup 85}Rb atoms. Typical {sup 85}Rb condensates contain 4x10{sup 4} atoms with a scattering length of a=+200a{sub 0}. Many aspects of the design presented here could be adapted to other dual-species BEC machines, including those involving degenerate Fermi-Bose mixtures.more » Our minimalist apparatus is well suited to experiments on dual-species and spinor Rb condensates, and has several simplifications over the {sup 85}Rb BEC machine at JILA, which we discuss at the end of this article.« less

A minimal approach to the scattering of physical massless bosons

NASA Astrophysics Data System (ADS)

Boels, Rutger H.; Luo, Hui

2018-05-01

Tree and loop level scattering amplitudes which involve physical massless bosons are derived directly from physical constraints such as locality, symmetry and unitarity, bypassing path integral constructions. Amplitudes can be projected onto a minimal basis of kinematic factors through linear algebra, by employing four dimensional spinor helicity methods or at its most general using projection techniques. The linear algebra analysis is closely related to amplitude relations, especially the Bern-Carrasco-Johansson relations for gluon amplitudes and the Kawai-Lewellen-Tye relations between gluons and graviton amplitudes. Projection techniques are known to reduce the computation of loop amplitudes with spinning particles to scalar integrals. Unitarity, locality and integration-by-parts identities can then be used to fix complete tree and loop amplitudes efficiently. The loop amplitudes follow algorithmically from the trees. A number of proof-of-concept examples are presented. These include the planar four point two-loop amplitude in pure Yang-Mills theory as well as a range of one loop amplitudes with internal and external scalars, gluons and gravitons. Several interesting features of the results are highlighted, such as the vanishing of certain basis coefficients for gluon and graviton amplitudes. Effective field theories are naturally and efficiently included into the framework. Dimensional regularisation is employed throughout; different regularisation schemes are worked out explicitly. The presented methods appear most powerful in non-supersymmetric theories in cases with relatively few legs, but with potentially many loops. For instance, in the introduced approach iterated unitarity cuts of four point amplitudes for non-supersymmetric gauge and gravity theories can be computed by matrix multiplication, generalising the so-called rung-rule of maximally supersymmetric theories. The philosophy of the approach to kinematics also leads to a technique to control colour quantum numbers of scattering amplitudes with matter, especially efficient in the adjoint and fundamental representations.

On a Microscopic Representation of Space-Time V

NASA Astrophysics Data System (ADS)

Dahm, R.

2017-01-01

In previous parts of this publication series, starting from the Dirac algebra and SU*(4), the ’dual’ compact rank-3 group SU(4) and Lie theory, we have developed some arguments and the reasoning to use (real) projective and (line) Complex geometry directly. Here, we want to extend this approach further in terms of line and Complex geometry and give some analytical examples. As such, we start from quadratic Complexe which we’ve identified in parts III and IV already as yielding naturally the ’light cone’ x_12 + x_22 + x_32 - x_02 = 0 when being related to (homogeneous) point coordinates x_α ^2 and infinitesimal dynamics by tetrahedral Complexe (or line elements). This introduces naturally projective transformations by preserving anharmonic ratios. We summarize some old work of Plücker relating quadratic Complexe to optics and discuss briefly their relation to spherical (and Schrödinger-type) equations as well as an obvious interpretation based on homogeneous coordinates and relations to conics and second order surfaces. Discussing (linear) symplectic symmetry and line coordinates, the main purpose and thread within this paper, however, is the identification and discussion of special relativity as direct invariance properties of line/Complex coordinates as well as their relation to ’quantum field theory’ by complexification of point coordinates or Complexe. This can be established by the Lie mapping1 which relates lines/Complexe to sphere geometry so that SU(2), SU(2)×U(1), SU(2)×SU(2) and the Dirac spinor description emerge without additional assumptions. We give a short outlook in that quadratic Complexe are related to dynamics e.g. power expressions in terms of six-vector products of Complexe, and action principles may be applied. (Quadratic) products like {Fμ ν }{Fμ ν }{{ or }}{Fα {{ }μ ν }}Fμ ν ^α ,1 ≤ α ≤ 3 are natural quadratic Complex expressions which may be extended by line constraints λk · ɛ = 0 with respect to an ’action principle’ so that we identify ’quantum field theory’ with projective or line/Complex geometry having applied the Lie mapping.

Navigating around the algebraic jungle of QCD: efficient evaluation of loop helicity amplitudes

NASA Astrophysics Data System (ADS)

Lam, C. S.

1993-05-01

A method is developed whereby spinor helicity techniques can be used to simlify the calculation of loop amplitudes. This is achieved by using the Feynman-parameter representation where the offending off-shell loop momenta do not appear. Other shortcuts motivated by the Bern-Kosower one-loop string calculations can be incorporated into the formalism. This includes color reorganization into Chan-Paton factors and the use of background Feynman gauge. This method is applicable to any Feynman diagram with any number of loops as long as the external masses can be ignored. In order to minimize the very considerable algebra encountered in non-abelian gauge theories, graphical methods are developed for most of the calculations. This enables the large number of terms encountered to be organized implicitly in the Feynman diagram without the necessity of writing down any of them algebraically. A one-loop four-gluon amplitude in a particular helicity configuration is computed explicitly to illustrate the method.

The Wave Logic of Consciousness: A Hypothesis

NASA Astrophysics Data System (ADS)

Orlov, Yuri F.

1982-01-01

A physical model is proposed for volitional decision making. It is postulated that consciousness reduces doubt states of the brain into labels by a quantum-mechanical measurement act of free choice. Elementary doubt states illustrate analogical encodement of information having “insufficient resolution” from a classical viewpoint. Measures of certitude (inner conviction) and doubt are formulated. “Adequate propositions” for nonclassical statements, e.g., Hamlet's soliloquy, are constructed. A role is proposed for the superposition principle in imagination and creativity. Experimental predictions are offered for positive and negative interference of doubts. Necessary criteria are made explicit for doubting sense information. Wholeness of perception is illustrated using irreducible, unitary representations of n-valued logics. The interpreted formalism includes nonclassical features of doubt, e.g., scalor representations for imprecise propositions and state changes due to self-reflection. The “liar paradox” is resolved. An internal origin is suggested for spinor dichotomies, e.g., “true-false” and “good-bad,” analogous to particle production.

Relativistic Prolapse-Free Gaussian Basis Sets of Quadruple-ζ Quality: (aug-)RPF-4Z. III. The f-Block Elements.

PubMed

Teodoro, Tiago Quevedo; Visscher, Lucas; da Silva, Albérico Borges Ferreira; Haiduke, Roberto Luiz Andrade

2017-03-14

The f-block elements are addressed in this third part of a series of prolapse-free basis sets of quadruple-ζ quality (RPF-4Z). Relativistic adapted Gaussian basis sets (RAGBSs) are used as primitive sets of functions while correlating/polarization (C/P) functions are chosen by analyzing energy lowerings upon basis set increments in Dirac-Coulomb multireference configuration interaction calculations with single and double excitations of the valence spinors. These function exponents are obtained by applying the RAGBS parameters in a polynomial expression. Moreover, through the choice of C/P characteristic exponents from functions of lower angular momentum spaces, a reduction in the computational demand is attained in relativistic calculations based on the kinetic balance condition. The present study thus complements the RPF-4Z sets for the whole periodic table (Z ≤ 118). The sets are available as Supporting Information and can also be found at http://basis-sets.iqsc.usp.br .

Universality and Quantum Criticality of the One-Dimensional Spinor Bose Gas

NASA Astrophysics Data System (ADS)

PâÅ£u, Ovidiu I.; Klümper, Andreas; Foerster, Angela

2018-06-01

We investigate the universal thermodynamics of the two-component one-dimensional Bose gas with contact interactions in the vicinity of the quantum critical point separating the vacuum and the ferromagnetic liquid regime. We find that the quantum critical region belongs to the universality class of the spin-degenerate impenetrable particle gas which, surprisingly, is very different from the single-component case and identify its boundaries with the peaks of the specific heat. In addition, we show that the compressibility Wilson ratio, which quantifies the relative strength of thermal and quantum fluctuations, serves as a good discriminator of the quantum regimes near the quantum critical point. Remarkably, in the Tonks-Girardeau regime, the universal contact develops a pronounced minimum, reflected in a counterintuitive narrowing of the momentum distribution as we increase the temperature. This momentum reconstruction, also present at low and intermediate momenta, signals the transition from the ferromagnetic to the spin-incoherent Luttinger liquid phase and can be detected in current experiments with ultracold atomic gases in optical lattices.

Hastatic order in URu2Si2 : Hybridization with a twist

NASA Astrophysics Data System (ADS)

Chandra, Premala; Coleman, Piers; Flint, Rebecca

2015-05-01

The broken symmetry that develops below 17.5 K in the heavy fermion compound URu2Si2 has long eluded identification. Here we argue that the recent observation of Ising quasiparticles in URu2Si2 results from a spinor hybridization order parameter that breaks double time-reversal symmetry by mixing states of integer and half-integer spin. Such "hastatic order" (hasta: [Latin] spear) hybridizes Kramers conduction electrons with Ising, non-Kramers 5 f2 states of the uranium atoms to produce Ising quasiparticles. The development of a spinorial hybridization at 17.5 K accounts for both the large entropy of condensation and the magnetic anomaly observed in torque magnetometry. This paper develops the theory of hastatic order in detail, providing the mathematical development of its key concepts. Hastatic order predicts a tiny transverse moment in the conduction sea, a colossal Ising anisotropy in the nonlinear susceptibility anomaly and a resonant energy-dependent nematicity in the tunneling density of states.

BOOK REVIEW: Path Integrals in Field Theory: An Introduction

NASA Astrophysics Data System (ADS)

Ryder, Lewis

2004-06-01

In the 1960s Feynman was known to particle physicists as one of the people who solved the major problems of quantum electrodynamics, his contribution famously introducing what are now called Feynman diagrams. To other physicists he gained a reputation as the author of the Feynman Lectures on Physics; in addition some people were aware of his work on the path integral formulation of quantum theory, and a very few knew about his work on gravitation and Yang--Mills theories, which made use of path integral methods. Forty years later the scene is rather different. Many of the problems of high energy physics are solved; and the standard model incorporates Feynman's path integral method as a way of proving the renormalisability of the gauge (Yang--Mills) theories involved. Gravitation is proving a much harder nut to crack, but here also questions of renormalisability are couched in path-integral language. What is more, theoretical studies of condensed matter physics now also appeal to this technique for quantisation, so the path integral method is becoming part of the standard apparatus of theoretical physics. Chapters on it appear in a number of recent books, and a few books have appeared devoted to this topic alone; the book under review is a very recent one. Path integral techniques have the advantage of enormous conceptual appeal and the great disadvantage of mathematical complexity, this being partly the result of messy integrals but more fundamentally due to the notions of functional differentiation and integration which are involved in the method. All in all this subject is not such an easy ride. Mosel's book, described as an introduction, is aimed at graduate students and research workers in particle physics. It assumes a background knowledge of quantum mechanics, both non-relativistic and relativistic. After three chapters on the path integral formulation of non-relativistic quantum mechanics there are eight chapters on scalar and spinor field theory, followed by three on gauge field theories---quantum electrodynamics and Yang--Mills theories, Faddeev--Popov ghosts and so on.There is no treatment of the quantisation of gravity.Thus in about 200 pages the reader has the chance to learn in some detail about a most important area of modern physics. The subject is tough but the style is clear and pedagogic, results for the most part being derived explicitly. The choice of topics included is main-stream and sensible and one has a clear sense that the author knows where he is going and is a reliable guide. Path Integrals in Field Theory is clearly the work of a man with considerable teaching experience and is recommended as a readable and helpful account of a rather non-trivial subject.

Single-Photon Emission of a Hydrogenlike Atom

NASA Astrophysics Data System (ADS)

Skobelev, V. V.

2016-11-01

Implementing a previously obtained, original solution of the Dirac equation for an electron in the field of a nucleus ( Ze) expressed in terms of the wave function of the corresponding Schrödinger equation and its derivatives in spherical coordinates and the spin projection operator Σ3 associated with the eigenfunction, taking into account in each component of the spinor the leading term of the expansion in the small parameter ( Zα), α = e 2 / ħc ≈ 1 / 137, the partial probabilities W of emission of a photon ( Zα)* → ( Zα) + γ have been calculated. Here two orthogonal states of the linear polarization of the photon, and also the spin states of the electron, which previously had not been taken into consideration, have been taken into account in the transverse gauge. It turns out that the probabilities W of emission of a photon per unit time for any allowed transitions are proportional to (Zα)4, as was previously accepted, and the selection rules for the quantum number m have the usual form Δ m = 0,±1. It was found that a spin flip does not take place during emission. In contrast to the customary situation with the selection rules for the quantum number l being of the form Δ l = ±1, for Δ m = ±1 there also exist integrals over dcosθ which are not equal to zero for undetermined odd values of Δ l. In this, and also in a fundamentally different dependence of the amplitude on the quantum numbers consist the differences from the traditional approach to the problem. Necessary conditions are formulated, under the fulfillment of which the selection rules for l are not changed, having values Δ l = ±1 for arbitrary Δ m, but it was not possible, however, to give a complete proof of these rules.

Quantum Electrodynamics in d=3 from the ε Expansion.

PubMed

Di Pietro, Lorenzo; Komargodski, Zohar; Shamir, Itamar; Stamou, Emmanuel

2016-04-01

We study quantum electrodynamics in d=3 coupled to N_{f} flavors of fermions. The theory flows to an IR fixed point for N_{f} larger than some critical number N_{f}^{c}. For N_{f}≤N_{f}^{c}, chiral-symmetry breaking is believed to take place. In analogy with the Wilson-Fisher description of the critical O(N) models in d=3, we make use of the existence of a fixed point in d=4-2ε to study the three-dimensional conformal theory. We compute, in perturbation theory, the IR dimensions of fermion bilinear and quadrilinear operators. For small N_{f}, a quadrilinear operator can become relevant in the IR and destabilize the fixed point. Therefore, the epsilon expansion can be used to estimate N_{f}^{c}. An interesting novelty compared to the O(N) models is that the theory in d=3 has an enhanced symmetry due to the structure of 3D spinors. We identify the operators in d=4-2ε that correspond to the additional conserved currents at d=3 and compute their infrared dimensions.

Quasi-Dirac neutrino oscillations

NASA Astrophysics Data System (ADS)

Anamiati, Gaetana; Fonseca, Renato M.; Hirsch, Martin

2018-05-01

Dirac neutrino masses require two distinct neutral Weyl spinors per generation, with a special arrangement of masses and interactions with charged leptons. Once this arrangement is perturbed, lepton number is no longer conserved and neutrinos become Majorana particles. If these lepton number violating perturbations are small compared to the Dirac mass terms, neutrinos are quasi-Dirac particles. Alternatively, this scenario can be characterized by the existence of pairs of neutrinos with almost degenerate masses, and a lepton mixing matrix which has 12 angles and 12 phases. In this work we discuss the phenomenology of quasi-Dirac neutrino oscillations and derive limits on the relevant parameter space from various experiments. In one parameter perturbations of the Dirac limit, very stringent bounds can be derived on the mass splittings between the almost degenerate pairs of neutrinos. However, we also demonstrate that with suitable changes to the lepton mixing matrix, limits on such mass splittings are much weaker, or even completely absent. Finally, we consider the possibility that the mass splittings are too small to be measured and discuss bounds on the new, nonstandard lepton mixing angles from current experiments for this case.

Measuring the quantum geometric tensor in two-dimensional photonic and exciton-polariton systems

NASA Astrophysics Data System (ADS)

Bleu, O.; Solnyshkov, D. D.; Malpuech, G.

2018-05-01

We propose theoretically a method that allows to measure all the components of the quantum geometric tensor (the metric tensor and the Berry curvature) in a photonic system. The method is based on standard optical measurements. It applies to two-band systems, which can be mapped to a pseudospin, and to four-band systems, which can be described by two entangled pseudospins. We apply this method to several specific cases. We consider a 2D planar cavity with two polarization eigenmodes, where the pseudospin measurement can be performed via polarization-resolved photoluminescence. We also consider the s band of a staggered honeycomb lattice with polarization-degenerate modes (scalar photons), where the sublattice pseudospin can be measured by performing spatially resolved interferometric measurements. We finally consider the s band of a honeycomb lattice with polarized (spinor) photons as an example of a four-band model. We simulate realistic experimental situations in all cases. We find the photon eigenstates by solving the Schrödinger equation including pumping and finite lifetime, and then simulate the measurements to finally extract realistic mappings of the k-dependent tensor components.

Derivation of Einstein-Cartan theory from general relativity

NASA Astrophysics Data System (ADS)

Petti, Richard

2015-04-01

General relativity cannot describe exchange of classical intrinsic angular momentum and orbital angular momentum. Einstein-Cartan theory fixes this problem in the least invasive way. In the late 20th century, the consensus view was that Einstein-Cartan theory requires inclusion of torsion without adequate justification, it has no empirical support (though it doesn't conflict with any known evidence), it solves no important problem, and it complicates gravitational theory with no compensating benefit. In 1986 the author published a derivation of Einstein-Cartan theory from general relativity, with no additional assumptions or parameters. Starting without torsion, Poincaré symmetry, classical or quantum spin, or spinors, it derives torsion and its relation to spin from a continuum limit of general relativistic solutions. The present work makes the case that this computation, combined with supporting arguments, constitutes a derivation of Einstein-Cartan theory from general relativity, not just a plausibility argument. This paper adds more and simpler explanations, more computational details, correction of a factor of 2, discussion of limitations of the derivation, and discussion of some areas of gravitational research where Einstein-Cartan theory is relevant.

Noncommutative Differential Geometry of Generalized Weyl Algebras

NASA Astrophysics Data System (ADS)

Brzeziński, Tomasz

2016-06-01

Elements of noncommutative differential geometry of Z-graded generalized Weyl algebras A(p;q) over the ring of polynomials in two variables and their zero-degree subalgebras B(p;q), which themselves are generalized Weyl algebras over the ring of polynomials in one variable, are discussed. In particular, three classes of skew derivations of A(p;q) are constructed, and three-dimensional first-order differential calculi induced by these derivations are described. The associated integrals are computed and it is shown that the dimension of the integral space coincides with the order of the defining polynomial p(z). It is proven that the restriction of these first-order differential calculi to the calculi on B(p;q) is isomorphic to the direct sum of degree 2 and degree -2 components of A(p;q). A Dirac operator for B(p;q) is constructed from a (strong) connection with respect to this differential calculus on the (free) spinor bimodule defined as the direct sum of degree 1 and degree -1 components of A(p;q). The real structure of KO-dimension two for this Dirac operator is also described.

Local metrics admitting a principal Killing-Yano tensor with torsion

NASA Astrophysics Data System (ADS)

Houri, Tsuyoshi; Kubizňák, David; Warnick, Claude M.; Yasui, Yukinori

2012-08-01

In this paper we initiate a classification of local metrics admitting the principal Killing-Yano tensor with a skew-symmetric torsion. It is demonstrated that in such spacetimes rank-2 Killing tensors occur naturally and mutually commute. We reduce the classification problem to that of solving a set of partial differential equations, and we present some solutions to these PDEs. In even dimensions, three types of local metrics are obtained: one of them naturally generalizes the torsion-less case while the others occur only when the torsion is present. In odd dimensions, we obtain more varieties of local metrics. The explicit metrics constructed in this paper are not the most general possible admitting the required symmetry; nevertheless, it is demonstrated that they cover a wide variety of solutions of various supergravities, such as the Kerr-Sen black holes of (un-)gauged Abelian heterotic supergravity, the Chong-Cvetic-Lü-Pope black hole solution of five-dimensional minimal supergravity or the Kähler with torsion manifolds. The relation between generalized Killing-Yano tensors and various torsion Killing spinors is also discussed.

Space-Time Crystal and Space-Time Group

NASA Astrophysics Data System (ADS)

Xu, Shenglong; Wu, Congjun

2018-03-01

Crystal structures and the Bloch theorem play a fundamental role in condensed matter physics. We extend the static crystal to the dynamic "space-time" crystal characterized by the general intertwined space-time periodicities in D +1 dimensions, which include both the static crystal and the Floquet crystal as special cases. A new group structure dubbed a "space-time" group is constructed to describe the discrete symmetries of a space-time crystal. Compared to space and magnetic groups, the space-time group is augmented by "time-screw" rotations and "time-glide" reflections involving fractional translations along the time direction. A complete classification of the 13 space-time groups in one-plus-one dimensions (1 +1 D ) is performed. The Kramers-type degeneracy can arise from the glide time-reversal symmetry without the half-integer spinor structure, which constrains the winding number patterns of spectral dispersions. In 2 +1 D , nonsymmorphic space-time symmetries enforce spectral degeneracies, leading to protected Floquet semimetal states. We provide a general framework for further studying topological properties of the (D +1 )-dimensional space-time crystal.

Space-Time Crystal and Space-Time Group.

PubMed

Xu, Shenglong; Wu, Congjun

2018-03-02

Crystal structures and the Bloch theorem play a fundamental role in condensed matter physics. We extend the static crystal to the dynamic "space-time" crystal characterized by the general intertwined space-time periodicities in D+1 dimensions, which include both the static crystal and the Floquet crystal as special cases. A new group structure dubbed a "space-time" group is constructed to describe the discrete symmetries of a space-time crystal. Compared to space and magnetic groups, the space-time group is augmented by "time-screw" rotations and "time-glide" reflections involving fractional translations along the time direction. A complete classification of the 13 space-time groups in one-plus-one dimensions (1+1D) is performed. The Kramers-type degeneracy can arise from the glide time-reversal symmetry without the half-integer spinor structure, which constrains the winding number patterns of spectral dispersions. In 2+1D, nonsymmorphic space-time symmetries enforce spectral degeneracies, leading to protected Floquet semimetal states. We provide a general framework for further studying topological properties of the (D+1)-dimensional space-time crystal.

Integrands for QCD rational terms and {N} = {4} SYM from massive CSW rules

NASA Astrophysics Data System (ADS)

Elvang, Henriette; Freedman, Daniel Z.; Kiermaier, Michael

2012-06-01

We use massive CSW rules to derive explicit compact expressions for integrands of rational terms in QCD with any number of external legs. Specifically, we present all- n integrands for the one-loop all-plus and one-minus gluon amplitudes in QCD. We extract the finite part of spurious external-bubble contributions systematically; this is crucial for the application of integrand-level CSW rules in theories without supersymmetry. Our approach yields integrands that are independent of the choice of CSW reference spinor even before integration. Furthermore, we present a recursive derivation of the recently proposed massive CSW-style vertex expansion for massive tree amplitudes and loop integrands on the Coulomb-branch of {N} = {4} SYM. The derivation requires a careful study of boundary terms in all-line shift recursion relations, and provides a rigorous (albeit indirect) proof of the recently proposed construction of massive amplitudes from soft-limits of massless on-shell amplitudes. We show that the massive vertex expansion manifestly preserves all holomorphic and half of the anti-holomorphic supercharges, diagram-by-diagram, even off-shell.

Using time reversal to detect entanglement and spreading of quantum information

NASA Astrophysics Data System (ADS)

Gaerttner, Martin

2017-04-01

Characterizing and understanding the states of interacting quantum systems and their non-equilibrium dynamics is the goal of quantum simulation. For this it is crucial to find experimentally feasible means for quantifying how entanglement and correlation build up and spread. The ability of analog quantum simulators to reverse the unitary dynamics of quantum many-body systems provides new tools in this quest. One such tool is the multiple-quantum coherence (MQC) spectrum previously used in NMR spectroscopy which can now be studied in so far inaccessible parameter regimes near zero temperature in highly controllable environments. I present recent progress in relating the MQC spectrum to established entanglement witnesses such as quantum Fisher information. Recognizing the MQC as out-of-time-order correlation functions, which quantify the spreading, or scrambling, of quantum information, allows us to establish a connection between these quantities and multi-partite entanglement. I will show recent experimental results obtained with a trapped ion quantum simulator and a spinor BEC illustrating the power of time reversal protocols. Supported by: JILA-NSF-PFC-1125844, NSF-PHY-1521080, ARO, AFOSR, AFOSR-MURI, DARPA, NIST.

Photoinduced dynamics to photoluminescence in Ln3+ (Ln = Ce, Pr) doped β-NaYF4 nanocrystals computed in basis of non-collinear spin DFT with spin-orbit coupling

NASA Astrophysics Data System (ADS)

Han, Yulun; Vogel, Dayton J.; Inerbaev, Talgat M.; May, P. Stanley; Berry, Mary T.; Kilin, Dmitri S.

2018-03-01

In this work, non-collinear spin DFT + U approaches with spin-orbit coupling (SOC) are applied to Ln3+ doped β-NaYF4 (Ln = Ce, Pr) nanocrystals in Vienna ab initio Simulation Package taking into account unpaired spin configurations using the Perdew-Burke-Ernzerhof functional in a plane wave basis set. The calculated absorption spectra from non-collinear spin DFT + U approaches are compared with that from spin-polarised DFT + U approaches. The spectral difference indicates the importance of spin-flip transitions of Ln3+ ions. Suite of codes for nonadiabatic dynamics has been developed for 2-component spinor orbitals. On-the-fly nonadiabatic coupling calculations provide transition probabilities facilitated by nuclear motion. Relaxation rates of electrons and holes are calculated using Redfield theory in the reduced density matrix formalism cast in the basis of non-collinear spin DFT + U with SOC. The emission spectra are calculated using the time-integrated method along the excited state trajectories based on nonadiabatic couplings.

Two-photon exchange force in scalar quantum electrodynamics: The asymptotic story

NASA Astrophysics Data System (ADS)

Sucher, J.

1994-04-01

The dependence of the potential V2γ arising from two-photon exchange between charged spinless systems on the one-photon exchange potential V1γ is examined. It is found that, unlike the case when at least one of the two systems is neutral, the form of V1γ can play a key role in determining the large-r behavior of V2γ. It is shown that if V1γ is defined in a way inspired by the use of the Coulomb gauge rather than the Feynman gauge, V2γ falls off as r-3, rather than as r-2. This result, which removes an apparent cognitive dissonance with the related work of Spruch, does not mean that the effective potential is inherently gauge dependent. Instead it highlights the fact that in this case the concept of the asymptotic behavior of V2γ is not as sharp as one might have thought. The relation of this result to an analogous one expected to hold for spinor QED and to the nonrelativistic form of the orbit-orbit interaction is also discussed.

Complete N-point superstring disk amplitude II. Amplitude and hypergeometric function structure

NASA Astrophysics Data System (ADS)

Mafra, Carlos R.; Schlotterer, Oliver; Stieberger, Stephan

2013-08-01

Using the pure spinor formalism in part I (Mafra et al., preprint [1]) we compute the complete tree-level amplitude of N massless open strings and find a striking simple and compact form in terms of minimal building blocks: the full N-point amplitude is expressed by a sum over (N-3)! Yang-Mills partial subamplitudes each multiplying a multiple Gaussian hypergeometric function. While the former capture the space-time kinematics of the amplitude the latter encode the string effects. This result disguises a lot of structure linking aspects of gauge amplitudes as color and kinematics with properties of generalized Euler integrals. In this part II the structure of the multiple hypergeometric functions is analyzed in detail: their relations to monodromy equations, their minimal basis structure, and methods to determine their poles and transcendentality properties are proposed. Finally, a Gröbner basis analysis provides independent sets of rational functions in the Euler integrals. In contrast to [1] here we use momenta redefined by a factor of i. As a consequence the signs of the kinematic invariants are flipped, e.g. |→|.

Single- or multi-flavor Kondo effect in graphene

NASA Astrophysics Data System (ADS)

Zhu, Zhen-Gang; Ding, Kai-He; Berakdar, Jamal

2010-06-01

Based on the tight-binding formalism, we investigate the Anderson and the Kondo model for an adatom magnetic impurity above graphene. Different impurity positions are analyzed. Employing a partial-wave representation we study the nature of the coupling between the impurity and the conducting electrons. The components from the two Dirac points are mixed while interacting with the impurity. Two configurations are considered explicitly: the adatom is above one atom (ADA), the other case is the adatom above the center the honeycomb (ADC). For ADA the impurity is coupled with one flavor for both A and B sublattice and both Dirac points. For ADC the impurity couples with multi-flavor states for a spinor state of the impurity. We show, explicitly for a 3d magnetic atom, dz2, (dxz,dyz), and (dx2- y2,dxy) couple respectively with the Γ1, Γ5(E1), and Γ6(E2) representations (reps) of C6v group in ADC case. The bases for these reps of graphene are also derived explicitly. For ADA we calculate the Kondo temperature.

Kinetic theory of fermions in curved spacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fidler, Christian; Pitrou, Cyril, E-mail: christian.fidler@uclouvain.be, E-mail: pitrou@iap.fr

We build a statistical description of fermions, taking into account the spin degree of freedom in addition to the momentum of particles, and we detail its use in the context of the kinetic theory of gases of fermions particles. We show that the one-particle distribution function needed to write a Liouville equation is a spinor valued operator. The degrees of freedom of this function are covariantly described by an intensity function and by a polarisation vector which are parallel transported by free streaming. Collisions are described on the microscopic level and lead to a Boltzmann equation for this operator. Wemore » apply our formalism to the case of weak interactions, which at low energies can be considered as a contact interaction between fermions, allowing us to discuss the structure of the collision term for a few typical weak-interaction mediated reactions. In particular we find for massive particles that a dipolar distribution of velocities in the interacting species is necessary to generate linear polarisation, as opposed to the case of photons for which linear polarisation is generated from the quadrupolar distribution of velocities.« less

Rethinking antiparticles. Hermann Weyl's contribution to neutrino physics

NASA Astrophysics Data System (ADS)

De Bianchi, Silvia

2018-02-01

This paper focuses on Hermann Weyl's two-component theory and frames it within the early development of different theories of spinors and the history of the discovery of parity violation in weak interactions. In order to show the implications of Weyl's theory, the paper discusses the case study of Ettore Majorana's symmetric theory of electron and positron (1937), as well as its role in inspiring Case's formulation of parity violation for massive neutrinos in 1957. In doing so, this paper clarifies the relevance of Weyl's and Majorana's theories for the foundations of neutrino physics and emphasizes which conceptual aspects of Weyl's approach led to Lee's and Yang's works on neutrino physics and to the solution of the theta-tau puzzle in 1957. This contribution thus sheds a light on the alleged "re-discovery" of Weyl's and Majorana's theories in 1957, by showing that this did not happen all of a sudden. On the contrary, the scientific community was well versed in applying these theories in the 1950s on the ground of previous studies that involved important actors in both Europe and United States.

Electromagnetic multipole moments of elementary spin-1/2, 1, and 3/2 particles

NASA Astrophysics Data System (ADS)

Delgado-Acosta, E. G.; Kirchbach, M.; Napsuciale, M.; Rodríguez, S.

2012-06-01

We study multipole decompositions of the electromagnetic currents of spin-1/2, 1, and 3/2 particles described in terms of representation-specific wave equations which are second order in the momenta and which emerge within the recently elaborated Poincaré covariant-projector method, where the respective Lagrangians explicitly depend on the Lorentz group generators of the representations of interest. The currents are then the ordinary linear Noether currents related to phase invariance, and present themselves always as two-terms motion-plus spin-magnetization currents. The spin-magnetization currents appear weighted by the gyromagnetic ratio g, a free parameter in the method which we fix either by unitarity of forward Compton scattering amplitudes in the ultraviolet for spin-1 and spin-3/2, or in the spin-1/2 case, by their asymptotic vanishing, thus ending up in all three cases with the universal g value of g=2. Within the method under discussion, we calculate the electric multipoles of the above spins for the spinor, the four-vector, and the four-vector-spinor representations, and find it favorable in some aspects, specifically in comparison with the conventional Proca and Rarita-Schwinger frameworks. We furthermore attend to the most general non-Lagrangian spin-3/2 currents, which are allowed by Lorentz invariance to be up to third order in the momenta and construct the linear-current equivalent of identical multipole moments of one of them. We conclude that nonlinear non-Lagrangian spin-3/2 currents are not necessarily more general and more advantageous than the linear spin-3/2 Lagrangian current emerging within the covariant-projector formalism. Finally, we test the representation dependence of the multipoles by placing spin-1 and spin-3/2 in the respective (1,0)⊕(0,1) and (3/2,0)⊕(0,3/2) single-spin representations. We observe representation independence of the charge monopoles and the magnetic dipoles, in contrast to the higher multipoles, which turn out to be representation-dependent. In particular, we find the bi-vector (1,0)⊕(0,1) to be characterized by an electric quadrupole moment of opposite sign to the one found in (1/2,1/2), and consequently to the W boson. This observation allows us to explain the positive electric quadrupole moment of the ρ meson extracted from recent analyses of the ρ meson electric form factor. Our finding points toward the possibility that the ρ-meson could transform as part of an antisymmetric tensor with an a1 mesonlike state as its representation companion, a possibility consistent with the empirically established ρ and a1 vector meson dominance of the hadronic vector and axial-vector currents.

Spin-orbit coupling in GaN/AlGaN wurtzite quantum wells

NASA Astrophysics Data System (ADS)

Penteado, Poliana H.; Fu, J. Y.; Bernardes, Esmerindo; Egues, J. Carlos

2012-02-01

We investigate the spin-orbit coupling for electrons in wurtzite quantum wells with two subbands [1]. By folding down the 8x8 Kane model, accounting for the s-pz orbital mixing [2, 3] absent in zincblende structures, we derive an effective 2x2 Hamiltonian for the conduction electrons. In this derivation we consider the renormalization of the spinor component of the conduction band wave function, which is crucial to properly obtain the corresponding spin-orbit couplings. In addition to the Rashba-type term arising from the bulk inversion asymmetry of the wurtzite lattice, we obtain the usual linear in momentum Rashba term induced by the structural inversion asymmetry of the well and; interestingly, we also find a new Rashba-like contribution. The spin-orbit coupling parameters are obtained via a self-consistent calculation. For completeness, the Dresselhaus term is also included in our calculation. [4pt] [1] Rafael S. Calsaverini, Esmerindo Bernardes, J. Carlos Egues, and Daniel Loss, Phys. Rev. B 78, 155313 (2008). [0pt] [2] L. C. Lew Yan Voon, M. Willatzen, and M. Cardona, Phys. Rev. B 53, 10703 (1996). [0pt] [3] J. Y. Fu and M. W. Wu, J. Appl. Phys 104, 093712 (2008).

BCS: the Scientific "Love of my Life"

NASA Astrophysics Data System (ADS)

Anderson, Philip W.

After short comments on my early addenda to BCS — gauge invariance and the Anderson-Higgs mechanism, the dirty superconductor "theorem," and the spinor representation — I focus on the interaction mechanisms which cause electron-electron pairing. These bifurcate into two almost non-overlapping classes. In order to cause electrons to pair in spite of the strong, repulsive, instantaneous Coulomb vertex, the electrons can evade each others' propinquity on the same site at the same time either dynamically, by retaining D° (s-wave) relative symmetry, but avoiding each other in time — called "dynamic screening" — or by assuming a non-symmetric relative wave function, avoiding each other in space. All simple metals and alloys, including all the (so far) technically useful superconductors, follow the former scheme. But starting with the first discovery of "heavy-electron" super-conductors in 1979, and continuing with the "organics" and the magnetic transition metal compounds such as the cuprates and the iron pnictides, it appears that the second class may turn out to be numerically superior and theoretically more fascinating. The basic interaction in many of these cases appears to be the "kinetic exchange" or superexchange characteristic of magnetic insulators.

Relativistic interpretation of the nature of the nuclear tensor force

NASA Astrophysics Data System (ADS)

Zong, Yao-Yao; Sun, Bao-Yuan

2018-02-01

The spin-dependent nature of the nuclear tensor force is studied in detail within the relativistic Hartree-Fock approach. The relativistic formalism for the tensor force is supplemented with an additional Lorentz-invariant tensor formalism in the σ-scalar channel, so as to take into account almost fully the nature of the tensor force brought about by the Fock diagrams in realistic nuclei. Specifically, the tensor sum rules are tested for the spin and pseudo-spin partners with and without nodes, to further understand the nature of the tensor force within the relativistic model. It is shown that the interference between the two components of nucleon spinors causes distinct violations of the tensor sum rules in realistic nuclei, mainly due to the opposite signs on the κ quantities of the upper and lower components, as well as the nodal difference. However, the sum rules can be precisely reproduced if the same radial wave functions are taken for the spin/pseudo-spin partners in addition to neglecting the lower/upper components, revealing clearly the nature of the tensor force. Supported by National Natural Science Foundation of China (11375076, 11675065) and the Fundamental Research Funds for the Central Universities (lzujbky-2016-30)

Anisotropic semivortices in dipolar spinor condensates controlled by Zeeman splitting

NASA Astrophysics Data System (ADS)

Liao, Bingjin; Li, Shoubo; Huang, Chunqing; Luo, Zhihuan; Pang, Wei; Tan, Haishu; Malomed, Boris A.; Li, Yongyao

2017-10-01

Spatially anisotropic solitary vortices, i.e., bright anisotropic vortex solitons (AVSs), supported by anisotropic dipole-dipole interactions, were recently predicted in spin-orbit-coupled binary Bose-Einstein condensates (BECs), in the form of two-dimensional semivortices (complexes built of zero-vorticity and vortical components). We demonstrate that the shape of the AVSs—horizontal or vertical, with respect to the in-plane polarization of the atomic dipole moments in the underlying BEC—may be effectively controlled by the strength Ω of the Zeeman splitting (ZS). A transition from the horizontal to vertical shape with the increase of Ω is found numerically and explained analytically. At the transition point, the AVS assumes the shape of an elliptical ring. The mobility of horizontal AVSs is studied, too, with the conclusion that, with the increase of Ω , their negative effective mass changes the sign to positive via a point at which the effective mass diverges. Lastly, we report a new species of inverted AVSs, with the zero-vorticity and vortex component placed in lower- and higher-energy components, as defined by the ZS. They are excited states, with respect to the ground states provided by the usual AVSs. Quite surprisingly, inverted AVSs are stable in a large parameter region.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herraiz, Joaquin Lopez

Experimental coincidence cross section and transverse-longitudinal asymmetry ATL have been obtained for the quasielastic (e,e'p) reaction in 16O, 12C, and {sup 208}Pb in constant q-ω kinematics in the missing momentum range -350 < p miss < 350 MeV/c. In these experiments, performed in experimental Hall A of the Thomas Jefferson National Accelerator Facility (JLAB), the beam energy and the momentum and angle of the scattered electrons were kept fixed, while the angle between the proton momentum and the momentum transfer q was varied in order to map out the missing momentum distribution. The experimental cross section and A TL asymmetrymore » have been compared with Monte Carlo simulations based on Distorted Wave Impulse Approximation (DWIA) calculations with both relativistic and non-relativistic spinor structure. The spectroscopic factors obtained for both models are in agreement with previous experimental values, while A TL measurements favor the relativistic DWIA calculation. This thesis describes the details of the experimental setup, the calibration of the spectrometers, the techniques used in the data analysis to derive the final cross sections and the A TL, the ingredients of the theoretical calculations employed and the comparison of the results with the simulations based on these theoretical models.« less

Schrödinger and Dirac solutions to few-body problems

NASA Astrophysics Data System (ADS)

Muolo, Andrea; Reiher, Markus

We elaborate on the variational solution of the Schrödinger and Dirac equations for small atomic and molecular systems without relying on the Born-Oppenheimer approximation. The all-particle equations of motion are solved in a numerical procedure that relies on the variational principle, Cartesian coordinates and parametrized explicitly correlated Gaussians functions. A stochastic optimization of the variational parameters allows the calculation of accurate wave functions for ground and excited states. Expectation values such as the radial and angular distribution functions or the dipole moment can be calculated. We developed a simple strategy for the elimination of the global translation that allows to generally adopt laboratory-fixed cartesian coordinates. Simple expressions for the coordinates and operators are then preserved throughout the formalism. For relativistic calculations we devised a kinetic-balance condition for explicitly correlated basis functions. We demonstrate that the kinetic-balance condition can be obtained from the row reduction process commonly applied to solve systems of linear equations. The resulting form of kinetic balance establishes a relation between all components of the spinor of an N-fermion system. ETH Zürich, Laboratorium für Physikalische Chemie, CH-8093 Zürich, Switzerland.

Classification of quench-dynamical behaviors in spinor condensates

NASA Astrophysics Data System (ADS)

Daǧ, Ceren B.; Wang, Sheng-Tao; Duan, L.-M.

2018-02-01

Thermalization of isolated quantum systems is a long-standing fundamental problem where different mechanisms are proposed over time. We contribute to this discussion by classifying the diverse quench-dynamical behaviors of spin-1 Bose-Einstein condensates, which includes well-defined quantum collapse and revivals, thermalization, and certain special cases. These special cases are either nonthermal equilibration with no revival but a collapse even though the system has finite degrees of freedom or no equilibration with no collapse and revival. Given that some integrable systems are already shown to demonstrate the weak form of eigenstate thermalization hypothesis (ETH), we determine the regions where ETH holds and fails in this integrable isolated quantum system. The reason behind both thermalizing and nonthermalizing behaviors in the same model under different initial conditions is linked to the discussion of "rare" nonthermal states existing in the spectrum. We also propose a method to predict the collapse and revival time scales and find how they scale with the number of particles in the condensate. We use a sudden quench to drive the system to nonequilibrium and hence the theoretical predictions given in this paper can be probed in experiments.

Polarization Transfer in the Reaction 4He($$\\vec{v}$$,e'$$\\vec{p}$$) 3H in the Quasielastic Scattering Region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dieterich, Sonja

2002-05-01

There has been a longstanding issue concerning possible nucleon modifications in a (dense) nuclear medium. Polarization transfer data for exclusive quasielastic electron scattering are a sensitive to the ratio of the electric and magnetic nucleon form factors in the medium. Although proper interpretation of the results requires accounting for such effects as final state interactions and meson exchange currents, their effect on polarization transfer is predicted to be small. Studies of model dependencies, e.g., the off-shell current operator and spinor distortions, have been done. Final results of a measurement of polarization transfer in the 4He(more » $$\\vec{v}$$,e'$$\\vec{p}$$) 3H reaction will be discussed. The experiments were carried out at MAMI, Mainz at a Q 2 of 0.4 GeV 2 and at the Thomas Jefferson Lab, Newport News, Virginia at the Q 2 values 0.5, 1.0, 1.6 and 2.6 GeV 2. Measured values of the transferred and induced polarization are compared with various theoretical calculations. The experiment showed a difference between the fully relativistic model with may indicate medium modifications of the form factor.« less

Hybridization with a twist: Hidden (hastatic) order in URu2Si2

NASA Astrophysics Data System (ADS)

Flint, Rebecca

The hidden order developing below 17.5K in the heavy fermion material URu2Si2 has eluded identification for over thirty years. A number of recent experiments have shed new light on the nature of this phase. In particular, de Haas-van Alphen measurements indicate nearly perfectly Ising quasiparticles deep in the hidden order phase, and recent nonlinear susceptibility measurements show that this strong Ising anisotropy persists up to and above the hidden order transition itself. Along with other features, this Ising anisotropy implies that the conduction electrons hybridize with a local Ising moment - a 5f2 state of the uranium atom with integer spin. As the hybridization mixes states of integer and half-integer spin, it is itself a spinor and this ``hastatic'' (hasta: [Latin] spear) order parameter therefore breaks both time-reversal and double time-reversal symmetries. A microscopic theory of hastatic order naturally unites a number of disparate experimental results from the large entropy of condensation to the spin rotational symmetry breaking seen in torque magnetometry, and provides a number of experimental predictions. Moreover, this new spinorial order parameter provides a window into a number of new heavy fermion phases.

Rigorous Relativistic Methods for Addressing {P}- and {T}-NONCONSERVATION in Heavy-Element Molecules

NASA Astrophysics Data System (ADS)

Fleig, Timo

2013-06-01

A new and rigorous method for accurate ab-initio calculations of the electron electric dipole moment {P,T}-odd interaction constant is presented. The approach uses string-based Configuration Interaction wavefunctions and Dirac four-component spinors as one-particle basis functions, and the {P,T}-odd constant is obtained as an expectation value over these correlated wavefunctions. The method has been applied to the HfF^+ molecular ion to determine spectroscopic constants for four low-lying electronic states. For one of these states (Ω = 1) we have determined a new accurate benchmark value for the effective electric field E_{ eff} correlating 34 valence and outer atomic core electrons and using wavefunction expansions with nearly 5 \\cdot 10^8 coefficients. For the Ω = 1 state of the ThO molecule the first ab-initio result for the electron EDM interaction constant is presented. Aspects of modern all-electron relativistic many-body approaches applicable to both atoms and molecules will be discussed, including perspectives for the treatment of other interesting candidate systems and {P}- or {P,T}-non-conserving effects in molecular systems. %Zero-kinetic-energy (ZEKE) photoelectron spectroscopy was used to probe the vibrational levels in the ground electronic state of the chlorobenzene cation using a two-color photoionization scheme via the S{_1} electronic state of the neutral. Exciting through different S{_1} vibrational levels has revealed mixing of some S{_1} normal coordinates in the ground state of the cation. A previously-identified Fermi resonance in the S{_1} state of the neutral is also confirmed by the ZEKE spectra. The adiabatic ionization energy is measured as 73 170±5 cm^{-1}. S. Knecht, H. J. Å. Jensen and T. Fleig J. Chem. Phys. {132}, 014108 (2010 T. Fleig, H. J. Å. Jensen, J. Olsen and L. Visscher J. Chem. Phys. {124}, 104106 (2006) T. Fleig and M. K. Nayak Phys. Rev. X {XXX}, XXXX (submitted). T. G. Wright, S. I. Panov and T. A. Miller J. Chem. Phys. {102}(12), XXXX March 1995.

Quantum supersymmetric Bianchi IX cosmology

NASA Astrophysics Data System (ADS)

Damour, Thibault; Spindel, Philippe

2014-11-01

We study the quantum dynamics of a supersymmetric squashed three-sphere by dimensionally reducing (to one timelike dimension) the action of D =4 simple supergravity for a S U (2 ) -homogeneous (Bianchi IX) cosmological model. The quantization of the homogeneous gravitino field leads to a 64-dimensional fermionic Hilbert space. After imposition of the diffeomorphism constraints, the wave function of the Universe becomes a 64-component spinor of spin(8,4) depending on the three squashing parameters, which satisfies Dirac-like, and Klein-Gordon-like, wave equations describing the propagation of a "quantum spinning particle" reflecting off spin-dependent potential walls. The algebra of the supersymmetry constraints and of the Hamiltonian one is found to close. One finds that the quantum Hamiltonian is built from operators that generate a 64-dimensional representation of the (infinite-dimensional) maximally compact subalgebra of the rank-3 hyperbolic Kac-Moody algebra A E3 . The (quartic-in-fermions) squared-mass term μ^ 2 entering the Klein-Gordon-like equation has several remarkable properties: (i) it commutes with all the other (Kac-Moody-related) building blocks of the Hamiltonian; (ii) it is a quadratic function of the fermion number NF; and (iii) it is negative in most of the Hilbert space. The latter property leads to a possible quantum avoidance of the singularity ("cosmological bounce"), and suggests imposing the boundary condition that the wave function of the Universe vanish when the volume of space tends to zero (a type of boundary condition which looks like a final-state condition when considering the big crunch inside a black hole). The space of solutions is a mixture of "discrete-spectrum states" (parametrized by a few constant parameters, and known in explicit form) and of continuous-spectrum states (parametrized by arbitrary functions entering some initial-value problem). The predominantly negative values of the squared-mass term lead to a "bottle effect" between small-volume universes and large-volume ones, and to a possible reduction of the continuous spectrum to a discrete spectrum of quantum states looking like excited versions of the Planckian-size universes described by the discrete states at fermionic levels NF=0 and 1.

Hidden role of Maxwell superalgebras in the free differential algebras of D = 4 and D = 11 supergravity

NASA Astrophysics Data System (ADS)

Ravera, Lucrezia

2018-03-01

The purpose of this paper is to show that the so-called Maxwell superalgebra in four dimensions, which naturally involves the presence of a nilpotent fermionic generator, can be interpreted as a hidden superalgebra underlying N=1, {D}=4 supergravity extended to include a 2-form gauge potential associated to a 2-index antisymmetric tensor. In this scenario, the theory is appropriately discussed in the context of Free Differential Algebras (an extension of the Maurer-Cartan equations to involve higher-degree differential forms). The study is then extended to the Free Differential Algebra describing D = 11 supergravity, showing that, also in this case, there exists a super-Maxwell algebra underlying the theory. The same extra spinors dual to the nilpotent fermionic generators whose presence is crucial for writing a supersymmetric extension of the Maxwell algebras, both in the D = 4 and in the D = 11 case, turn out to be fundamental ingredients also to reproduce the D = 4 and D = 11 Free Differential Algebras on ordinary superspace, whose basis is given by the supervielbein. The analysis of the gauge structure of the supersymmetric Free Differential Algebras is carried on taking into account the gauge transformations from the hidden supergroup-manifold associated with the Maxwell superalgebras.

Links between quantum physics and thought.

PubMed

Robson, Barry

2009-01-01

Quantum mechanics (QM) provides a variety of ideas that can assist in developing Artificial Intelligence for healthcare, and opens the possibility of developing a unified system of Best Practice for inference that will embrace both QM and classical inference. Of particular interest is inference in the hyperbolic-complex plane, the counterpart of the normal i-complex plane of basic QM. There are two reasons. First, QM appears to rotate from i-complex Hilbert space to hyperbolic-complex descriptions when observations are made on wave functions as particles, yielding classical results, and classical laws of probability manipulation (e.g. the law of composition of probabilities) then hold, whereas in the i-complex plane they do not. Second, i-complex Hilbert space is not the whole story in physics. Hyperbolic complex planes arise in extension from the Dirac-Clifford calculus to particle physics, in relativistic correction thereby, and in regard to spinors and twisters. Generalization of these forms resemble grammatical constructions and promote the idea that probability-weighted algebraic elements can be used to hold dimensions of syntactic and semantic meaning. It is also starting to look as though when a solution is reached by an inference system in the hyperbolic-complex, the hyperbolic-imaginary values disappear, while conversely hyperbolic-imaginary values are associated with the un-queried state of a system and goal seeking behavior.

Analytical energy gradient for the two-component normalized elimination of the small component method

NASA Astrophysics Data System (ADS)

Zou, Wenli; Filatov, Michael; Cremer, Dieter

2015-06-01

The analytical gradient for the two-component Normalized Elimination of the Small Component (2c-NESC) method is presented. The 2c-NESC is a Dirac-exact method that employs the exact two-component one-electron Hamiltonian and thus leads to exact Dirac spin-orbit (SO) splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000)]. The effect of spin-orbit coupling (SOC) on molecular geometries is analyzed utilizing the properties of the frontier orbitals and calculated SO couplings. It is shown that bond lengths can either be lengthened or shortened under the impact of SOC where in the first case the influence of low lying excited states with occupied antibonding orbitals plays a role and in the second case the jj-coupling between occupied antibonding and unoccupied bonding orbitals dominates. In general, the effect of SOC on bond lengths is relatively small (≤5% of the scalar relativistic changes in the bond length). However, large effects are found for van der Waals complexes Hg2 and Cn2, which are due to the admixture of more bonding character to the highest occupied spinors.

Lamb shift and fine structure at n =2 in a hydrogenlike muonic atom with the nuclear spin I =0

NASA Astrophysics Data System (ADS)

Korzinin, Evgeny Yu.; Shelyuto, Valery A.; Ivanov, Vladimir G.; Karshenboim, Savely G.

2018-01-01

The paper is devoted to the Lamb shift and fine structure in a hydrogenlike muonic atom with a spinless nucleus up to the order α5m with all the recoil corrections included. Enhanced contributions of a higher order are also considered. We present the results on the pure QED contribution and on the finite-nuclear-size contribution, proportional to RN2, with the higher-order corrections included. We also consider the consistency of the pure QED theory and the evaluation of the nuclear-structure effects. Most of the QED theory is the same as the theory for the case of the nuclear spin 1/2. Additional nuclear-spin-dependent terms are considered in detail. The issue of the difference for the theories with a spinor nucleus and a scalar one is discussed for the recoil contributions in the order (Zα ) 4m ,α (Zα ) 4m , and (Zα ) 5m . The numerical results are presented for the muonic atoms with two lightest scalar nuclei, helium-4 and beryllium-10. We compare the theory of those muonic atoms with theory for the muonic hydrogen. Some higher-order finite-nuclear-size corrections for the Lamb shift in muonic hydrogen are revisited.

Division Algebras, Supersymmetry and Higher Gauge Theory

NASA Astrophysics Data System (ADS)

Huerta, John Gmerek

2011-12-01

Starting from the four normed division algebras---the real numbers, complex numbers, quaternions and octonions, with dimensions k = 1, 2, 4 and 8, respectively---a systematic procedure gives a 3-cocycle on the Poincare Lie superalgebra in dimensions k + 2 = 3, 4, 6 and 10. A related procedure gives a 4-cocycle on the Poincare Lie superalgebra in dimensions k+3 = 4, 5, 7 and 11. The existence of these cocycles follow from certain spinor identities that hold only in these dimensions, and which are closely related to the existence of superstring and super-Yang--Mills theory in dimensions k + 2, and super-2-brane theory in dimensions k + 3. In general, an (n+1)-cocycle on a Lie superalgebra yields a 'Lie n-superalgebra': that is, roughly speaking, an n-term chain complex equipped with a bracket satisfying the axioms of a Lie superalgebra up to chain homotopy. We thus obtain Lie 2-superalgebras extending the Poincare superalgebra in dimensions 3, 4, 6, and 10, and Lie 3-superalgebras extending the Poincare superalgebra in dimensions 4, 5, 7 and 11. As shown in Sati, Schreiber and Stasheff's work on generalized connections valued in Lie n-superalgebras, Lie 2-superalgebra connections describe the parallel transport of strings, while Lie 3-superalgebra connections describe the parallel transport of 2-branes. Moreover, in the octonionic case, these connections concisely summarize the fields appearing in 10- and 11-dimensional supergravity. Generically, integrating a Lie n-superalgebra to a Lie n-supergroup yields a 'Lie n-supergroup' that is hugely infinite-dimensional. However, when the Lie n-superalgebra is obtained from an (n + 1)-cocycle on a nilpotent Lie superalgebra, there is a geometric procedure to integrate the cocycle to one on the corresponding nilpotent Lie supergroup. In general, a smooth (n+1)-cocycle on a supergroup yields a 'Lie n-supergroup': that is, a weak n-group internal to supermanifolds. Using our geometric procedure to integrate the 3-cocycle in dimensions 3, 4, 6 and 10, we obtain a Lie 2-supergroup extending the Poincare supergroup in those dimensions, and similarly integrating the 4-cocycle in dimensions 4, 5, 7 and 11, we obtain a Lie 3-supergroup extending the Poincare supergroup in those dimensions.

Wilsonian dark matter in string derived Z' model

NASA Astrophysics Data System (ADS)

Delle Rose, L.; Faraggi, A. E.; Marzo, C.; Rizos, J.

2017-09-01

The dark matter issue is among the most perplexing in contemporary physics. The problem is more enigmatic due to the wide range of possible solutions, ranging from the ultralight to the supermassive. String theory gives rise to plausible dark matter candidates due to the breaking of the non-Abelian grand unified theory (GUT) symmetries by Wilson lines. The physical spectrum then contains states that do not satisfy the quantization conditions of the unbroken GUT symmetry. Given that the Standard Model states are identified with broken GUT representations, and provided that any ensuing symmetry breakings are induced by components of GUT states, a remnant discrete symmetry remains that forbids the decay of the Wilsonian states. A class of such states are obtained in a heterotic-string-derived Z' model. The model exploits the spinor-vector duality symmetry, observed in the fermionic Z2×Z2 heterotic-string orbifolds, to generate a Z'∈E6 symmetry that may remain unbroken down to low energies. The E6 symmetry is broken at the string level with discrete Wilson lines. The Wilsonian dark matter candidates in the string-derived model are S O (10 ), and hence Standard Model, singlets and possess non-E6 U(1)Z' charges. Depending on the U(1)Z' breaking scale and the reheating temperature they give rise to different scenarios for the relic abundance, and are in accordance with the cosmological constraints.

Georges Lemaître: The Priest Who Invented the Big Bang

NASA Astrophysics Data System (ADS)

Lambert, Dominique

This contribution gives a concise survey of Georges Lemaître works and life, shedding some light on less-known aspects. Lemaître is a Belgian catholic priest who gave for the first time in 1927 the explanation of the Hubble law and who proposed in 1931 the "Primeval Atom Hypothesis", considered as the first step towards the Big Bang cosmology. But the scientific work of Lemaître goes far beyond Physical Cosmology. Indeed, he contributed also to the theory of Cosmis Rays, to the Spinor theory, to Analytical mechanics (regularization of 3- Bodies problem), to Numerical Analysis (Fast Fourier Transform), to Computer Science (he introduced and programmed the first computer of Louvain),… Lemaître took part to the "Science and Faith" debate. He defended a position that has some analogy with the NOMA principle, making a sharp distinction between what he called the "two paths to Truth" (a scientific one and a theological one). In particular, he never made a confusion between the theological concept of "creation" and the scientific notion of "natural beginning" (initial singularity). Lemaître was deeply rooted in his faith and sacerdotal vocation. Remaining a secular priest, he belonged to a community of priests called "The Friends of Jesus", characterized by a deep spirituality and special vows (for example the vow of poverty). He had also an apostolic activity amongst Chinese students.

On the Uniqueness and Consistency of Scattering Amplitudes

NASA Astrophysics Data System (ADS)

Rodina, Laurentiu

In this dissertation, we study constraints imposed by locality, unitarity, gauge invariance, the Adler zero, and constructability (scaling under BCFW shifts). In the first part we study scattering amplitudes as the unique mathematical objects which can satisfy various combinations of such principles. In all cases we find that locality and unitarity may be derived from gauge invariance (for Yang-Mills and General Relativity) or from the Adler zero (for the non-linear sigma model and the Dirac-Born-Infeld model), together with mild assumptions on the singularity structure and mass dimension. We also conjecture that constructability and locality together imply gauge invariance, hence also unitarity. All claims are proved through a soft expansion, and in the process we end re-deriving the well-known leading soft theorems for all four theories. Unlike other proofs of these theorems, we do not assume any form of factorization (unitarity). In the second part we show how tensions arising between gauge invariance (as encoded by spinor helicity variables in four dimensions), locality, unitarity and constructability give rise to various physical properties. These include high-spin no-go theorems, the equivalence principle, and the emergence of supersymmetry from spin 3/2 particles. We also complete the fully on-shell constructability proof of gravity amplitudes, by showing that the improved "bonus'' behavior of gravity under BCFW shifts is a simple consequence of Bose symmetry.

Analytical energy gradient for the two-component normalized elimination of the small component method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zou, Wenli; Filatov, Michael; Cremer, Dieter, E-mail: dcremer@smu.edu

2015-06-07

The analytical gradient for the two-component Normalized Elimination of the Small Component (2c-NESC) method is presented. The 2c-NESC is a Dirac-exact method that employs the exact two-component one-electron Hamiltonian and thus leads to exact Dirac spin-orbit (SO) splittings for one-electron atoms. For many-electron atoms and molecules, the effect of the two-electron SO interaction is modeled by a screened nucleus potential using effective nuclear charges as proposed by Boettger [Phys. Rev. B 62, 7809 (2000)]. The effect of spin-orbit coupling (SOC) on molecular geometries is analyzed utilizing the properties of the frontier orbitals and calculated SO couplings. It is shown thatmore » bond lengths can either be lengthened or shortened under the impact of SOC where in the first case the influence of low lying excited states with occupied antibonding orbitals plays a role and in the second case the jj-coupling between occupied antibonding and unoccupied bonding orbitals dominates. In general, the effect of SOC on bond lengths is relatively small (≤5% of the scalar relativistic changes in the bond length). However, large effects are found for van der Waals complexes Hg{sub 2} and Cn{sub 2}, which are due to the admixture of more bonding character to the highest occupied spinors.« less

Inverse scattering transform and soliton solutions for square matrix nonlinear Schrödinger equations with non-zero boundary conditions

NASA Astrophysics Data System (ADS)

Prinari, Barbara; Demontis, Francesco; Li, Sitai; Horikis, Theodoros P.

2018-04-01

The inverse scattering transform (IST) with non-zero boundary conditions at infinity is developed for an m × m matrix nonlinear Schrödinger-type equation which, in the case m = 2, has been proposed as a model to describe hyperfine spin F = 1 spinor Bose-Einstein condensates with either repulsive interatomic interactions and anti-ferromagnetic spin-exchange interactions (self-defocusing case), or attractive interatomic interactions and ferromagnetic spin-exchange interactions (self-focusing case). The IST for this system was first presented by Ieda et al. (2007) , using a different approach. In our formulation, both the direct and the inverse problems are posed in terms of a suitable uniformization variable which allows to develop the IST on the standard complex plane, instead of a two-sheeted Riemann surface or the cut plane with discontinuities along the cuts. Analyticity of the scattering eigenfunctions and scattering data, symmetries, properties of the discrete spectrum, and asymptotics are derived. The inverse problem is posed as a Riemann-Hilbert problem for the eigenfunctions, and the reconstruction formula of the potential in terms of eigenfunctions and scattering data is provided. In addition, the general behavior of the soliton solutions is analyzed in detail in the 2 × 2 self-focusing case, including some special solutions not previously discussed in the literature.

Electronic structure and dissociation curves for the ground states of Tl/sub 2/ and Tl/sub 2//sup +/ from relativistic effective potential calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Christiansen, P.A.; Pitzer, K.S.

The dissociation curves for the ground states of Tl/sub 2/ and Tl/sub 2//sup +/ were computed using a generalization of the molecular relativistic ..omega..--..omega.. coupling formalism of Lee, Ermler, and Pitzer. Relativistic effects, as represented by the Dirac equation, were introduced using effective potentials generated from atomic Dirac--nFock wave functions using a generalization of the improved effective potential formulation of Christiansen, Lee, and Pitzer. Our calculations show that the ground state of Tl/sub 2//sup +/ is 1/2/sub g/ with computed D/sub e/ and R/sub e/ values of 0.58 eV and 3.84 A. For Tl/sub 2/ we find that the groundmore » state is 0/sub u//sup -/ but the 0/sub g//sup +/ and the 1/sub u/ states are only slightly higher in energy; the potential curves for these states are repulsive to about 3.5 A and then essentially flat beyond that radius. While corrections for correlation will increase D/sub e/ somewhat, Tl/sub 2/ is only weakly bound in any of these states which dissociate to normal atoms. The cause is undoubtedly related to the large spin-orbit splitting between the 6p/sub 1/2/ and 6p/sub 3/2/ thallium spinors.« less

Solitary waves in the nonlinear Dirac equation in the presence of external driving forces

DOE PAGES

Mertens, Franz G.; Cooper, Fred; Quintero, Niurka R.; ...

2016-01-05

In this paper, we consider the nonlinear Dirac (NLD) equation in (1 + 1) dimensions with scalar–scalar self interaction g 2/κ + 1 (Ψ¯Ψ) κ + 1 in the presence of external forces as well as damping of the form f(x) - iμγ 0Ψ, where both f and Ψ are two-component spinors. We develop an approximate variational approach using collective coordinates (CC) for studying the time dependent response of the solitary waves to these external forces. This approach predicts intrinsic oscillations of the solitary waves, i.e. the amplitude, width and phase all oscillate with the same frequency. The translational motionmore » is also affected, because the soliton position oscillates around a mean trajectory. For κ = 1 we solve explicitly the CC equations of the variational approximation for slow moving solitary waves in a constant external force without damping and find reasonable agreement with solving numerically the CC equations. Finally, we then compare the results of the variational approximation with no damping with numerical simulations of the NLD equation for κ = 1, when the components of the external force are of the form f j = r j exp(–iΚx) and again find agreement if we take into account a certain linear excitation with specific wavenumber that is excited together with the intrinsic oscillations such that the momentum in a transformed NLD equation is conserved.« less

Dominant Majorana bound energy and critical current enhancement in ferromagnetic-superconducting topological insulator

NASA Astrophysics Data System (ADS)

Khezerlou, Maryam; Goudarzi, Hadi; Asgarifar, Samin

2017-03-01

Among the potential applications of topological insulators, we theoretically study the coexistence of proximity-induced ferromagnetic and superconducting orders in the surface states of a 3-dimensional topological insulator. The superconducting electron-hole excitations can be significantly affected by the magnetic order induced by a ferromagnet. In one hand, the surface state of the topological insulator, protected by the time-reversal symmetry, creates a spin-triplet and, on the other hand, magnetic order causes to renormalize the effective superconducting gap. We find Majorana mode energy along the ferromagnet/superconductor interface to sensitively depend on the magnitude of magnetization m zfs from superconductor region, and its slope around perpendicular incidence is steep with very low dependency on m zfs . The superconducting effective gap is renormalized by a factor η( m zfs ), and Andreev bound state in ferromagnet-superconductor/ferromagnet/ferromagnet-superconductor (FS/F/FS) Josephson junction is more sensitive to the magnitude of magnetizations of FS and F regions. In particular, we show that the presence of m zfs has a noticeable impact on the gap opening in Andreev bound state, which occurs in finite angle of incidence. This directly results in zero-energy Andreev state being dominant. By introducing the proper form of corresponding Dirac spinors for FS electron-hole states, we find that via the inclusion of m zfs , the Josephson supercurrent is enhanced and exhibits almost abrupt crossover curve, featuring the dominant zero-energy Majorana bound states.

GRASP92: a package for large-scale relativistic atomic structure calculations

NASA Astrophysics Data System (ADS)

Parpia, F. A.; Froese Fischer, C.; Grant, I. P.

2006-12-01

Program summaryTitle of program: GRASP92 Catalogue identifier: ADCU_v1_1 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADCU_v1_1 Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions: no Programming language used: Fortran Computer: IBM POWERstation 320H Operating system: IBM AIX 3.2.5+ RAM: 64M words No. of lines in distributed program, including test data, etc.: 65 224 No of bytes in distributed program, including test data, etc.: 409 198 Distribution format: tar.gz Catalogue identifier of previous version: ADCU_v1_0 Journal reference of previous version: Comput. Phys. Comm. 94 (1996) 249 Does the new version supersede the previous version?: Yes Nature of problem: Prediction of atomic spectra—atomic energy levels, oscillator strengths, and radiative decay rates—using a 'fully relativistic' approach. Solution method: Atomic orbitals are assumed to be four-component spinor eigenstates of the angular momentum operator, j=l+s, and the parity operator Π=βπ. Configuration state functions (CSFs) are linear combinations of Slater determinants of atomic orbitals, and are simultaneous eigenfunctions of the atomic electronic angular momentum operator, J, and the atomic parity operator, P. Lists of CSFs are either explicitly prescribed by the user or generated from a set of reference CSFs, a set of subshells, and rules for deriving other CSFs from these. Approximate atomic state functions (ASFs) are linear combinations of CSFs. A variational functional may be constructed by combining expressions for the energies of one or more ASFs. Average level (AL) functionals are weighted sums of energies of all possible ASFs that may be constructed from a set of CSFs; the number of ASFs is then the same as the number, n, of CSFs. Optimal level (OL) functionals are weighted sums of energies of some subset of ASFs; the GRASP92 package is optimized for this latter class of functionals. The composition of an ASF in terms of CSFs sharing the same quantum numbers is determined using the configuration-interaction (CI) procedure that results upon varying the expansion coefficients to determine the extremum of a variational functional. Radial functions may be determined by numerically solving the multiconfiguration Dirac-Fock (MCDF) equations that result upon varying the orbital radial functions or some subset thereof so as to obtain an extremum of the variational functional. Radial wavefunctions may also be determined using a screened hydrogenic or Thomas-Fermi model, although these schemes generally provide initial estimates for MCDF self-consistent-field (SCF) calculations. Transition properties for pairs of ASFs are computed from matrix elements of multipole operators of the electromagnetic field. All matrix elements of CSFs are evaluated using the Racah algebra. Reasons for the new version: During recent studies using the general relativistic atomic structure package (GRASP92), several errors were found, some of which might have been present already in the earlier GRASP92 version (program ABJN_v1_0, Comput. Phys. Comm. 55 (1989) 425). These errors were reported and discussed by Froese Fischer, Gaigalas, and Ralchenko in a separate publication [C. Froese Fischer, G. Gaigalas, Y. Ralchenko, Comput. Phys. Comm. 175 (2006) 738-744. [7

Hybrid matrix method for stable numerical analysis of the propagation of Dirac electrons in gapless bilayer graphene superlattices

NASA Astrophysics Data System (ADS)

Briones-Torres, J. A.; Pernas-Salomón, R.; Pérez-Álvarez, R.; Rodríguez-Vargas, I.

2016-05-01

Gapless bilayer graphene (GBG), like monolayer graphene, is a material system with unique properties, such as anti-Klein tunneling and intrinsic Fano resonances. These properties rely on the gapless parabolic dispersion relation and the chiral nature of bilayer graphene electrons. In addition, propagating and evanescent electron states coexist inherently in this material, giving rise to these exotic properties. In this sense, bilayer graphene is unique, since in most material systems in which Fano resonance phenomena are manifested an external source that provides extended states is required. However, from a numerical standpoint, the presence of evanescent-divergent states in the eigenfunctions linear superposition representing the Dirac spinors, leads to a numerical degradation (the so called Ωd problem) in the practical applications of the standard Coefficient Transfer Matrix (K) method used to study charge transport properties in Bilayer Graphene based multi-barrier systems. We present here a straightforward procedure based in the hybrid compliance-stiffness matrix method (H) that can overcome this numerical degradation. Our results show that in contrast to standard matrix method, the proposed H method is suitable to study the transmission and transport properties of electrons in GBG superlattice since it remains numerically stable regardless the size of the superlattice and the range of values taken by the input parameters: the energy and angle of the incident electrons, the barrier height and the thickness and number of barriers. We show that the matrix determinant can be used as a test of the numerical accuracy in real calculations.

The Self-Evolving Cosmos: A Phenomenological Approach to Nature's Unity-in-Diversity

NASA Astrophysics Data System (ADS)

Rosen, Steven M.

ch. 1. Introduction: individuation and the quest for unity -- ch. 2. The obstacle to unification in modern physics. 2.1. Introduction. 2.2. Does contemporary mathematical physics actually depart from the classical formulation? -- ch. 3. The phenomenological challenge to the classical formula -- ch. 4. Topological phenomenology. 4.1. Introduction. 4.2. Phenomenological intuition, topology, and the Klein bottle. 4.3. The physical significance of the Klein bottle -- ch. 5. The dimensional family of topological spinors. 5.1. Generalization of intuitive topology. 5.2. Topodimensional spin matrix -- ch. 6. Basic principles of dimensional transformation. 6.1. Synsymmetry and the self-transformation of space. 6.2. From symmetry breaking to dimensional generation. 6.3. The three basic stages of dimensional generation. 6.4. Kleinian topogeny -- ch. 7. Waves carrying waves: the co-evolution of lifeworlds -- ch. 8. The forces of nature. 8.1. The phenomenon of light. 8.2. Phenomenological Kaluza-Klein theory. 8.3. Summary comparison of conventional and topo-phenomenological approaches to Kaluza-Klein theory -- ch. 9. Cosmogony, symmetry, and phenomenological intuition. 9.1. Conventional view of the evolving cosmos. 9.2. The problem of symmetry. 9.3. A new kind of clarity -- ch. 10. The self-evolving cosmos. 10.1. Introduction to the cosmogonic matrix. 10.2. Overview of cosmic evolution. 10.3. The role of the fermions in dimensional generation. 10.4. Projective stages of cosmogony: dimensional divergence. 10.5. Proprioceptive stages of cosmogony: dimensional convergence. 10.6. Conclusion: wider horizons of cosmic evolution -- ch. 11. The psychophysics of cosmogony. 11.1. Psychical aspects of the fundamental particles. 11.2. Toward a reflexive physics. 11.3. Concretization of the self-evolving cosmos.

Soft-collinear supersymmetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cohen, Timothy; Elor, Gilly; Larkoski, Andrew J.

Soft-Collinear E ective Theory (SCET) is a framework for modeling the infrared structure of theories whose long distance behavior is dominated by soft and collinear divergences. This paper demonstrates that SCET can be made compatible with supersymmetry (SUSY). Explicitly, the e ective Lagrangian for N = 1 SUSY Yang-Mills is constructed and shown to be a complete description for the infrared of this model. For contrast, we also construct the e ective Lagrangian for chiral SUSY theories with Yukawa couplings, speci cally the single avor Wess-Zumino model. Only a subset of the infrared divergences are reproduced by the Lagrangian |more » to account for the complete low energy description requires the inclusion of local operators. SCET is formulated by expanding elds along a light-like direction and then subsequently integrating out degrees-of-freedom that are away from the light-cone. De ning the theory with respect to a speci c frame obfuscates Lorentz invariance | given that SUSY is a space-time symmetry, this presents a possible obstruction. The cleanest language with which to expose the congruence between SUSY and SCET requires exploring two novel formalisms: collinear fermions as two-component Weyl spinors, and SCET in light-cone gauge. By expressing SUSY Yang- Mills in \\collinear superspace", a slice of superspace derived by integrating out half the fermionic coordinates, the light-cone gauge SUSY SCET theory can be written in terms of super elds. As a byproduct, bootstrapping up to the full theory yields the rst algorithmic approach for determining the SUSY Yang-Mills on-shell superspace action. As a result, this work paves the way toward discovering the e ective theory for the collinear limit of N = 4 SUSY Yang-Mills.« less

Constraining neutrino masses, the cosmological constant and BSM physics from the weak gravity conjecture

NASA Astrophysics Data System (ADS)

Ibáñez, Luis E.; Martín-Lozano, Víctor; Valenzuela, Irene

2017-11-01

It is known that there are AdS vacua obtained from compactifying the SM to 2 or 3 dimensions. The existence of such vacua depends on the value of neutrino masses through the Casimir effect. Using the Weak Gravity Conjecture, it has been recently argued by Ooguri and Vafa that such vacua are incompatible with the SM embedding into a consistent theory of quantum gravity. We study the limits obtained for both the cosmological constant Λ4 and neutrino masses from the absence of such dangerous 3D and 2D SM AdS vacua. One interesting implication is that Λ4 is bounded to be larger than a scale of order m ν 4 , as observed experimentally. Interestingly, this is the first argument implying a non-vanishing Λ4 only on the basis of particle physics, with no cosmological input. Conversely, the observed Λ4 implies strong constraints on neutrino masses in the SM and also for some BSM extensions including extra Weyl or Dirac spinors, gravitinos and axions. The upper bounds obtained for neutrino masses imply (for fixed neutrino Yukawa and Λ4) the existence of upper bounds on the EW scale. In the case of massive Majorana neutrinos with a see-saw mechanism associated to a large scale M ≃ 1010 - 14 GeV and Y ν1 ≃ 10-3, one obtains that the EW scale cannot exceed M EW ≲ 102 - 104 GeV. From this point of view, the delicate fine-tuning required to get a small EW scale would be a mirage, since parameters yielding higher EW scales would be in the swampland and would not count as possible consistent theories. This would bring a new perspective into the issue of the EW hierarchy.

Soft-collinear supersymmetry

DOE PAGES

Cohen, Timothy; Elor, Gilly; Larkoski, Andrew J.

2017-03-03

Soft-Collinear E ective Theory (SCET) is a framework for modeling the infrared structure of theories whose long distance behavior is dominated by soft and collinear divergences. This paper demonstrates that SCET can be made compatible with supersymmetry (SUSY). Explicitly, the e ective Lagrangian for N = 1 SUSY Yang-Mills is constructed and shown to be a complete description for the infrared of this model. For contrast, we also construct the e ective Lagrangian for chiral SUSY theories with Yukawa couplings, speci cally the single avor Wess-Zumino model. Only a subset of the infrared divergences are reproduced by the Lagrangian |more » to account for the complete low energy description requires the inclusion of local operators. SCET is formulated by expanding elds along a light-like direction and then subsequently integrating out degrees-of-freedom that are away from the light-cone. De ning the theory with respect to a speci c frame obfuscates Lorentz invariance | given that SUSY is a space-time symmetry, this presents a possible obstruction. The cleanest language with which to expose the congruence between SUSY and SCET requires exploring two novel formalisms: collinear fermions as two-component Weyl spinors, and SCET in light-cone gauge. By expressing SUSY Yang- Mills in \\collinear superspace", a slice of superspace derived by integrating out half the fermionic coordinates, the light-cone gauge SUSY SCET theory can be written in terms of super elds. As a byproduct, bootstrapping up to the full theory yields the rst algorithmic approach for determining the SUSY Yang-Mills on-shell superspace action. As a result, this work paves the way toward discovering the e ective theory for the collinear limit of N = 4 SUSY Yang-Mills.« less

FFT-split-operator code for solving the Dirac equation in 2+1 dimensions

NASA Astrophysics Data System (ADS)

Mocken, Guido R.; Keitel, Christoph H.

2008-06-01

The main part of the code presented in this work represents an implementation of the split-operator method [J.A. Fleck, J.R. Morris, M.D. Feit, Appl. Phys. 10 (1976) 129-160; R. Heather, Comput. Phys. Comm. 63 (1991) 446] for calculating the time-evolution of Dirac wave functions. It allows to study the dynamics of electronic Dirac wave packets under the influence of any number of laser pulses and its interaction with any number of charged ion potentials. The initial wave function can be either a free Gaussian wave packet or an arbitrary discretized spinor function that is loaded from a file provided by the user. The latter option includes Dirac bound state wave functions. The code itself contains the necessary tools for constructing such wave functions for a single-electron ion. With the help of self-adaptive numerical grids, we are able to study the electron dynamics for various problems in 2+1 dimensions at high spatial and temporal resolutions that are otherwise unachievable. Along with the position and momentum space probability density distributions, various physical observables, such as the expectation values of position and momentum, can be recorded in a time-dependent way. The electromagnetic spectrum that is emitted by the evolving particle can also be calculated with this code. Finally, for planning and comparison purposes, both the time-evolution and the emission spectrum can also be treated in an entirely classical relativistic way. Besides the implementation of the above-mentioned algorithms, the program also contains a large C++ class library to model the geometric algebra representation of spinors that we use for representing the Dirac wave function. This is why the code is called "Dirac++". Program summaryProgram title: Dirac++ or (abbreviated) d++ Catalogue identifier: AEAS_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAS_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 474 937 No. of bytes in distributed program, including test data, etc.: 4 128 347 Distribution format: tar.gz Programming language: C++ Computer: Any, but SMP systems are preferred Operating system: Linux and MacOS X are actively supported by the current version. Earlier versions were also tested successfully on IRIX and AIX Number of processors used: Generally unlimited, but best scaling with 2-4 processors for typical problems RAM: 160 Megabytes minimum for the examples given here Classification: 2.7 External routines: FFTW Library [3,4], Gnu Scientific Library [5], bzip2, bunzip2 Nature of problem: The relativistic time evolution of wave functions according to the Dirac equation is a challenging numerical task. Especially for an electron in the presence of high intensity laser beams and/or highly charged ions, this type of problem is of considerable interest to atomic physicists. Solution method: The code employs the split-operator method [1,2], combined with fast Fourier transforms (FFT) for calculating any occurring spatial derivatives, to solve the given problem. An autocorrelation spectral method [6] is provided to generate a bound state for use as the initial wave function of further dynamical studies. Restrictions: The code in its current form is restricted to problems in two spatial dimensions. Otherwise it is only limited by CPU time and memory that one can afford to spend on a particular problem. Unusual features: The code features dynamically adapting position and momentum space grids to keep execution time and memory requirements as small as possible. It employs an object-oriented approach, and it relies on a Clifford algebra class library to represent the mathematical objects of the Dirac formalism which we employ. Besides that it includes a feature (typically called "checkpointing") which allows the resumption of an interrupted calculation. Additional comments: Along with the program's source code, we provide several sample configuration files, a pre-calculated bound state wave function, and template files for the analysis of the results with both MatLab and Igor Pro. Running time: Running time ranges from a few minutes for simple tests up to several days, even weeks for real-world physical problems that require very large grids or very small time steps. References:J.A. Fleck, J.R. Morris, M.D. Feit, Time-dependent propagation of high energy laser beams through the atmosphere, Appl. Phys. 10 (1976) 129-160. R. Heather, An asymptotic wavefunction splitting procedure for propagating spatially extended wavefunctions: Application to intense field photodissociation of H +2, Comput. Phys. Comm. 63 (1991) 446. M. Frigo, S.G. Johnson, FFTW: An adaptive software architecture for the FFT, in: Proceedings of the IEEE International Conference on Acoustics, Speech and Signal Processing, vol. 3, IEEE, 1998, pp. 1381-1384. M. Frigo, S.G. Johnson, The design and implementation of FFTW3, in: Proceedings of the IEEE, vol. 93, IEEE, 2005, pp. 216-231. URL: http://www.fftw.org/. M. Galassi, J. Davies, J. Theiler, B. Gough, G. Jungman, M. Booth, F. Rossi, GNU Scientific Library Reference Manual, second ed., Network Theory Limited, 2006. URL: http://www.gnu.org/software/gsl/. M.D. Feit, J.A. Fleck, A. Steiger, Solution of the Schrödinger equation by a spectral method, J. Comput. Phys. 47 (1982) 412-433.

Book Review:

NASA Astrophysics Data System (ADS)

Fulling, S. A.

2006-05-01

Bryce Seligman DeWitt (1923 2004), a friend and mentor to many, was a towering figure in the development of the quantum theories of gravity and gauge fields. To appreciate his uniqueness, one must recall the history through which he lived. From DeWitt's birth date through 1965, general relativity (GR) was considered to have so few empirically testable predictions that its practitioners in English-speaking countries were largely banished to mathematics departments. When the discoveries of cosmological background radiation, quasars and pulsars made it clear that GR does model important science at astronomical scales, the theory still appeared remote from the microcosmic concerns of most research physicists. Every course on elementary-particle physics began by listing the four fundamental forces of nature; then the lecturer would cross off the line 'gravitational' and say 'we will have no more to say about that one'. As recently as 1980, high-energy theorists lecturing on phase transitions in the early universe often started their timelines with a cartoon of a dragon to represent the unknowable initial subnanosecond. The isolation of GR from the rest of theoretical physics was intensified by the special nature of its mathematical tools. Particle physicists could recognize that condensed-matter people were doing quantum field theory; nuclear and molecular physicists used the same quantum mechanics. In the early days, the heavily indexed tensors of GR betokened a kinship with continuum mechanics (similarly exiled to engineering departments), but when relativists fell under the spell of index-free differential forms and algebraic topology, their isolation became complete. But only briefly: by around 1976 non-Abelian gauge theories had become the core of the standard model even as they were increasingly explicitly expounded in terms of the geometry and topology of Lie groups and fibre bundles. By 1985 the superstring revolution was under way, and soon the professors were saying that gravity was not only an honourable member of the forces of nature, but ultimately the source of them all. It has become a cliche that the unification of relativity with quantum theory is the central problem of contemporary physics. In the 1950s, before strings, non-Abelian monopoles, or even quasars, Bryce DeWitt was applying the quantum-field-theoretical methods and conceptual framework of his mentor, Julian Schwinger, to gravity. His central insight was that the conceptual and technical problems of quantum gravity were closely analogous to those of gauge theories. He developed a unified, relentlessly abstract, and highly personal vision of the fundamentals of physical theory. It was, and is, expressed in idiosyncratic and condensed notation often different from the languages of mainstream field theorists, traditional relativists, and mathematicians alike. In short, he has never been easy reading. His ideas were systematically presented in famous lecture series at the Les Houches summer schools on Relativity, Groups and Topology in 1963 [1] and 1983 [2], the book Supermanifolds [3], and a number of (relatively) shorter expositions that have been widely read. By the middle 1970s the methods that he had developed mainly for gravity were widely recognized as very useful for Yang Mills gauge theories, and his work had become part of the mainstream. Now, another 20 years after the second Les Houches, we have this final testament of Bryce DeWitt's ideas. At over 1000 pages in two volumes in a fabric-covered slipcase, it is the sort of work usually described as 'magisterial' (meaning, perhaps, 'no one has yet succeeded in reading it all the way through'). Over the years, of course, DeWitt learned many new things and thought of ways to say the old things better. Accordingly, the new books consist of reworkings of the most important parts of the older writings together with some new material. Oxford University Press is to be thanked and congratulated for the care it has lavished on this set, which is an important monument and reference but presumably not a moneymaker. Every university library must buy it, but probably few individuals will, at least not in the near term when most of those with the seniority (i.e., cash) to make the purchase already own, or have read, the Les Houches lectures. What remains to be seen is to what extent a later generation will discover it as a valuable resource. Parts I and II develop the basic classical and quantum kinematics of fields and other dynamical systems. The presentation is conducted in the utmost generality, allowing for dynamical quantities that may be anticommuting (supernumbers) and theories subject to the most general possible gauge symmetry— in fact, such symmetries are called 'invariant flows' to emphasize that they may not form a gauge group in the conventional sense. The basic ingredients are action functionals and the Peierls bracket, a manifestly covariant replacement for the Poisson bracket and equal-time commutation relations. Nothing was more central to the DeWitt gospel than these, and the book begins with a paragraph of condemnation of Hamiltonians and canonical formulations with constraints as dysfunctional nineteenth-century baggage. For DeWitt the logical progression is Peierls bracket → Schwinger action principle → Feynman functional integral although he points out that the historical development was in the opposite order. The word 'global' in the title, presumably chosen to avoid duplicating the second Les Houches lectures, refers to this overall framework.The word is somewhat misleading, since in many respects DeWitt's work entails a concentration on local over global quantities. For example, chapter 2 states forcefully that local gauge symmetries are both more fundamental and more ubiquitous than global symmetries. It must be pointed out that the Peierls Schwinger DeWitt approach, despite some advantages over initial-value formulations, has some troubles of its own. In particular, it has never completely escaped from the arena of scattering theory, the paradigm of conventional particle physics. One is naturally led to study matrix elements between an 'in-vacuum' and an 'out-vacuum' though such concepts are murky in situations, such as big bangs and black holes, where the ambient geometry is not asymptotically static in the far past and future. The newest material in the treatise appears in two chapters in part II devoted to the interpretation of quantum theory, incorporating some unpublished work of David Deutsch on the meaning of probability in physics. Such discussions are unavoidably polemical; DeWitt takes a firm stand ('Everett's ['many worlds'] interpretation has been adopted by the author out of practical necessity: he knows of no other [acceptable one]'), but he acknowledges that 'each physicist has his own manner of understanding quantum mechanics', and the philosophical differences have little import for how theories are applied in practice. In the end DeWitt's many-world theory comes out very similar to the more recent 'decoherent histories' approach, which (in some versions, at least) attributes physical reality to quantities whose measurements can be predicted with certainty—thereby having as much kinship with hidden-variable theories as with the extreme Everett view. I recall a conversation with Bryce in which he said (in paraphrase) 'there is a deeper reality underneath the quantum reality. [In that sense Einstein, Podolsky and Rosen were right.] But it is not the classical reality. [That is, a naive hidden-variable picture does not apply at the microscopic level.]' This occurred probably in the late 1970s, long after DeWitt became a public partisan of the Everett interpretation and long before this book, so I do not believe that it represents a wavering of his faith in many worlds, just a nuance in what that meant to him. Parts III through V apply the formalism in depth to successively more difficult classes of systems: quantum mechanics, linear (free) fields, and interacting fields. DeWitt's characteristic tools of effective actions, heat kernels, and ghost fields are developed. Chapters 26 and 31 outline new approaches developed in collaboration with DeWitt's recent students C Molina-Paris and C Y Wang, respectively. The first of these is a ghost-free formulation of gauge theory built on ideas of G A Vilkovisky. The second is a systematic attempt (following J Schwinger, L V Keldysh, and others) to replace the in-out matrix elements by expectation values in a single (initial) state. Most of parts VI and VII consist of special topics, such as anomalies, particle creation by external fields, Unruh acceleration temperature, black holes, and Euclideanization. Chapter 30, on black holes and Hawking radiation, will be very familiar to readers of DeWitt's influential review article [4]. Chapter 28, on anomalies, makes a careful distinction (missing from many treatments) between 'critical' anomalies, which render equations of motion inconsistent in the (would-be) quantum theory, and harmless anomalies that merely invalidate predictions that would classically follow from certain symmetries. The trace anomalies in the stress tensor of matter and the axial-current anomaly in quantum electrodynamics are harmless. Examples of critical anomalies are the chiral anomaly of a spinor field coupled to a non-Abelian gauge field and the anomaly in the conservation law of the stress tensor of certain pathological theories [5]. DeWitt's chapter calculates the trace and chiral anomalies in detail. The axial anomaly is mentioned only in a one-line summary (and not defined or indexed—generally speaking, I found the book's long index surprisingly unhelpful), and the Alvarez Witten anomaly is not mentioned at all. The last two chapters of part VII treat the most important particular quantum field theories. Chapter 34 develops many of the textbook predictions of quantum eletrodynamics from DeWitt's starting point. Chapter 35 covers Yang Mills fields and quantum gravity. The discussion of gravity is surprisingly brief, in view of DeWitt's lifelong preoccupation with that subject. One gathers that he came to accept that quantization of ordinary GR was a nonrenormalizable dead end and he did not feel able to delve into modern alternatives such as string theory. He rejects renormalizable fourth-order modifications of four-dimensional gravity because he could not stomach unfriendly ghosts (states of negative norm or unboundedly negative energy) nor the technical difficulties of integrating such theories into the functional-integral formalism (see pp 866 7). Finally, there is part VIII, entitled 'Examples. Simple Exercises in the Use of the Global Formalism'. It consists of 25 short chapters numbered separately from those of the main text. The preface recommends reading these and the main text in parallel. Most valuable in my opinion is a string of successively more complicated fermionic models, from which one can, with effort, come to understand the book's concern with anticommuting quantities. Hidden in an appendix (p 1001) is a crucial motivational paragraph: Super Hilbert spaces are generalizations of ordinary Hilbert spaces, designed so as to enable one to consider quantum systems with supernumber-valued parameters (e.g., a-type external sources) which, themselves, are introduced in order to present, in a compact algebraic way, certain relationships between real physical amplitudes. Real physics is restricted to the ordinary Hilbert space that fits inside the super Hilbert space. That is, anticommuting classical quantities (a-numbers) serve to fit anticommuting quantum fields naturally into the formalism of actions and functional integrals. Ultimately, the quantum theory of a conventional fermion field is expressible in the same spinors and Dirac matrices as before supersymmetry was invented. On the other hand, since products of two a-numbers are commuting objects, the full algebra of supernumbers includes an infinite hierarchy of positive even degree in addition to the ordinary real or complex numbers at degree 0 and the anticommuting things of odd degree. DeWitt calls all the even supernumbers 'c-numbers'; quantities of degree 0 are 'body' and those of all positive degrees are 'soul'. For consistency this parallel spirit world must be carried along even when the theory is purely bosonic; but it can be shown that the c-number soul makes no net contribution to the integrals that arise in field-theoretic calculations, and in the end it seems that the reader is not misled by interpreting 'c-number' in the traditional way in most contexts. This seems a high price to pay for the existence of classical fermion fields. The supernumber examples continue up through spin-3/2 fields, but there is no discussion anywhere of full supergravity. As part VIII progresses, the examples become less pedagogical and more a catalogue of formulas for particular field theories. Filling in the details of these calculations will indeed be strenuous exercises for the diligent student. Is this treatise a textbook, a reference, or something else? Certainly it is not intended for a beginner. The author says that it is 'in no sense a reference book', that it is intended 'to tie up loose ends', and that 'the selection of topics is idiosyncratic'. Bibliographical citations are sparse, although scrupulous in giving credit for the ideas of others. As I've noted, often one is surprised at what topics are not treated. Nevertheless, this wide-ranging and deep picture of the fundamental structure of our universe is awe-inspiring. Bryce DeWitt was uncommonly lucky in being able to complete a comprehensive statement of his world view right at the end of his life. We, also, are lucky to have it. We and our successors should revere it, even as we sift it critically for those ideas that should survive as principles of the theoretical physics of the future. References DeWitt B 1964 Dynamical theory of groups and fields Relativity, Groups and Topology ed C DeWitt and B DeWitt (London: Gordon and Breach) pp 585 820 (Republished as DeWitt B S 1965 Dynamical Theory of Groups and Fields (London: Gordon and Breach)) DeWitt B 1984 The spacetime approach to quantum field theory Relativity, Groups and Topology II ed BS DeWitt and R Stora (Amersterdam: North-Holland) pp381 738 DeWitt B 1984 Supermanifolds (Cambridge: Cambridge University Press) DeWitt B 1975 Phys. Rep. 19 295 357 Alvarez-Gaumé L and Witten E 1983 Nucl. Phys. B 234 269 330

Universal Themes of Bose-Einstein Condensation

NASA Astrophysics Data System (ADS)

Proukakis, Nick P.; Snoke, David W.; Littlewood, Peter B.

2017-04-01

Foreword; List of contributors; Preface; Part I. Introduction: 1. Universality and Bose-Einstein condensation: perspectives on recent work D. W. Snoke, N. P. Proukakis, T. Giamarchi and P. B. Littlewood; 2. A history of Bose-Einstein condensation of atomic hydrogen T. Greytak and D. Kleppner; 3. Twenty years of atomic quantum gases: 1995-2015 W. Ketterle; 4. Introduction to polariton condensation P. B. Littlewood and A. Edelman; Part II. General Topics: Editorial notes; 5. The question of spontaneous symmetry breaking in condensates D. W. Snoke and A. J. Daley; 6. Effects of interactions on Bose-Einstein condensation R. P. Smith; 7. Formation of Bose-Einstein condensates M. J. Davis, T. M. Wright, T. Gasenzer, S. A. Gardiner and N. P. Proukakis; 8. Quenches, relaxation and pre-thermalization in an isolated quantum system T. Langen and J. Schmiedmayer; 9. Ultracold gases with intrinsic scale invariance C. Chin; 10. Berezinskii-Kosterlitz-Thouless phase of a driven-dissipative condensate N. Y. Kim, W. H. Nitsche and Y. Yamamoto; 11. Superfluidity and phase correlations of driven dissipative condensates J. Keeling, L. M. Sieberer, E. Altman, L. Chen, S. Diehl and J. Toner; 12. BEC to BCS crossover from superconductors to polaritons A. Edelman and P. B. Littlewood; Part III. Condensates in Atomic Physics: Editorial notes; 13. Probing and controlling strongly correlated quantum many-body systems using ultracold quantum gases I. Bloch; 14. Preparing and probing chern bands with cold atoms N. Goldman, N. R. Cooper and J. Dalibard; 15. Bose-Einstein condensates in artificial gauge fields L. J. LeBlanc and I. B. Spielman; 16. Second sound in ultracold atomic gases L. Pitaevskii and S. Stringari; 17. Quantum turbulence in atomic Bose-Einstein condensates N. G. Parker, A. J. Allen, C. F. Barenghi and N. P. Proukakis; 18. Spinor-dipolar aspects of Bose-Einstein condensation M. Ueda; Part IV. Condensates in Condensed Matter Physics: Editorial notes; 19. Bose-Einstein condensation of photons and grand-canonical condensate fluctuations J. Klaers and M. Weitz; 20. Laser operation and Bose-Einstein condensation: analogies and differences A. Chiocchetta, A. Gambassi and I. Carusotto; 21. Vortices in resonant polariton condensates in semiconductor microcavities D. N. Krizhanovskii, K. Guda, M. Sich, M. S. Skolnick, L. Dominici and D. Sanvitto; 22. Optical control of polariton condensates G. Christmann, P. G. Savvidis and J. J. Baumberg; 23. Disorder, synchronization and phase-locking in non-equilibrium Bose-Einstein condensates P. R. Eastham and B. Rosenow; 24. Collective topological excitations in 1D polariton quantum fluids H. Terças, D. D. Solnyshkov and G. Malpuech; 25. Microscopic theory of Bose-Einstein condensation of magnons at room temperature H. Salman, N. G. Berloff and S. O. Demokritov; 26. Spintronics and magnon Bose-Einstein condensation R. A. Duine, A. Brataas, S. A. Bender and Y. Tserkovnyak; 27. Spin-superfluidity and spin-current mediated non-local transport H. Chen and A. H. MacDonald; 28. Bose-Einstein condensation in quantum magnets C. Kollath, T. Giamarchi and C. Rüegg; Part V. Condensates in Astrophysics and Cosmology: Editorial notes; 29. Bose-Einstein condensates in neutron stars C. J. Pethick, T. Schäfer and A. Schwenk; 30. A simulated cosmological metric: the superfluid 3He condensate G. R. Pickett; 31. Cosmic axion Bose-Einstein condensation N. Banik and P. Sikivie; 32. Graviton BECs: a new approach to quantum gravity G. Dvali and C. Gomez; Universal Bose-Einstein condensation workshop; Index.

Combining the spin-separated exact two-component relativistic Hamiltonian with the equation-of-motion coupled-cluster method for the treatment of spin-orbit splittings of light and heavy elements.

PubMed

Cao, Zhanli; Li, Zhendong; Wang, Fan; Liu, Wenjian

2017-02-01

The spin-separated exact two-component (X2C) relativistic Hamiltonian [sf-X2C+so-DKHn, J. Chem. Phys., 2012, 137, 154114] is combined with the equation-of-motion coupled-cluster method with singles and doubles (EOM-CCSD) for the treatment of spin-orbit splittings of open-shell molecular systems. Scalar relativistic effects are treated to infinite order from the outset via the spin-free part of the X2C Hamiltonian (sf-X2C), whereas the spin-orbit couplings (SOC) are handled at the CC level via the first-order Douglas-Kroll-Hess (DKH) type of spin-orbit operator (so-DKH1). Since the exponential of single excitations, i.e., exp(T 1 ), introduces sufficient spin orbital relaxations, the inclusion of SOC at the CC level is essentially the same in accuracy as the inclusion of SOC from the outset in terms of the two-component spinors determined variationally by the sf-X2C+so-DKH1 Hamiltonian, but is computationally more efficient. Therefore, such an approach (denoted as sf-X2C-EOM-CCSD(SOC)) can achieve uniform accuracy for the spin-orbit splittings of both light and heavy elements. For light elements, the treatment of SOC can even be postponed until the EOM step (denoted as sf-X2C-EOM(SOC)-CCSD), so as to further reduce the computational cost. To reveal the efficacy of sf-X2C-EOM-CCSD(SOC) and sf-X2C-EOM(SOC)-CCSD, the spin-orbit splittings of the 2 Π states of monohydrides up to the sixth row of the periodic table are investigated. The results show that sf-X2C-EOM-CCSD(SOC) predicts very accurate results (within 5%) for elements up to the fifth row, whereas sf-X2C-EOM(SOC)-CCSD is useful only for light elements (up to the third row but with some exceptions). For comparison, the sf-X2C-S-TD-DFT-SOC approach [spin-adapted open-shell time-dependent density functional theory, Mol. Phys., 2013, 111, 3741] is applied to the same systems. The overall accuracy (1-10%) is satisfactory.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Livine, Etera R.

We introduce the set of framed (convex) polyhedra with N faces as the symplectic quotient C{sup 2N}//SU(2). A framed polyhedron is then parametrized by N spinors living in C{sup 2} satisfying suitable closure constraints and defines a usual convex polyhedron plus extra U(1) phases attached to each face. We show that there is a natural action of the unitary group U(N) on this phase space, which changes the shape of faces and allows to map any (framed) polyhedron onto any other with the same total (boundary) area. This identifies the space of framed polyhedra to the Grassmannian space U(N)/ (SU(2)×U(N−2)).more » We show how to write averages of geometrical observables (polynomials in the faces' area and the angles between them) over the ensemble of polyhedra (distributed uniformly with respect to the Haar measure on U(N)) as polynomial integrals over the unitary group and we provide a few methods to compute these integrals systematically. We also use the Itzykson-Zuber formula from matrix models as the generating function for these averages and correlations. In the quantum case, a canonical quantization of the framed polyhedron phase space leads to the Hilbert space of SU(2) intertwiners (or, in other words, SU(2)-invariant states in tensor products of irreducible representations). The total boundary area as well as the individual face areas are quantized as half-integers (spins), and the Hilbert spaces for fixed total area form irreducible representations of U(N). We define semi-classical coherent intertwiner states peaked on classical framed polyhedra and transforming consistently under U(N) transformations. And we show how the U(N) character formula for unitary transformations is to be considered as an extension of the Itzykson-Zuber to the quantum level and generates the traces of all polynomial observables over the Hilbert space of intertwiners. We finally apply the same formalism to two dimensions and show that classical (convex) polygons can be described in a similar fashion trading the unitary group for the orthogonal group. We conclude with a discussion of the possible (deformation) dynamics that one can define on the space of polygons or polyhedra. This work is a priori useful in the context of discrete geometry but it should hopefully also be relevant to (loop) quantum gravity in 2+1 and 3+1 dimensions when the quantum geometry is defined in terms of gluing of (quantized) polygons and polyhedra.« less

Towards a Predictive Thermodynamic Model of Oxidation States of Uranium Incorporated in Fe (hydr) oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bagus, Paul S.

The theoretical research in this project has been directed toward the interpretation of core-level spectroscopies for systems relevant to the project. For the initial efforts, the focus of our theoretical simulations has been the interpretation of laboratory and synchrotron X-Ray Photoemission Spectra, XPS. In more recent efforts, an increasing emphasis has been placed on developing transparent understandings of X-Ray Adsorption Spectra, XAS . For the XAS, the principal concern is for the near-edge features, either just below or just above, an ionization limit or edge, which are described as Near-Edge X-Ray Adsorption Fine Structure, NEXAFS. In particular, a priority hasmore » involved the analysis and interpretation of XPS and NEXAFS spectra, especially of Fe and U systems, as measured by our PNNL collaborators. The overall objective of our theoretical studies is to establish connections between features of the spectra and their origin in the electronic structure of the materials. The efforts for the analysis of XPS have been reviewed in a paper by the PI, C. J. Nelin, and E. S. Ilton from PNNL on “The interpretation of XPS spectra: Insights into materials properties”, Surf. Sci. Reports, 68, 273 (2013). Two materials properties of special interest have been the degree of ionicity and the character of the covalent bonding in a range of oxides formed with transition metal, lanthanide, and actinide cations. Since the systems treated have electrons in open shells, it has been necessary to determine the energetics and the character of the angular momentum coupling of the open shell electrons. In particular, we have established methods for the treatment of the “intermediate coupling” which arises when the system is between the limit of Russell-Saunders multiplets, and the limit of j-j coupling where the spin-orbit splittings of single electrons dominate. A recent paper by the PI, and M. J. Sassi, and K. M. Rosso, (both at PNNL) “Intermediate Coupling For Core-Level Excited States: Consequences For X-Ray Absorption Spectroscopy”, J. Elec. Spectros. and Related Phenom., 200, 174 (2015) describes our first application of these methods. As well as applications to problems and materials of direct interest for our PNNL colleagues, we have pursued applications of fundamental theoretical significance for the analysis and interpretation of XPS and XAS spectra. These studies are important for the development of the fields of core-level spectroscopies as well as to advance our capabilities for applications of interest to our PNNL colleagues. An excellent example is our study of the surface core-level shifts, SCLS, for the surface and bulk atoms of an oxide that provides a new approach to understanding how the surface electronic of oxides differs from that in the bulk of the material. This work has the potential to lead to a new key to understanding the reactivity of oxide surfaces. Our theoretical studies use cluster models with finite numbers of atoms to describe the properties of condensed phases and crystals. This approach has allowed us to focus on the local atomistic, chemical interactions. For these clusters, we obtain orbitals and spinors through the solution of the Hartree-Fock, HF, and the fully relativistic Dirac HF equations. These orbitals are used to form configuration mixing wavefunctions which treat the many-body effects responsible for the open shell angular momentum coupling and for the satellites of the core-level spectra. Our efforts have been in two complementary directions. As well as the applications described above, we have placed major emphasis on the enhancement and extension of our theoretical and computational capabilities so that we can treat complex systems with a greater range of many-body effects. Noteworthy accomplishments in terms of method development and enhancement have included: (1) An improvement in our treatment of the large matrices that must be handled when many-body effects are treated. (2) Improvements and extensions of our capabilities for the calculation of the intensities of XPS and XAS transitions. And (3) ongoing development of flexible programs for the visualization of the theoretical spectra so that they can be compared with experiment. Our efforts on applications and methodology for these and related topics will continue under a sub-contract to PNNL.« less

The grasp2K relativistic atomic structure package

NASA Astrophysics Data System (ADS)

Jönsson, P.; He, X.; Froese Fischer, C.; Grant, I. P.

2007-10-01

This paper describes grasp2K, a general-purpose relativistic atomic structure package. It is a modification and extension of the GRASP92 package by [F.A. Parpia, C. Froese Fischer, I.P. Grant, Comput. Phys. Comm. 94 (1996) 249]. For the sake of continuity, two versions are included. Version 1 retains the GRASP92 formats for wave functions and expansion coefficients, but no longer requires preprocessing and more default options have been introduced. Modifications have eliminated some errors, improved the stability, and simplified interactive use. The transition code has been extended to cases where the initial and final states have different orbital sets. Several utility programs have been added. Whereas Version 1 constructs a single interaction matrix for all the J's and parities, Version 2 treats each J and parity as a separate matrix. This block structure results in a reduction of memory use and considerably shorter eigenvectors. Additional tools have been developed for this format. The CPU intensive parts of Version 2 have been parallelized using MPI. The package includes a "make" facility that relies on environment variables. These make it easier to port the application to different platforms. The present version supports the 32-bit Linux and ibmSP environments where the former is compatible with many Unix systems. Descriptions of the features and the program/data flow of the package will be given in some detail in this report. Program summaryProgram title: grasp2K Catalogue identifier: ADZL_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZL_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 213 524 No. of bytes in distributed program, including test data, etc.: 1 328 588 Distribution format: tar.gz Programming language: Fortran and C Computer: Intel Xeon, 3.06 GHz Operating system: Suse LINUX RAM: 500 MB or more Classification: 2.1 Nature of problem: Prediction of atomic spectra—atomic energy levels, oscillator strengths, and radiative decay rates—using a 'fully relativistic' approach. Solution method: Atomic orbitals are assumed to be four-component spinor eigenstates of the angular momentum operator, j=l+s, and the parity operator Π=βπ. Configuration state functions (CSFs) are linear combinations of Slater determinants of atomic orbitals, and are simultaneous eigenfunctions of the atomic electronic angular momentum operator, J, and the atomic parity operator, P. Approximate atomic state functions (ASFs) are linear combinations of CSFs. A variational functional may be constructed by combining expressions for the energies of one or more ASFs. Average energy level (EAL) functionals are weighted sums of energies of all possible ASFs that may be constructed from a set of CSFs; the number of ASFs is then the same as the number of CSFs. Extended optimal level (EOL) functionals are weighted sums of energies of some subset of ASFs. Radial functions may be determined by numerically solving the multiconfiguration Dirac-Hartree-Fock (MCDHF) equations that define an extremum of the variational functional by the self-consistent-field (SCF) method. Lists of CSFs are generated from a set of reference CSFs and rules for deriving other CSFs from these. Expansion coefficients are obtained using sparse-matrix methods for solving the relativistic configuration interaction (CI) problem. Transition properties for pairs of ASFs are computed from matrix elements of multipole operators of the electromagnetic field. Biorthogonal transformation methods are employed so that all matrix elements between CSFs can be evaluated using Racah algebra. Restrictions: The maximum number of radial orbitals is limited to 120 by the packing algorithm used for 32-bit integers. The maximum size of a multiconfiguration (MC) calculation, as measured by the length of the configuration state function (CSF) list, is limited by numerical stability, processing time, or storage which may be either in memory or on disk. Numerical stability is the same as GRASP92 [F.A. Parpia, C. Froese Fischer, I.P. Grant, Comput. Phys. Comm. 94 (1996) 249] with a slight improvement in memory management for Version 2 codes. Sufficient disk space is needed to store angular data. In configuration interaction calculations the matrix may be either in memory or on disk. The tables of coefficients of fractional parentage, as in GRASP92, are limited to subshells with j⩽7/2; occupied subshells with j=9/2 are, therefore, restricted to a maximum of two electrons. Unusual features: The installation process has been simplified so that pre-processing of the raw code needed with GRASP92 can be eliminated. Dynamic memory allocation reduces the number of parameters needed to define fixed array dimensions to nine. The corrections discussed in [C. Froese Fischer, G. Gaigalas, Y. Ralchenko, Comput. Phys. Comm. 175 (2006) 739] have also been implemented. Environment variables are used to facilitate the compilation of the libraries, applications, and tools with different compilers on different platforms. Computationally intensive applications have been parallelized using the message passing interface (MPI). When standard output is redirected, prompts and critical information about the progress of a calculation or convergence are still directed to the screen through the standard error output unit. Running time: CPU time required to execute test cases: 5 min ( n=4 calculation with 2190 CSFs) and 52.7 minutes ( n=5 calculation with 6752 CSFs)

Proceedings of the 8th International Symposium on Foundations of Quantum Mechanics in the Light of New Technology

NASA Astrophysics Data System (ADS)

Ishioka, Sachio; Fujikawa, Kazuo

2006-06-01

Preface -- Committees -- Opening address / H. Fukuyama -- Welcoming address / N. Osakabe -- Special lecture. Albert Einstein: opportunity and perception / C. N. Yang -- Quantum information and entanglement. Quantum optics with single atoms and photons / H. J. Kimble. Quantum information system experiments using a single photon source / Y. Yamamoto. Quantum communication and quantum computation with entangled photons / A. Zeilinger. High-fidelity quantum teleportation and a quantum teleportation network for continuous variables / N. Takei, A. Furusawa. Long lived entangled states / H. Häffner ... [et al.]. Quantum non-locality using tripartite entanglement with non-orthogonal states / J. V. Corbett, D. Home. Quantum entanglement and wedge product / H Heydari. Analysis of the generation of photon pairs in periodically poled lithium niobate / J. Söderholm ... [et al.]. Generation of entangled photons in a semiconductor and violation of Bell's inequality / G. Oohata, R. Shimizu, K. Edamatsu -- Quantum computing. Decoherence of a Josephson junction flux qubit / Y. Nakamura ... [et al.]. Spectroscopic analysis of a candidate two-qubit silicon quantum computer in the microwave regime / J. Gorman, D. G. Hasko, D. A. Williams. Berry phase detection in charge-coupled flux-qubits and the effect of decoherence / H. Nakano ... [et al.]. Locally observable conditions for the successful implementation of entangling multi-qubit quantum gates / H. F. Hofmann, R. Okamoto, S. Takeuchi. State control in flux qubit circuits: manipulating optical selection rules of microwave-assisted transitions in three-level artificial atoms / Y.-X. Liu ... [et al.]. The effect of local structure and non-uniformity on decoherence-free states of charge qubits / T. Tanamoto, S. Fujita. Entanglement-assisted estimation of quantum channels / A. Fujiwara. Superconducting quantum bit with ferromagnetic [symbol]-Junction / T. Yamashita, S. Takahashi, S. Maekawa. Generation of macroscopic Greenberger-Horne-Zeilinger states in Josephson systems / T. Fujii, M. Nishida, N. Hatakenaka -- Quantum-dot systems. Tunable tunnel and exchange couplings in double quantum dots / S. Tarucha, T. Hatano, M. Stopa. Coherent transport through quantum dots / S. Katsumoto ... [et al.]. Electrically pumped single-photon sources towards 1.3 [symbol]m / X. Xu ... [et al.]. Aharonov-Bohm-type effects in antidot arrays and their decoherence / M. Kato ... [et al.]. Nonequilibrium Kondo dot connected to ferromagnetic leads / Y. Utsumi ... [et al.]. Full counting-statistics in a single-electron transistor in the presence of strong quantum fluctuations / Y. Utsumi -- Anomalous Hall effect and Spin-Hall effect. Geometry and the anomalous Hall effect in ferromagnets / N. P. Ong, W.-L. Lee. Control of spin chirality, Berry phase, and anomalous Hall effect / Y. Tokura, Y. Taguchi. Quantum geometry and Hall effect in ferromagnets and semiconductors / N. Nagaosa. Spin-Hall effect in a semiconductor two-dimensional hole gas with strong spin-orbit coupling / J. Wunderlich ... [et al.]. Intrinsic spin Hall effect in semiconductors / S. Murakami -- Spin related phenomena. Theory of spin transfer phenomena in magnetic metals and semiconductors / A. S. Núñez, A. H. MacDonald. Spin filters of semiconductor nanostructures / T. Dietl, G. Grabecki, J. Wróbel. Experimental study on current-driven domain wall motion / T. Ono ... [et al.]. Magnetization reversal of ferromagnetic nano-dot by non local spin injection / Y. Otani, T. Kimura. Theory of current-driven domain wall dynamics / G. Tatara ... [et al.]. Magnetic impurity states and ferromagnetic interaction in diluted magnetic semiconductors / M. Ichimura ... [et al.]. Geometrical effect on spin current in magnetic nano-structures / M. Ichimura, S. Takahashi, S. Maekawa. Ferromagnetism in anatase TiO[symbol] codoped with Co and Nb / T. Hitosugi ... [et al.] -- Superconductivity in nano-systems. Nonlinear quantum effects in nanosuperconductors / C. Carballeira ... [et al.]. Coalescence and rearrangement of vortices in mesoscopic superconductors / A. Kanda ... [et al.]. Superconductivity in topologically nontrivial spaces / M. Hayashi ... [et al.]. DC-SQUID ratchet using atomic point contact / Y. Ootuka, H. Miyazaki, A. Kanda. Superconducting wire network under spatially modulated magnetic field / H. Sano ... [et al.]. Simple and stable control of mechanical break junction for the study of superconducting atomic point contact / H. Miyazaki ... [et al.]. Critical currents in quasiperiodic pinning arrays: one-dimensional chains and Penrose lattices / V. R. Misko, S. Savel'ev, F. Nori. Macroscopic quantum tunneling in high-Tc superconductor Josephson junctions / S. Kawabata -- Novel properties of carbon nanotubes. Carbon nanotubes and unique transport properties: importance of symmetry and channel number / T. Ando. Optical processes in single-walled carbon nanotubes threaded by a magnetic flux / J. Kono ... [et al.]. Non-equilibrium transport through a single-walled carbon nanotube with highly transparent coupling to reservoirs / P. Recher, N. Y. Kim, Y. Yamamoto -- Novel properties of nano-systems. Transport properties in low dimensional artificial lattice of gold nano-particles / S. Saito ... [et al.]. First principles study of dihydride-chain structures on H-terminated Si(100) surface / Y. Suwa ... [et al.]. Electrical property of Ag nanowires fabricated on hydrogen-terminated Si(100) surface / M. Fujimori, S. Heike, T. Hashizume. Effect of environment on ionization of excited atoms embedded in a solid-state cavity / M. Ando ... [et al.]. Development of universal virtual spectroscope for optoelectronics research: first principles software replacing dielectric constant measurements / T. Hamada ... [et al.]. Quantum Nernst effect / H Nakamura, N. Hatano, R. Shirasaki -- Precise measurements. Quantum phenomena visualized using electron waves / A. Tonomura. An optical lattice clock: ultrastable atomic clock with engineered perturbation / H. Katori ... [et al.]. Development of Mach-Zehnder interferometer and "coherent beam steering" technique for cold neutron / K. Taketani ... [et al.]. Surface potential measurement by atomic force microscopy using a quartz resonator / S. Heike, T. Hashizume -- Fundamental Problems in quantum physics. Berry's phases and topological properties in the Born-Oppenheimer approximation / K. Fujikawa. Self-trapping of Bose-Einstein condensates by oscillating interactions / H. Saito, M. Ueda. Spinor solitons in Bose-Einstein condensates - atomic spin transport / J. Ieda. Spin decoherence in a gravitational field / H. Terashima, M. Ueda. Berry's phase of atoms with different sign of the g-factor in a conical rotating magnetic field observed by a time-domain atom interferometer / A. Morinaga ... [et al.] -- List of participants.

Applications of zeta functions and other spectral functions in mathematics and physics: a special issue in honour of Stuart Dowker's 75th birthday Applications of zeta functions and other spectral functions in mathematics and physics: a special issue in honour of Stuart Dowker's 75th birthday

NASA Astrophysics Data System (ADS)

Dowker, Fay; Elizalde, Emilio; Kirsten, Klaus

2012-09-01

John Stuart Dowker was born in Sheffield, Yorkshire, on 18 March 1937. His life, therefore, was very much influenced by the Second World War. This is evident as his father died on active service in 1945, after being called up in 1941. His grandfather also died shortly afterwards, so he did not know either of them very well. Nevertheless, it seems that he picked up a positive attitude towards natural sciences as both were technically minded. His mother later provided, often from borrowed money, all the necessary intellectual food in forms of chemistry sets, slide rules and other things that a boy needed to develop his interests. Stuart scored excellently in the 11-plus exam, which was used to decide the type of school a pupil should attend after primary school. Although Stuart was generally allowed to do what he wanted, his mother insisted that he chose King Edward VII Grammar School (KES), the top school in Sheffield at the time. KES allowed Stuart to fully develop his intellectual abilities, and after the S-level exam he received a prestigious state scholarship which allowed him to study at any university in the country. He picked Nottingham over other possibilities, mainly because of his interest in electronics and because of the relative proximity to his family. In Nottingham, where he stayed from 1955 to 1958, his research concentration turned out to be mostly solid state physics. But with time on his hands, Stuart raided the library and taught himself things like complex analysis and quantum mechanics, with de Broglie's La mécanique ondulatoire [1] as one of his favorites. Remarkably, this book already contains a discussion of quantization on curved configuration spaces, a setting so relevant in Stuart's later career. Stuart wanted to investigate quantum field theory for his doctoral thesis. So he wrote, among others, to Rudolph Peierls in Birmingham, and, after being interviewed by Peierls himself and J G Valatin, he received an offer of a PhD position. He went to Birmingham in 1958, where his supervisor was Leonardo Castillejo, best known from the Castillejo-Dalitz-Dyson-ambiguity see [2]. His thesis involved stripping theory, and on this topic he wrote his first ever publication [3]. Takeaways from that time were that sometimes one simply has to do what one is told, and even more importantly, sometimes one has to get on with a calculation and 'just roll through it'. It was also around that period that Stuart started to learn quantum field theory properly following the developments of Feynman. After his PhD, it was Peierls who helped him to find a position at the University of Pennsylvania in Philadelphia in 1961, which he accepted before he received an offer from CERN. In retrospect, this was probably fortunate as it is where he met his wife, Pwu Yih, to whom he has been married for nearly 50 years. Scientifically he remained somewhat isolated there and spent much of his time learning more about quantum field theory, for example by reading Bogoliubov and Shirkov [4]. His entry point for general relativity was Eddington's The Mathematical Theory of Relativity [5], which together with the works of Julian Schwinger and Bryce de Witt were the most influential ones at that time. A shift of focus to questions in quantum field theory in curved space time took place. After his stay in Philadelphia, in 1963, helped by connections between Abe Klein and Brian Flowers, he went to the University of Manchester, where he remains to this day. This period was only briefly interrupted by a sabbatical in 1978 to 1979 at Austin following an invitation by Bryce de Witt. Looking back, it seems there were two major driving forces or principles that determined much of Stuart's selection of research projects. One of them is the method of images, about which he says: '...it intrigued me that one problem (charge + plane) could be got from another (just charge) by geometrical reasoning plus uniqueness. Thomson's book [6] took this further. Chapter 5 is devoted to the image and inversion methods and I must have read this closely as there are lots of marginal notes...' The second principle can be read off from the following quote: 'After reading Eddington circa 1960 it was clear to me (and others of course) there is a strong analogy (at least) between gravitation and electromagnetism ... (His work has very strongly influenced me.) So I played a game of asking for the gravitational analogues of existing electromagnetic concepts. The basic analogue is between field strength/charge and curvature/spin... [in that] ...spin, in general relativity, plays the passive role that charge plays in electromagnetism in the sense that it is the spin-curvature coupling that knocks a particle off a geodesic.' It is quite amazing how much of Stuart's work can be traced back to these principles. This is briefly explained in the following by describing some of his most important works. His most cited work [7] fits this bill and can be seen as doing what Julian Schwinger did in [8], for a constant electromagnetic field in the gravitational setting. In more detail he noticed Schulman's work on propagators on the three sphere [9], which he extended to Lie groups; see [10, 11]. He then noticed that having exact propagators, work like Schwinger's could be done and de Sitter space was a natural 'curved' candidate. The paper is best known for the mathematical technique introduced, namely for the zeta function method much used since for the computation of singular quantum field theoretic quantities like effective actions and the Casimir energy. The motivation for introducing this scheme goes back to reading an article of I M Gel'fand about some number theory problem involving zeta functions, image sums, propagators etc. How could an object occurring with other objects physicists were using all the time not be useful? It turned out to be very useful, although in this paper the method was only introduced but actually not used! This is probably the reason that his paper did not receive the same recognition as the one by Hawking [12], where zeta function regularization was mentioned in the title and where it was actually applied to examples in the article. Of course, Stuart's and Raymond's paper hit the pulse of the time in that after Stephen Hawking's announcement about Hawking radiation [13], the quantum field theory in curved space-time frenzy began. He had been interested in that subject for a while, the most important influence being de Witt's Les Houches lectures and also Chris Isham, who introduced him to Dennis Sciama's Oxford group, including Philip Candelas and Derek Raine, in 1973. The project about de Sitter space got somewhat delayed by work on path integrals and the ordering problem until Ray Critchley came by looking for a PhD topic. Several more of his best known papers are in the context of quantum field theory in curved spacetime. In the article [14], conformal transformations play a fundamental role. They are used to transform static manifolds to ultra-static ones where a high-temperature expansion of the effective action can be done. The result has since been rediscovered many times for special cases. In the process they also showed results about the conformal transformation of heat kernel coefficients claimed later on by mathematicians. The paper by Kennedy, Critchley and Dowker [15] belongs in the same context. Deutsch and Candelas had shown the occurrence of non-integrable singularities near boundaries of the Casimir energy densities, which made it impossible to obtain global energies by naively integrating local quantities. To resolve that problem, the needed surface counterterms for an arbitrarily shaped smooth boundary in curved space were computed. How does the paper [16] fit into the general scheme? The seed to considering this topic was probably planted when Yakir Aharonov was visiting Birmingham in 1958. In the Aharonov-Bohm effect we have an electromagnetic field with finite extension that impacts particles never entering that region. What is the gravitational analogue for that situation? The analogue concerns the impact a localized curvature has, and the cone is an excellent example to shed light on that question. Related to the method of images, Stuart has done an enormous amount of work on the influence of topology and curvature on quantum field theory. An example is [17], where the vacuum stress-energy tensor for Clifford-Klein forms of the flat or spherical type were computed. Another strand we would like to mention is Stuart's interest in higher spin equations. In [18], Steven Weinberg wrote down a set of higher spin equations that took his fancy. They involved angular momentum theory, which has always pleased Stuart, and the description was an alternative to Roger Penrose's use of two-spinors. Investigating the inconsistencies that arose on coupling to gauge theories, Stuart extended the classic results in [19], from electromagnetism to gravity in accordance with his general philosophy; see, e.g., [20, 21, 22]. Lately, Stuart is best known for his many applications in the context of zeta function regularization and its applications to quantum field theory under external conditions and spectral theory. He can be considered the world expert on particular case calculations with a knowledge of the literature, old and recent, that is not seen very often and which originated in the many hours spent at different (mostly British) libraries. His attitude towards explicit computations is nicely summarized by himself: 'I have always been interested in exact solutions, even if unphysical, so long as they are pretty. They seem to be working mechanisms that fit together, complete in themselves, like a watch.' The following issue in honour of Stuart's 75th birthday contains contributions that touch upon the various topics he has worked on. References [1] de Broglie L 1928 La mécanique ondulatoire (Paris: Gauthier-Villars) [2] Castillejo L, Dalitz R H and Dyson F J 1956 Low's scattering equation for the charged and neutral scalar theories Phys. Rev. 101 453 [3] Dowker J S 1961 Application of the Chew and Low extrapolation procedure to K- + d → Y + N + π absorption reactions Il Nuovo Cimento 10 182 [4] Bogoliubov N N and Shirkov D V 1959 Introduction to the Theory of Quantized Fields (New York: Interscience) [5] Eddington A S 1923 The Mathematical Theory of Relativity (Cambridge: Cambridge University Press) [6] Thomson J J 1909 Elements of Electricity and Magnetism 4th edn (Cambridge: Cambridge University Press) [7] Dowker J S and Critchley R 1976 Effective Lagrangian and energy momentum tensor in de Sitter space Phys. Rev. D 13 3224 [8] Schwinger J 1951 On gauge invariance and vacuum polarization Phys. Rev. 82 664 [9] Schulman L S 1968 A path integral for spin Phys. Rev. 176 1558 [10] Dowker J S 1970 When is the sum over classical paths exact? J. Phys. A: Math. Gen. 3 451 [11] Dowker J S 1971 Quantum mechanics on group space and Huygens' principle Ann. Phys. 62 361 [12] Hawking S W 1977 Zeta function regularization of path integrals in curved space-time Comm. Math. Phys. 55133 [13] Hawking S W 1974 Black hole explosions Nature 248 30 [14] Dowker J S and Kennedy G 1978 Finite temperature and boundary effects in static space-times J. Phys. A: Math. Gen. 11 895 [15] Kennedy G, Critchley R and Dowker J S 1980 Finite temperature field theory with boundaries: stress tensor and surface action renormalization Ann. Phys. 125 346 [16] Dowker J S 1977 Quantum field theory on a cone J. Phys. A: Math. Gen. 10 115 [17] Dowker J S and Banach R 1978 Quantum field theory on Clifford-Klein space-times. The effective Lagrangian and vacuum stress-energy tensor J. Phys. A: Math. Gen. 11 2255 [18] Weinberg S 1964 Feynman rules for any spin Phys. Rev. 133 B1318 [19] Fierz M and Pauli W 1939 On relativistic wave equations for particles of arbitrary spin in an electromagnetic field Proc. Roy. Soc. A 173 221 [20] Dowker J S and Dowker Y P 1966 Particles of arbitrary spin in curved spaces Proc. Phys. Soc. (Lond.) 87 65 [21] Dowker J S and Dowker Y P 1966 Interactions of massless particles of arbitrary spin Proc. Roy. Soc. A 294 175 [22] Dowker J S 1972 Propagators for arbitrary spin in an Einstein universe Ann. Phys. 71 577

Tripolar electric field Structure in guide field magnetic reconnection

NASA Astrophysics Data System (ADS)

Fu, Song; Huang, Shiyong; Zhou, Meng; Ni, Binbin; Deng, Xiaohua

2018-03-01

It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.

[Some comments on ecological field].

PubMed

Wang, D

2000-06-01

Based on the data of plant ecological field studies, this paper reviewed the conception of ecological field, field eigenfunctions, graphs of ecological field and its application of ecological field theory in explaining plant interactions. It is suggested that the basic character of ecological field is material, and based on the current research level, it is not sure whether ecological field is a kind of specific field different from general physical field. The author gave some comments on the formula and estimation of parameters of basic field function-ecological potential model on ecological field. Both models have their own characteristics and advantages in specific conditions. The author emphasized that ecological field had even more meaning of ecological methodology, and applying ecological field theory in describing the types and processes of plant interactions had three characteristics: quantitative, synthetic and intuitionistic. Field graphing might provide a new way to ecological studies, especially applying the ecological field theory might give an appropriate quantitative explanation for the dynamic process of plant populations (coexistence and interference competition).

Electric Field Feature of Moving Magnetic Field

NASA Astrophysics Data System (ADS)

Chen, You Jun

2001-05-01

A new fundamental relationship of electric field with magnetic field has been inferred from the fundamental experimental laws and theories of classical electromagnetics. It can be described as moving magnetic field has or gives electric feature. When a field with magnetic induction of B moves in the velocity of V, it will show electric field character, the electric field intensity E is E = B x V and the direction of E is in the direction of the vector B x V. It is improper to use the time-varying electromagnetics theories as the fundamental theory of the electromagnetics and group the electromagnetic field into static kind and time-varying kind for the static is relative to motional not only time-varying. The relationship of time variation of magnetic field induction or magnetic flux with electric field caused by magnetic field is fellowship not causality. Thus time-varying magnetic field can cause electric field is not a nature principle. Sometime the time variation of magnetic flux is equal to the negative electromotive force or the time variation of magnetic field induction is equal to the negative curl of electric field caused by magnetic field motion, but not always. And not all motion of magnetic field can cause time variation of magnetic field. Therefore Faraday-Lenz`s law can only be used as mathematics tool to calculate the quantity relation of the electricity with the magnetism in some case like the magnetic field moving in uniform medium. Faraday-Lenz`s law is unsuitable to be used in moving uniform magnetic field or there is magnetic shield. Key word: Motional magnetic field, Magnetic induction, Electric field intensity, Velocity, Faraday-Lenz’s law

Oil and gas field code master list 1997

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

The Oil and Gas Field Code Master List 1997 is the sixteenth annual listing of all identified oil and gas fields in the US. It is updated with field information collected through October 1997. The purpose of this publication is to provide unique, standardized codes for identification of domestic fields. Use of these field codes fosters consistency of field identification by government and industry. As a result of their widespread adoption they have in effect become a national standard. The use of field names and codes listed in this publication is required on survey forms and other reports regarding field-specificmore » data collected by EIA. There are 58,366 field records in this year`s FCML, 437 more than last year. The FCML includes: field records for each State and county in which a field resides; field records for each offshore area block in the Gulf of Mexico in which a field resides; field records for each alias field name (definition of alias is listed); fields crossing State boundaries that may be assigned different names by the respective State naming authorities. This report also contains an Invalid Field Record List of 4 records that have been removed from the FCML since last year`s report. These records were found to be either technically incorrect or to represent field names which were never recognized by State naming authorities.« less

How fields vary.

PubMed

Krause, Monika

2018-03-01

Field theorists have long insisted that research needs to pay attention to the particular properties of each field studied. But while much field-theoretical research is comparative, either explicitly or implicitly, scholars have only begun to develop the language for describing the dimensions along which fields can be similar to and different from each other. In this context, this paper articulates an agenda for the analysis of variable properties of fields. It discusses variation in the degree but also in the kind of field autonomy. It discusses different dimensions of variation in field structure: fields can be more or less contested, and more or less hierarchical. The structure of symbolic oppositions in a field may take different forms. Lastly, it analyses the dimensions of variation highlighted by research on fields on the sub- and transnational scale. Post-national analysis allows us to ask how fields relate to fields of the same kind on different scales, and how fields relate to fields on the same scale in other national contexts. It allows us to ask about the role resources from other scales play in structuring symbolic oppositions within fields. A more fine-tuned vocabulary for field variation can help us better describe particular fields and it is a precondition for generating hypotheses about the conditions under which we can expect to observe fields with specified characteristics. © London School of Economics and Political Science 2017.

Oil and Gas field code master list 1995

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

This is the fourteenth annual edition of the Energy Information Administration`s (EIA) Oil and Gas Field Code Master List. It reflects data collected through October 1995 and provides standardized field name spellings and codes for all identified oil and/or gas fields in the US. The Field Code Index, a listing of all field names and the States in which they occur, ordered by field code, has been removed from this year`s publications to reduce printing and postage costs. Complete copies (including the Field Code Index) will be available on the EIA CD-ROM and the EIA World-Wide Web Site. Future editionsmore » of the complete Master List will be available on CD-ROM and other electronic media. There are 57,400 field records in this year`s Oil and Gas Field Code Master List. As it is maintained by EIA, the Master List includes the following: field records for each State and county in which a field resides; field records for each offshore area block in the Gulf of Mexico in which a field resides; field records for each alias field name (see definition of alias below); and fields crossing State boundaries that may be assigned different names by the respective State naming authorities. Taking into consideration the double-counting of fields under such circumstances, EIA identifies 46,312 distinct fields in the US as of October 1995. This count includes fields that no longer produce oil or gas, and 383 fields used in whole or in part for oil or gas Storage. 11 figs., 6 tabs.« less

Sci-Sat AM: Radiation Dosimetry and Practical Therapy Solutions - 12: Suitability of plan class specific reference fields for estimating dosimeter correction factors for small clinical CyberKnife fields

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vandervoort, Eric; Christiansen, Eric; Belec, Jaso

Purpose: The purpose of this work is to investigate the utility of plan class specific reference (PCSR) fields for predicting dosimeter response within isocentric and non-isocentric composite clinical fields using the smallest fields employed by the CyberKnife radiosurgery system. Methods: Monte Carlo dosimeter response correction factors (CFs) were calculated for a plastic scintillator and microchamber dosimeter in 21 clinical fields and 9 candidate plan-class PCSR fields which employ the 5, 7.5 and 10 mm diameter collimators. Measurements were performed in 5 PCSR fields to confirm the predicted relative response of detectors in the same field. Results: Ratios of corrected measuredmore » dose in the PCSR fields agree to within 1% of unity. Calculated CFs for isocentric fields agree within 1.5% of those for PCSR fields. Large and variable microchamber CFs are required for non-isocentric fields, with differences as high as 5% between different clinical fields in the same plan class and 4% within the same field depending on the point of measurement. Non-isocentric PCSR fields constructed to have relatively homogenous dose over a region larger than the detector have very different ion chamber CFs from clinical fields. The plastic scintillator detector has much more consistent response within each plan class but still require 3–4% corrections in some fields. Conclusions: While the PCSR field concept is useful for small isocentric fields, this approach may not be appropriate for non-isocentric clinical fields which exhibit large and variable ion chamber CFs which differ significantly from CFs for homogenous field PCSRs.« less

Book Review:

NASA Astrophysics Data System (ADS)

Wainwright, John

2007-04-01

The present volume is an introduction to general relativity and cosmology, at a level suitable for beginning graduate students or advanced undergraduates. The book consists of two main parts, the first entitled `Elements of differential geometry', and the second `The theory of gravitation'. Chapters 2-7, part I, introduce the basic ideas of differential geometry in a general setting, and are based on previously unpublished notes by one of the authors. On the one hand, the treatment is modern in that it uses a `top-down' approach, i.e. starting with general differentiable manifolds, and deferring the introduction of a metric tensor until after the notions of affine connection and curvature have been introduced. On the other hand, the treatment is classical in that it relies heavily, though not exclusively, on index notation. The general material, chapters 1-7, is then followed by four more specialized chapters dealing with matters of specific interest for general relativity. Topics include symmetry groups acting on Riemannian manifolds, with spherically symmetric spacetimes and spatially homogeneous spacetimes as examples, the efficient calculation of curvature, and the Petrov classification of the Weyl curvature tensor using spinors. Part II deals with general relativity and cosmology. The basic assumptions of the theory and its application to spherically symmetric gravitational fields are discussed in two chapters, and there is some historical material and motivation for the basic assumptions at the beginning of the book. The final chapter contains a detailed discussion of the Kerr solution. But the main emphasis in part II is on relativistic cosmology, in particular the analysis of cosmological models more general than the familiar Friedmann-Lemaitre (FL) models. The material on cosmology begins with a discussion of relativistic hydrodynamics and thermodynamics. The kinematical quantities (rate of expansion, shear, etc, of a timelike congruence) are introduced and their evolution equations are derived. There follows a description of the fluid model of the Universe and optical observations in such a model, within the framework of a general spacetime geometry. The discussion is subsequently specialized to the Robertson-Walker geometry and the FL models. The rest of part II, two lengthy chapters, deals with two classes of solutions of Einstein's field equations that represent spatially inhomogeneous cosmological models, and that contain the FL models as a special case. The first is the family of Lemaitre-Tolman solutions, whose discovery dates back to the 1930s. They are spherically symmetric solutions of Einstein's field equations with pressure-free matter and a cosmological constant as the matter-energy content. The second class is the family of Szekeres solutions, which can be thought of as generalizations of the Lemaitre-Tolman solutions without any symmetries. Parts of these two chapters are based on Krasinski's book on inhomogeneous cosmologies [4], with the difference that the present work does not attempt to be comprehensive, but instead provides clear derivations of the most important results. A potential reader may ask how this book differs from other texts on general relativity. It is unique in a number of respects. First is the authors' emphasis on spatially inhomogeneous cosmological models, i.e. models that do not satisfy the cosmological principle. The authors appear to have reservations about the almost universal preference in the cosmological community for working within the framework of the FL models, combined with the inflationary scenario in the very early universe (see in particular, pages 235-6, and sections 17.8-17.10), and these reservations motivate the above emphasis. They remind the reader that the FL models are based on the cosmological principle, which has a philosophical rather than a physical status, since it cannot be directly tested by observation. In other words, observations alone do not uniquely select the FL models (see also [3], section 5.5, in this regard). Moreover the interpretation of cosmological observations depends on the choice of the underlying spacetime geometry. For example, there is ambiguity in inferring the spatial distribution of matter from redshift measurements. The authors discuss in some detail the work of Kurki-Suonio and Liang [5] to illustrate this point. They also refer to Celerier [1] who shows that the high redshift type Ia supernovae observations are compatible with a Lemaitre-Tolman model with zero cosmological constant, i.e. these observations do not imply that the universe is accelerating if one considers models more general than the FL models, in contrast to the usual interpretation. The authors also give a critique of the cosmological inflation scenario, arguing that the problems that it aims to solve (the so-called horizon problem and the flatness problem) are a consequence of the very special geometry of the FL models. In particular, the flatness problem loses its urgency when one broadens the class of cosmological models, since the condition for flatness depends on spatial position. They also discuss in detail an analysis due to Celerier and Schneider [2] showing how the horizon problem can be resolved using a delayed big-bang singularity in a Lemaitre-Tolman cosmology (section 18.17). We comment on two notable omissions as regards cosmology. First, the authors only refer in passing to the notion of the density parameter, which plays an important role in the analysis of the FL models, and which can also be introduced in more general models. Second, there is no discussion of perturbations of the FL models, although two related concepts, the density contrast and the curvature contrast, are analysed in the Lemaitre-Tolman models (section 18.19). A second unusual feature is that there is a considerable emphasis on exact solutions, their derivation and physical interpretation. Derivations that are given in detail are for the spatially homogeneous solution of Bianchi type I with pressure-free matter, the Lemaitre-Tolman solutions, the Szekeres solutions and the Kerr solution (the original derivation using the Kerr-Schild metric, and Carter's derivation using separability of the Klein-Gordon equation). Readers may wish to compare the above-mentioned derivation of the Bianchi type I solutions, which uses metric components and coordinates, with the derivation given in [3] (see section 5.3), using the orthonormal frame formalism. In summary, this book is an interesting and informative introduction to general relativity and cosmology. The unconventional choice of topics and emphasis may, however, lead some readers to conclude that it may be more suitable as a reference work than as the text for a course. References [1] Celerier M N 2000 Do we really see a cosmological constant in the supernovae data? Astron. Astrophys. 353 63 [2] Celerier M N and Schneider J 1998 A solution to the horizon problem: a delayed big bang singularity Phys. Lett. A 249 37 [3] Ellis G F R and van Elst H 1999 Cosmological models Theoretical and Observational Cosmology ed M Lachieze-Rey (Dordrecht: Kluwer) [4] Krasinski A 1997 Inhomogeneous Cosmological Models (Cambridge: Cambridge University Press) [5] Kurki-Suonio H and Liang E 1992 Relation of redshift surveys to matter distribution in spherically symmetric dust Universes Astrophys. J. 390 5

Levitation forces of a bulk YBCO superconductor in gradient varying magnetic fields

NASA Astrophysics Data System (ADS)

Jiang, J.; Gong, Y. M.; Wang, G.; Zhou, D. J.; Zhao, L. F.; Zhang, Y.; Zhao, Y.

2015-09-01

The levitation forces of a bulk YBCO superconductor in gradient varying high and low magnetic fields generated from a superconducting magnet were investigated. The magnetic field intensity of the superconducting magnet was measured when the exciting current was 90 A. The magnetic field gradient and magnetic force field were both calculated. The YBCO bulk was cooled by liquid nitrogen in field-cooling (FC) and zero-field-cooling (ZFC) condition. The results showed that the levitation forces increased with increasing the magnetic field intensity. Moreover, the levitation forces were more dependent on magnetic field gradient and magnetic force field than magnetic field intensity.

Automated objective characterization of visual field defects in 3D

NASA Technical Reports Server (NTRS)

Fink, Wolfgang (Inventor)

2006-01-01

A method and apparatus for electronically performing a visual field test for a patient. A visual field test pattern is displayed to the patient on an electronic display device and the patient's responses to the visual field test pattern are recorded. A visual field representation is generated from the patient's responses. The visual field representation is then used as an input into a variety of automated diagnostic processes. In one process, the visual field representation is used to generate a statistical description of the rapidity of change of a patient's visual field at the boundary of a visual field defect. In another process, the area of a visual field defect is calculated using the visual field representation. In another process, the visual field representation is used to generate a statistical description of the volume of a patient's visual field defect.

Bifunctional metamaterials with simultaneous and independent manipulation of thermal and electric fields.

PubMed

Lan, Chuwen; Bi, Ke; Fu, Xiaojian; Li, Bo; Zhou, Ji

2016-10-03

Metamaterials offer a powerful way to manipulate a variety of physical fields ranging from wave fields (electromagnetic field, acoustic field, elastic wave, etc.), static fields (static magnetic field, static electric field) to diffusive fields (thermal field, diffusive mass). However, the relevant reports and studies are usually limited to a single physical field or functionality. In this study, we proposed and experimentally demonstrated a bifunctional metamaterial which could manipulate thermal and electric fields simultaneously and independently. Specifically, a composite with independently controllable thermal and electric conductivity was introduced, on the basis of which a bifunctional device capable of shielding thermal flux and concentrating electric current simultaneously was designed, fabricated and characterized. This work provides an encouraging example of metamaterials transcending their natural limitations, which offers a promising future in building a broad platform for the manipulation of multi-physics fields.

Oil and Gas Field Code Master List 1990

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This is the ninth annual edition of the Energy Information Administration's (EIA) Oil and Gas Field Code Master List. It reflects data collected through October 1990 and provides standardized field name spellings and codes for all identified oil and/or gas fields in the United States. There are 54,963 field records in this year's Oil and Gas Field Code Master List (FCML). This amounts to 467 more than in last year's report. As it is maintained by EIA, the Master List includes: Field records for each state and county in which a field resides; field records for each offshore area blockmore » in the Gulf of Mexico in which a field resides;field records for each alias field name; fields crossing state boundaries that may be assigned different names by the respective state naming authorities.« less

Constrained optimization for position calibration of an NMR field camera.

PubMed

Chang, Paul; Nassirpour, Sahar; Eschelbach, Martin; Scheffler, Klaus; Henning, Anke

2018-07-01

Knowledge of the positions of field probes in an NMR field camera is necessary for monitoring the B 0 field. The typical method of estimating these positions is by switching the gradients with known strengths and calculating the positions using the phases of the FIDs. We investigated improving the accuracy of estimating the probe positions and analyzed the effect of inaccurate estimations on field monitoring. The field probe positions were estimated by 1) assuming ideal gradient fields, 2) using measured gradient fields (including nonlinearities), and 3) using measured gradient fields with relative position constraints. The fields measured with the NMR field camera were compared to fields acquired using a dual-echo gradient recalled echo B 0 mapping sequence. Comparisons were done for shim fields from second- to fourth-order shim terms. The position estimation was the most accurate when relative position constraints were used in conjunction with measured (nonlinear) gradient fields. The effect of more accurate position estimates was seen when compared to fields measured using a B 0 mapping sequence (up to 10%-15% more accurate for some shim fields). The models acquired from the field camera are sensitive to noise due to the low number of spatial sample points. Position estimation of field probes in an NMR camera can be improved using relative position constraints and nonlinear gradient fields. Magn Reson Med 80:380-390, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

High magnetic field ohmically decoupled non-contact technology

DOEpatents

Wilgen, John [Oak Ridge, TN; Kisner, Roger [Knoxville, TN; Ludtka, Gerard [Oak Ridge, TN; Ludtka, Gail [Oak Ridge, TN; Jaramillo, Roger [Knoxville, TN

2009-05-19

Methods and apparatus are described for high magnetic field ohmically decoupled non-contact treatment of conductive materials in a high magnetic field. A method includes applying a high magnetic field to at least a portion of a conductive material; and applying an inductive magnetic field to at least a fraction of the conductive material to induce a surface current within the fraction of the conductive material, the surface current generating a substantially bi-directional force that defines a vibration. The high magnetic field and the inductive magnetic field are substantially confocal, the fraction of the conductive material is located within the portion of the conductive material and ohmic heating from the surface current is ohmically decoupled from the vibration. An apparatus includes a high magnetic field coil defining an applied high magnetic field; an inductive magnetic field coil coupled to the high magnetic field coil, the inductive magnetic field coil defining an applied inductive magnetic field; and a processing zone located within both the applied high magnetic field and the applied inductive magnetic field. The high magnetic field and the inductive magnetic field are substantially confocal, and ohmic heating of a conductive material located in the processing zone is ohmically decoupled from a vibration of the conductive material.

Saturation of the Electric Field Transmitted to the Magnetosphere

NASA Technical Reports Server (NTRS)

Lyatsky, Wladislaw; Khazanov, George V.; Slavin, James A.

2010-01-01

We reexamined the processes leading to saturation of the electric field, transmitted into the Earth's ionosphere from the solar wind, incorporating features of the coupled system previously ignored. We took into account that the electric field is transmitted into the ionosphere through a region of open field lines, and that the ionospheric conductivity in the polar cap and auroral zone may be different. Penetration of the electric field into the magnetosphere is linked with the generation of the Alfven wave, going out from the ionosphere into the solar wind and being coupled with the field-aligned currents at the boundary of the open field limes. The electric field of the outgoing Alfven wave reduces the original electric field and provides the saturation effect in the electric field and currents during strong geomagnetic disturbances, associated with increasing ionospheric conductivity. The electric field and field-aligned currents of this Alfven wave are dependent on the ionospheric and solar wind parameters and may significantly affect the electric field and field-aligned currents, generated in the polar ionosphere. Estimating the magnitude of the saturation effect in the electric field and field-aligned currents allows us to improve the correlation between solar wind parameters and resulting disturbances in the Earth's magnetosphere.

Pulsed magnetic field generation suited for low-field unilateral nuclear magnetic resonance systems

NASA Astrophysics Data System (ADS)

Gaunkar, Neelam Prabhu; Selvaraj, Jayaprakash; Theh, Wei-Shen; Weber, Robert; Mina, Mani

2018-05-01

Pulsed magnetic fields can be used to provide instantaneous localized magnetic field variations. In presence of static fields, pulsed field variations are often used to apply torques and in-effect to measure behavior of magnetic moments in different states. In this work, the design and experimental performance of a pulsed magnetic field generator suited for low static field nuclear magnetic resonance (NMR) applications is presented. One of the challenges of low bias field NMR measurements is low signal to noise ratio due to the comparable nature of the bias field and the pulsed field. Therefore, a circuit is designed to apply pulsed currents through an inductive load, leading to generation of pulsed magnetic fields which can temporarily overpower the effect of the bias field on magnetic moments. The designed circuit will be tuned to operate at the precession frequency of 1H (protons) placed in a bias field produced by permanent magnets. The designed circuit parameters may be tuned to operate under different bias conditions. Therefore, low field NMR measurements can be performed for different bias fields. Circuit simulations were used to determine design parameters, corresponding experimental measurements will be presented in this work.

Acoustic source localization in mixed field using spherical microphone arrays

NASA Astrophysics Data System (ADS)

Huang, Qinghua; Wang, Tong

2014-12-01

Spherical microphone arrays have been used for source localization in three-dimensional space recently. In this paper, a two-stage algorithm is developed to localize mixed far-field and near-field acoustic sources in free-field environment. In the first stage, an array signal model is constructed in the spherical harmonics domain. The recurrent relation of spherical harmonics is independent of far-field and near-field mode strengths. Therefore, it is used to develop spherical estimating signal parameter via rotational invariance technique (ESPRIT)-like approach to estimate directions of arrival (DOAs) for both far-field and near-field sources. In the second stage, based on the estimated DOAs, simple one-dimensional MUSIC spectrum is exploited to distinguish far-field and near-field sources and estimate the ranges of near-field sources. The proposed algorithm can avoid multidimensional search and parameter pairing. Simulation results demonstrate the good performance for localizing far-field sources, or near-field ones, or mixed field sources.

Light field imaging and application analysis in THz

NASA Astrophysics Data System (ADS)

Zhang, Hongfei; Su, Bo; He, Jingsuo; Zhang, Cong; Wu, Yaxiong; Zhang, Shengbo; Zhang, Cunlin

2018-01-01

The light field includes the direction information and location information. Light field imaging can capture the whole light field by single exposure. The four-dimensional light field function model represented by two-plane parameter, which is proposed by Levoy, is adopted in the light field. Acquisition of light field is based on the microlens array, camera array and the mask. We calculate the dates of light-field to synthetize light field image. The processing techniques of light field data include technology of refocusing rendering, technology of synthetic aperture and technology of microscopic imaging. Introducing the technology of light field imaging into THz, the efficiency of 3D imaging is higher than that of conventional THz 3D imaging technology. The advantages compared with visible light field imaging include large depth of field, wide dynamic range and true three-dimensional. It has broad application prospects.

Optical field enhancement of nanometer-sized gaps at near-infrared frequencies.

PubMed

Ahn, Jae Sung; Kang, Taehee; Singh, Dilip K; Bahk, Young-Mi; Lee, Hyunhwa; Choi, Soo Bong; Kim, Dai-Sik

2015-02-23

We report near-field and far-field measurements of transmission through nanometer-sized gaps at near-infrared frequencies with varying the gap size from 1 nm to 10 nm. In the far-field measurements, we excluded direct transmission on the metal film surface via interferometric method. Kirchhoff integral formalism was used to relate the far-field intensity to the electric field at the nanogaps. In near-field measurements, field enhancement factors of the nanogaps were quantified by measuring transmission of the nanogaps using near-field scanning optical microscopy. All the measurements produce similar field enhancements of about ten, which we put in the context of comparing with the giant field enhancements in the terahertz regime.

Electromagnetic fields and their impacts

NASA Astrophysics Data System (ADS)

Prša, M. A.; Kasaš-Lažetić, K. K.

2018-01-01

The main goal of this paper is to briefly recall some different electromagnetic field definitions, some macroscopic sources of electromagnetic fields, electromagnetic fields classification regarding time dependences, and the ways of field determination in concrete cases. After that, all the mechanisms of interaction between electromagnetic field and substance, on atomic level, are described in details. Interaction between substance and electric field is investigated separately from the substance and magnetic field interaction. It is demonstrated that, in all cases of the unique electromagnetic field, total interaction can be treated as a superposition of two separated interactions. Finally, the main electromagnetic fields surrounding us is cited and discussed.

CTEPP STANDARD OPERATING PROCEDURE FOR CONDUCTING INTERNAL FIELD AUDITS AND QUALITY CONTROL (SOP-2.25)

EPA Science Inventory

This SOP describes the method for conducting internal field audits and quality control procedures. Internal field audits will be conducted to ensure the collection of high quality data. Internal field audits will be conducted by Field Auditors (the Field QA Officer and the Field...

Machine Learning Classification of Heterogeneous Fields to Estimate Physical Responses

NASA Astrophysics Data System (ADS)

McKenna, S. A.; Akhriev, A.; Alzate, C.; Zhuk, S.

2017-12-01

The promise of machine learning to enhance physics-based simulation is examined here using the transient pressure response to a pumping well in a heterogeneous aquifer. 10,000 random fields of log10 hydraulic conductivity (K) are created and conditioned on a single K measurement at the pumping well. Each K-field is used as input to a forward simulation of drawdown (pressure decline). The differential equations governing groundwater flow to the well serve as a non-linear transform of the input K-field to an output drawdown field. The results are stored and the data set is split into training and testing sets for classification. A Euclidean distance measure between any two fields is calculated and the resulting distances between all pairs of fields define a similarity matrix. Similarity matrices are calculated for both input K-fields and the resulting drawdown fields at the end of the simulation. The similarity matrices are then used as input to spectral clustering to determine groupings of similar input and output fields. Additionally, the similarity matrix is used as input to multi-dimensional scaling to visualize the clustering of fields in lower dimensional spaces. We examine the ability to cluster both input K-fields and output drawdown fields separately with the goal of identifying K-fields that create similar drawdowns and, conversely, given a set of simulated drawdown fields, identify meaningful clusters of input K-fields. Feature extraction based on statistical parametric mapping provides insight into what features of the fields drive the classification results. The final goal is to successfully classify input K-fields into the correct output class, and also, given an output drawdown field, be able to infer the correct class of input field that created it.

Comparison of cardiac and 60 Hz magnetically induced electric fields measured in anesthetized rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, D.L.; Creim, J.A.

1997-06-01

Extremely low frequency magnetic fields interact with an animal by inducing internal electric fields, which are in addition to the normal endogenous fields present in living animals. Male rats weighing about 560 g each were anesthetized with ketamine and xylazine. Small incisions were made in the ventral body wall at the chest and upper abdomen to position a miniature probe for measuring internal electric fields. The calibration constant for the probe size was 5.7 mm, with a flat response from at least 12 Hz to 20 kHz. A cardiac signal, similar to the normal electrocardiogram with a heart rate ofmore » about 250 bpm, was readily obtained at the chest. Upon analysis of its spectrum, the cardiac field detected by the probe had a broad maximum at 32--95 Hz. When the rates were exposed to a 1 mT, 60 Hz magnetic field, a spike appeared in the spectrum at 60 Hz. The peak-to-peak magnitudes of electric fields associated with normal heart function were comparable to fields induced by a 1 mT magnetic field at 60 Hz for those positions measured on the body surface. Within the body, or in different directions relative to the applied field, the induced fields were reduced. The cardiac field increased near the heart, becoming much larger than the induced field. Thus, the cardiac electric field, together with the other endogenous fields, combine with induced electric fields and help to provide reference levels for the induced-field dosimetry of ELF magnetic field exposures of living animals.« less

Sensitivity-based virtual fields for the non-linear virtual fields method

NASA Astrophysics Data System (ADS)

Marek, Aleksander; Davis, Frances M.; Pierron, Fabrice

2017-09-01

The virtual fields method is an approach to inversely identify material parameters using full-field deformation data. In this manuscript, a new set of automatically-defined virtual fields for non-linear constitutive models has been proposed. These new sensitivity-based virtual fields reduce the influence of noise on the parameter identification. The sensitivity-based virtual fields were applied to a numerical example involving small strain plasticity; however, the general formulation derived for these virtual fields is applicable to any non-linear constitutive model. To quantify the improvement offered by these new virtual fields, they were compared with stiffness-based and manually defined virtual fields. The proposed sensitivity-based virtual fields were consistently able to identify plastic model parameters and outperform the stiffness-based and manually defined virtual fields when the data was corrupted by noise.

Effects of a parallel electric field and the geomagnetic field in the topside ionosphere on auroral and photoelectron energy distributions

NASA Technical Reports Server (NTRS)

Min, Q.-L.; Lummerzheim, D.; Rees, M. H.; Stamnes, K.

1993-01-01

The consequences of electric field acceleration and an inhomogeneous magnetic field on auroral electron energy distributions in the topside ionosphere are investigated. The one-dimensional, steady state electron transport equation includes elastic and inelastic collisions, an inhomogeneous magnetic field, and a field-aligned electric field. The case of a self-consistent polarization electric field is considered first. The self-consistent field is derived by solving the continuity equation for all ions of importance, including diffusion of O(+) and H(+), and the electron and ion energy equations to derive the electron and ion temperatures. The system of coupled electron transport, continuity, and energy equations is solved numerically. Recognizing observations of parallel electric fields of larger magnitude than the baseline case of the polarization field, the effect of two model fields on the electron distribution function is investigated. In one case the field is increased from the polarization field magnitude at 300 km to a maximum at the upper boundary of 800 km, and in another case a uniform field is added to the polarization field. Substantial perturbations of the low energy portion of the electron flux are produced: an upward directed electric field accelerates the downward directed flux of low-energy secondary electrons and decelerates the upward directed component. Above about 400 km the inhomogeneous magnetic field produces anisotropies in the angular distribution of the electron flux. The effects of the perturbed energy distributions on auroral spectral emission features are noted.

Effects of a Parallel Electric Field and the Geomagnetic Field in the Topside Ionosphere on Auroral and Photoelectron Energy Distributions

NASA Technical Reports Server (NTRS)

Min, Q.-L.; Lummerzheim, D.; Rees, M. H.; Stamnes, K.

1993-01-01

The consequences of electric field acceleration and an inhomogencous magnetic field on auroral electron energy distributions in the topside ionosphere are investigated. The one- dimensional, steady state electron transport equation includes elastic and inelastic collisions, an inhomogencous magnetic field, and a field-aligned electric field. The case of a self-consistent polarization electric field is considered first. The self-consistent field is derived by solving the continuity equation for all ions of importance, including diffusion of 0(+) and H(+), and the electron and ion energy equations to derive the electron and ion temperatures. The system of coupled electron transport, continuity, and energy equations is solved numerically. Recognizing observations of parallel electric fields of larger magnitude than the baseline case of the polarization field, the effect of two model fields on the electron distribution function in investigated. In one case the field is increased from the polarization field magnitude at 300 km to a maximum at the upper boundary of 800 km, and in another case a uniform field is added to the polarization field. Substantial perturbations of the low energy portion of the electron flux are produced: an upward directed electric field accelerates the downward directed flux of low-energy secondary electrons and decelerates the upward directed component. Above about 400 km the inhomogencous magnetic field produces anisotropies in the angular distribution of the electron flux. The effects of the perturbed energy distributions on auroral spectral emission features are noted.

Permanent magnetic field, direct electric field, and infrared to reduce blood glucose level and hepatic function in mus musculus with diabetic mellitus

NASA Astrophysics Data System (ADS)

Suhariningsih; Basuki Notobroto, Hari; Winarni, Dwi; Achmad Hussein, Saikhu; Anggono Prijo, Tri

2017-05-01

Blood contains several electrolytes with positive (cation) and negative (anion) ion load. Both electrolytes deliver impulse synergistically adjusting body needs. Those electrolytes give specific effect to external disturbance such as electric, magnetic, even infrared field. A study has been conducted to reduce blood glucose level and liver function, in type 2 Diabetes Mellitus patients, using Biophysics concept which uses combination therapy of permanent magnetic field, electric field, and infrared. This study used 48 healthy mice (mus musculus), male, age 3-4 weeks, with approximately 25-30 g in weight. Mice was fed with lard as high fat diet orally, before Streptozotocin (STZ) induction become diabetic mice. Therapy was conducted by putting mice in a chamber that emits the combination of permanent magnetic field, electric field, and infrared, every day for 1 hour for 28 days. There were 4 combinations of therapy/treatment, namely: (1) permanent magnetic field, direct electric field, and infrared; (2) permanent magnetic field, direct electric field, without infrared; (3) permanent magnetic field, alternating electric field, and infrared; and (4) permanent magnetic field, alternating electric field, without infrared. The results of therapy show that every combination is able to reduce blood glucose level, AST, and ALT. However, the best result is by using combination of permanent magnetic field, direct electric field, and infrared.

15 CFR Supplement No. 1 to Part 718 - Confidential Business Information Declared or Reported *

Code of Federal Regulations, 2010 CFR

2010-01-01

... information Schedule 1 Forms: Certification Form NONE. Form 1-1 NONE. Form 1-2 All fields. Form 1-2A All fields. Form 1-2B All fields. Form 1-3 All fields. Form 1-4 All fields. Schedule 2 Forms: Certification... All fields. Form 2-3C All fields. Form 2-4 All fields. Schedule 3 Forms: Certification Form NONE. Form...

Fractal vector optical fields.

PubMed

Pan, Yue; Gao, Xu-Zhen; Cai, Meng-Qiang; Zhang, Guan-Lin; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian

2016-07-15

We introduce the concept of a fractal, which provides an alternative approach for flexibly engineering the optical fields and their focal fields. We propose, design, and create a new family of optical fields-fractal vector optical fields, which build a bridge between the fractal and vector optical fields. The fractal vector optical fields have polarization states exhibiting fractal geometry, and may also involve the phase and/or amplitude simultaneously. The results reveal that the focal fields exhibit self-similarity, and the hierarchy of the fractal has the "weeding" role. The fractal can be used to engineer the focal field.

Cloaking magnetic field and generating electric field with topological insulator and superconductor bi-layer sphere

NASA Astrophysics Data System (ADS)

Xu, Jin

2017-12-01

When an electric field is applied on a topological insulator, not only the electric field is generated, but also the magnetic field is generated, vice versa. I designed topological insulator and superconductor bi-layer magnetic cloak, derived the electric field and magnetic field inside and outside the topological insulator and superconductor sphere. Simulation and calculation results show that the applied magnetic field is screened by the topological insulator and superconductor bi-layer, and the electric field is generated in the cloaked region.

Electrostatic Field Invisibility Cloak

NASA Astrophysics Data System (ADS)

Lan, Chuwen; Yang, Yuping; Geng, Zhaoxin; Li, Bo; Zhou, Ji

2015-11-01

The invisibility cloak has been drawing much attention due to its new concept for manipulating many physical fields, from oscillating wave fields (electromagnetic, acoustic and elastic) to static magnetic fields, dc electric fields, and diffusive fields. Here, an electrostatic field invisibility cloak has been theoretically investigated and experimentally demonstrated to perfectly hide two dimensional objects without disturbing their external electrostatic fields. The desired cloaking effect has been achieved via both cancelling technology and transformation optics (TO). This study demonstrates a novel way for manipulating electrostatic fields, which shows promise for a wide range of potential applications.

Chromatic discrimination: differential contributions from two adapting fields

PubMed Central

Cao, Dingcai; Lu, Yolanda H.

2012-01-01

To test whether a retinal or cortical mechanism sums contributions from two adapting fields to chromatic discrimination, L/M discrimination was measured with a test annulus surrounded by an inner circular field and an outer rectangular field. A retinal summation mechanism predicted that the discrimination pattern would not change with a change in the fixation location. Therefore, the fixation was set either in the inner or the outer field in two experiments. When one of the adapting fields was “red” and the other was “green,” the adapting field where the observer fixated always had a stronger influence on chromatic discrimination. However, when one adapting field was “white” and the other was red or green, the white field always weighted more heavily than the other adapting field in determining discrimination thresholds, whether the white field or the fixation was in the inner or outer adapting field. These results suggest that a cortical mechanism determines the relative contributions from different adapting fields. PMID:22330364

Chromatic discrimination: differential contributions from two adapting fields.

PubMed

Cao, Dingcai; Lu, Yolanda H

2012-02-01

To test whether a retinal or cortical mechanism sums contributions from two adapting fields to chromatic discrimination, L/M discrimination was measured with a test annulus surrounded by an inner circular field and an outer rectangular field. A retinal summation mechanism predicted that the discrimination pattern would not change with a change in the fixation location. Therefore, the fixation was set either in the inner or the outer field in two experiments. When one of the adapting fields was "red" and the other was "green," the adapting field where the observer fixated always had a stronger influence on chromatic discrimination. However, when one adapting field was "white" and the other was red or green, the white field always weighted more heavily than the other adapting field in determining discrimination thresholds, whether the white field or the fixation was in the inner or outer adapting field. These results suggest that a cortical mechanism determines the relative contributions from different adapting fields. © 2012 Optical Society of America

Impact of toroidal and poloidal mode spectra on the control of non-axisymmetric fields in tokamaks

NASA Astrophysics Data System (ADS)

Lanctot, Matthew J.

2016-10-01

In several tokamaks, non-axisymmetric magnetic field studies show applied n=2 fields can lead to disruptive n=1 locked modes, suggesting nonlinear mode coupling. A multimode plasma response to n=2 fields can be observed in H-mode plasmas, in contrast to the single-mode response found in Ohmic plasmas. These effects highlight a role for n >1 error field correction in disruption avoidance, and identify additional degrees of freedom for 3D field optimization at high plasma pressure. In COMPASS, EAST, and DIII-D Ohmic plasmas, n=2 magnetic reconnection thresholds in otherwise stable discharges are readily accessed at edge safety factors q 3 and low density. Similar to previous studies, the thresholds are correlated with the ``overlap'' field for the dominant linear ideal MHD plasma mode calculated with the IPEC code. The overlap field measures the plasma-mediated coupling of the external field to the resonant field. Remarkably, the critical overlap fields are similar for n=1 and 2 fields with m >nq fields dominating the drive for resonant fields. Complementary experiments in RFX-Mod show fields with m 1 control, including the need for multiple rows of coils to control selected plasma parameters for specific functions (e.g., rotation control or ELM suppression). Optimal multi-harmonic (n=1 and n=2) error field control may be achieved using control algorithms that continuously respond to time-varying 3D field sources and plasma parameters. Supported by the US DOE under DE-FC02-04ER54698.

Artificial magnetic field for the space station (Protecting space stations in future space missions)

NASA Astrophysics Data System (ADS)

Ahmadi Tara, Miss

Problem Explanation Strong solar storms and cosmic rays make great disturbances for equip-ment outside the magnetosphere. Also these disturbances are so harmful for biological process of living cells. If one decides to stay more outside the Earth, one's healthy is in a great danger. To investigate space station situation against strong solar storms, 5 recent strong solar storms have been selected. Dst of these storms are more than -300 nT. Each one of these storms has an accurate danger percentage. These data has been shown in Tab I. Tab I. strong solar storms during 1989-2003 and their danger percentage for space equipments and astronauts on outside the magnetic field As has been shown in Tab I. these strong storms are so dangerous and make problem for human outside the Earth layers. Basic on [13] solar activities in next century will be more than this century. That paper shows that the average number of sunspots in this century is less than 77 and this average will be more than 150 sunspots in a century. So we have only 70 years to prepare a suitable space station in other wise building this centre wills has many problem such as health security and long travels. Method explanation Only method to face with energetic particles is magnetic field. Space station is bereft of strong magnetic field to protect herself from energetic particles that released from the Sun and other types of stars in other galaxies (cosmic rays). Therefore the existence of an artificial magnetic field is necessary, this is not important that this field will be for the space station or its inner space because this field performs as magnetosphere. It does not allow energetic particles to enter the field. Also this field loads up to solar magnetic field as magnetosphere. Position of this artificial field is not important because basic on the simulations this field could repulse 85.6Modeling Important feature of this artificial field is its situation against solar magnetic field, i.e. these fields always are anti-aligned because artificial field could change direction by itself basic on the situation of Sun. Relationship between artificial field and solar storm has two types: 1) Artifi-cial field loads up to solar storm's magnetic field and makes magnetic reconnection 2) artificial field repulses energetic solar particles. These below equations show situation of artificial field against magnetic reconnection with magnetic field of solar storm and repulsing particles. Basic on the volume of repulsed particles the strength of field could be: Each one of these storms has an accurate danger percentage. These data has been shown in Tab I. Tab I. strong solar storms during 1989-2003 and their danger percentage for space equipments and astronauts on outside the magnetic field As has been shown in Tab I. these strong storms are so dangerous and make problem for human outside the Earth layers. Basic on [13] solar activities in next century will be more than this century. That paper shows that the average number of sunspots in this century is less than 77 and this average will be more than 150 sunspots in a century. So we have only 70 years to prepare a suitable space station in other wise building this centre wills has many problem such as health security and long travels. Method explanation Only method to face with energetic particles is magnetic field. Space station is bereft of strong magnetic field to protect herself from energetic particles that released from the Sun and other types of stars in other galaxies (cosmic rays). Therefore the existence of an artificial magnetic field is necessary, this is not important that this field will be for the space station or its inner space because this field performs as magnetosphere. It does not allow energetic particles to enter the field. Also this field loads up to solar magnetic field as magnetosphere. Position of this artificial field is not important because basic on the simulations this field could repulse 85.6Modeling Important feature of this artificial field is its situation against solar magnetic field, i.e. these fields always are anti-aligned because artificial field could change direction by itself basic on the situation of Sun. Relationship between artificial field and solar storm has two types: 1) Artificial field loads up to solar storm's magnetic field and makes magnetic reconnection 2) ar-tificial field repulses energetic solar particles. These below equations show situation of artificial field against magnetic reconnection with magnetic field of solar storm and repulsing particles. Basic on the volume of repulsed particles the strength of field could be: General equation of artificial field: Equations of artificial field basic on the magnetic reconnection: Also equation of balance of electrical energy is: That , V and P are denoting respectively density, velocity and pressure. is plasma energy density. J= current density, Bo =artificial magnetic field, B,E=plasma magnetic and electric field. Vs=volume of a sphere with r radius and =resistance General equation of artificial field: Equations of artificial field basic on the magnetic reconnec-tion: Also equation of balance of electrical energy is: That , V and P are denoting respectively density, velocity and pressure. is plasma energy density. J= current density, Bo =artificial magnetic field, B,E=plasma magnetic and electric field. Vs=volume of a sphere with r radius and =resistance Results Tab II. Danger percentage of 5 strong solar storms for equipment and astronauts in the future space station within the influence on artificial field As has been shown in Tab II artificial magnetic field could pass great dangers of solar storms and protect space station wherever of free space. FIG.2) Upper panel shows X-ray flux at two wavelengths 0.5-4 ˚ and 1-8 ˚. Lower Panel shows Proton flux in various energy levels received on the Moon's A A surface from solar storm 2000(obtained from simulation) 0-14(UT) obtained from outside the field, 14-7(UT) obtained from receiver in the field, 7-0(UT) obtained from receiver behind in-strument Conclusion In this brief paper, I describe a way to protect future space station from energetic particles. This field could reduce damage of solar storms and cosmic rays that arrived to the space station outside the Earth magnetic field. This field performs as magnetosphere for space station. It could change its situation and make easy live on the space station. This strong magnetic field must be generated by low-temperature superconductors. They are suit-able material to use at generating a strong magnetic field. These materials could be used in the structure of spacecrafts during long duration space travels in future

Zero- to low-field MRI with averaging of concomitant gradient fields.

PubMed

Meriles, Carlos A; Sakellariou, Dimitris; Trabesinger, Andreas H; Demas, Vasiliki; Pines, Alexander

2005-02-08

Magnetic resonance imaging (MRI) encounters fundamental limits in circumstances in which the static magnetic field is not sufficiently strong to truncate unwanted, so-called concomitant components of the gradient field. This limitation affects the attainable optimal image fidelity and resolution most prominently in low-field imaging. In this article, we introduce the use of pulsed magnetic-field averaging toward relaxing these constraints. It is found that the image of an object can be retrieved by pulsed low fields in the presence of the full spatial variation of the imaging encoding gradient field even in the absence of the typical uniform high-field time-independent contribution. In addition, error-compensation schemes can be introduced through the application of symmetrized pulse sequences. Such schemes substantially mitigate artifacts related to evolution in strong magnetic-field gradients, magnetic fields that vary in direction and orientation, and imperfections of the applied field pulses.

Aspects of the Antisymmetric Tensor Field

NASA Astrophysics Data System (ADS)

Lahiri, Amitabha

1991-02-01

With the possible exception of gravitation, fundamental interactions are generally described by theories of point particles interacting via massless gauge fields. Since the advent of string theories the picture of physical interaction has changed to accommodate one in which extended objects interact with each other. The generalization of the gauge theories to extended objects leads to theories of antisymmetric tensor fields. At scales corresponding to present-day laboratory experiments one expects to see only point particles, their interactions modified by the presence of antisymmetric tensor fields in the theory. Therefore, in order to establish the validity of any theory with antisymmetric tensor fields one needs to look for manifestations of these fields at low energies. The principal problem of gauge theories is the failure to provide a suitable explanation for the generation of masses for the fields in the theory. While there is a known mechanism (spontaneous symmetry breaking) for generating masses for both the matter fields and the gauge fields, the lack of experimental evidence in support of an elementary scalar field suggests that one look for alternative ways of generating masses for the fields. The interaction of gauge fields with an antisymmetric tensor field seems to be an attractive way of doing so, especially since all indications point to the possibility that there will be no remnant degrees of freedom. On the other hand the interaction of such a field with black holes suggest an independent way of verifying the existence of such fields. In this dissertation the origins of the antisymmetric tensor field are discussed in terms of string theory. The interaction of black holes with such a field is discussed next. The last chapter discusses the effects of an antisymmetric tensor field on quantum electrodynamics when the fields are minimally coupled.

Modelling of induced electric fields based on incompletely known magnetic fields

NASA Astrophysics Data System (ADS)

Laakso, Ilkka; De Santis, Valerio; Cruciani, Silvano; Campi, Tommaso; Feliziani, Mauro

2017-08-01

Determining the induced electric fields in the human body is a fundamental problem in bioelectromagnetics that is important for both evaluation of safety of electromagnetic fields and medical applications. However, existing techniques for numerical modelling of induced electric fields require detailed information about the sources of the magnetic field, which may be unknown or difficult to model in realistic scenarios. Here, we show how induced electric fields can accurately be determined in the case where the magnetic fields are known only approximately, e.g. based on field measurements. The robustness of our approach is shown in numerical simulations for both idealized and realistic scenarios featuring a personalized MRI-based head model. The approach allows for modelling of the induced electric fields in biological bodies directly based on real-world magnetic field measurements.

Internal split field generator

DOEpatents

Thundat,; George, Thomas [Knoxville, TN; Van Neste, Charles W [Kingston, TN; Vass, Arpad Alexander [Oak Ridge, TN

2012-01-03

A generator includes a coil of conductive material. A stationary magnetic field source applies a stationary magnetic field to the coil. An internal magnetic field source is disposed within a cavity of the coil to apply a moving magnetic field to the coil. The stationary magnetic field interacts with the moving magnetic field to generate an electrical energy in the coil.

Potential of Field Education as Signature Pedagogy: The Field Director Role

ERIC Educational Resources Information Center

Lyter, Sharon C.

2012-01-01

In light of the assertion that field education is the signature pedagogy of social work education, this Internet-based study explores field director demographics and questions the fulfillment of this potential, examining BSW and MSW field education through the lens of the field director position. Field directors (159) and deans/directors (150)…

Correcting GOES-R Magnetometer Data for Stray Fields

NASA Technical Reports Server (NTRS)

Carter, Delano R.; Freesland, Douglas C.; Tadikonda, Sivakumara K.; Kronenwetter, Jeffrey; Todirita, Monica; Dahya, Melissa; Chu, Donald

2016-01-01

Time-varying spacecraft magnetic fields or stray fields are a problem for magnetometer systems. While constant fields can be removed with zero offset calibration, stray fields are difficult to distinguish from ambient field variations. Putting two magnetometers on a long boom and solving for both the ambient and stray fields can be a good idea, but this gradiometer solution is even more susceptible to noise than a single magnetometer. Unless the stray fields are larger than the magnetometer noise, simply averaging the two measurements is a more accurate approach. If averaging is used, it may be worthwhile to explicitly estimate and remove stray fields. Models and estimation algorithms are provided for solar array, arcjet and reaction wheel fields.

Twistor encoding of Lienard--Wiechert fields in Minkowski space-time

DOE Office of Scientific and Technical Information (OSTI.GOV)

Porter, J.R.

1985-03-01

The twistor encoding of the anti-self-dual Lienard--Wiechert field on Minkowski space-time yields a considerably richer structure than that of the Coulomb field encoding due to the presence of a nonzero radiation field. The combination of advanced and retarded transverse fields together with the longitudinal field and the individual aspects of these fields provides this structure. Higher-order longitudinal moments can be incorporated so that general longitudinal fields can be given a twistor description.

Prequantum classical statistical field theory: background field as a source of everything?

NASA Astrophysics Data System (ADS)

Khrennikov, Andrei

2011-07-01

Prequantum classical statistical field theory (PCSFT) is a new attempt to consider quantum mechanics (QM) as an emergent phenomenon, cf. with De Broglie's "double solution" approach, Bohmian mechanics, stochastic electrodynamics (SED), Nelson's stochastic QM and its generalization by Davidson, 't Hooft's models and their development by Elze. PCSFT is a comeback to a purely wave viewpoint on QM, cf. with early Schrodinger. There is no quantum particles at all, only waves. In particular, photons are simply wave-pulses of the classical electromagnetic field, cf. SED. Moreover, even massive particles are special "prequantum fields": the electron field, the neutron field, and so on. PCSFT claims that (sooner or later) people will be able to measure components of these fields: components of the "photonic field" (the classical electromagnetic field of low intensity), electronic field, neutronic field, and so on. At the moment we are able to produce quantum correlations as correlations of classical Gaussian random fields. In this paper we are interested in mathematical and physical reasons of usage of Gaussian fields. We consider prequantum signals (corresponding to quantum systems) as composed of a huge number of wave-pulses (on very fine prequantum time scale). We speculate that the prequantum background field (the field of "vacuum fluctuations") might play the role of a source of such pulses, i.e., the source of everything.

Effects of the reconnection electric field on crescent electron distribution functions in asymmetric guide field reconnection

NASA Astrophysics Data System (ADS)

Bessho, N.; Chen, L. J.; Hesse, M.; Wang, S.

2017-12-01

In asymmetric reconnection with a guide field in the Earth's magnetopause, electron motion in the electron diffusion region (EDR) is largely affected by the guide field, the Hall electric field, and the reconnection electric field. The electron motion in the EDR is neither simple gyration around the guide field nor simple meandering motion across the current sheet. The combined meandering motion and gyration has essential effects on particle acceleration by the in-plane Hall electric field (existing only in the magnetospheric side) and the out-of-plane reconnection electric field. We analyze electron motion and crescent-shaped electron distribution functions in the EDR in asymmetric guide field reconnection, and perform 2-D particle-in-cell (PIC) simulations to elucidate the effect of reconnection electric field on electron distribution functions. Recently, we have analytically expressed the acceleration effect due to the reconnection electric field on electron crescent distribution functions in asymmetric reconnection without a guide field (Bessho et al., Phys. Plasmas, 24, 072903, 2017). We extend the theory to asymmetric guide field reconnection, and predict the crescent bulge in distribution functions. Assuming 1D approximation of field variations in the EDR, we derive the time period of oscillatory electron motion (meandering + gyration) in the EDR. The time period is expressed as a hybrid of the meandering period and the gyro period. Due to the guide field, electrons not only oscillate along crescent-shaped trajectories in the velocity plane perpendicular to the antiparallel magnetic fields, but also move along parabolic trajectories in the velocity plane coplanar with magnetic field. The trajectory in the velocity space gradually shifts to the acceleration direction by the reconnection electric field as multiple bounces continue. Due to the guide field, electron distributions for meandering particles are bounded by two paraboloids (or hyperboloids) in the velocity space. We compare theory and PIC simulation results of the velocity shift of crescent distribution functions based on the derived time period of bounce motion in a guide field. Theoretical predictions are applied to electron distributions observed by MMS in magnetopause reconnection to estimate the reconnection electric field.

External split field generator

DOEpatents

Thundat, Thomas George [Knoxville, TN; Van Neste, Charles W [Kingston, TN; Vass, Arpad Alexander [Oak Ridge, TN

2012-02-21

A generator includes a coil disposed about a core. A first stationary magnetic field source may be disposed on a first end portion of the core and a second stationary magnetic field source may be disposed on a second end portion of core. The first and second stationary magnetic field sources apply a stationary magnetic field to the coil. An external magnetic field source may be disposed outside the coil to apply a moving magnetic field to the coil. Electrical energy is generated in response to an interaction between the coil, the moving magnetic field, and the stationary magnetic field.

Gaugeon formalism for the second-rank antisymmetric tensor gauge fields

NASA Astrophysics Data System (ADS)

Aochi, Masataka; Endo, Ryusuke; Miura, Hikaru

2018-02-01

We present a BRST symmetric gaugeon formalism for the second-rank antisymmetric tensor gauge fields. A set of vector gaugeon fields is introduced as a quantum gauge freedom. One of the gaugeon fields satisfies a higher-derivative field equation; this property is necessary to change the gauge-fixing parameter of the antisymmetric tensor gauge field. A naive Lagrangian for the vector gaugeon fields is itself invariant under a gauge transformation for the vector gaugeon field. The Lagrangian of our theory includes the gauge-fixing terms for the gaugeon fields and corresponding Faddeev-Popov ghost terms.

Elliptic-symmetry vector optical fields.

PubMed

Pan, Yue; Li, Yongnan; Li, Si-Min; Ren, Zhi-Cheng; Kong, Ling-Jun; Tu, Chenghou; Wang, Hui-Tian

2014-08-11

We present in principle and demonstrate experimentally a new kind of vector fields: elliptic-symmetry vector optical fields. This is a significant development in vector fields, as this breaks the cylindrical symmetry and enriches the family of vector fields. Due to the presence of an additional degrees of freedom, which is the interval between the foci in the elliptic coordinate system, the elliptic-symmetry vector fields are more flexible than the cylindrical vector fields for controlling the spatial structure of polarization and for engineering the focusing fields. The elliptic-symmetry vector fields can find many specific applications from optical trapping to optical machining and so on.

40 CFR 174.502 - Bacillus thuringiensis Cry1A.105 protein; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... or on the food and feed commodities of corn; corn, field, flour; corn, field, forage; corn, field, grain; corn, field, grits; corn, field, meal; corn, field, refined oil; corn, field, stover; corn, sweet, forage; corn, sweet, kernel plus cob with husk removed; corn, sweet, stover; and corn, pop, grain and...

40 CFR 174.502 - Bacillus thuringiensis Cry1A.105 protein; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... or on the food and feed commodities of corn; corn, field, flour; corn, field, forage; corn, field, grain; corn, field, grits; corn, field, meal; corn, field, refined oil; corn, field, stover; corn, sweet, forage; corn, sweet, kernel plus cob with husk removed; corn, sweet, stover; and corn, pop, grain and...

40 CFR 174.502 - Bacillus thuringiensis Cry1A.105 protein; exemption from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... or on the food and feed commodities of corn; corn, field, flour; corn, field, forage; corn, field, grain; corn, field, grits; corn, field, meal; corn, field, refined oil; corn, field, stover; corn, sweet, forage; corn, sweet, kernel plus cob with husk removed; corn, sweet, stover; and corn, pop, grain and...

Command Post Program Study. Volume 1 - Main Report

DTIC Science & Technology

1973-03-01

Field Manual 30-9, Military Intelligence Battalion - Field Am. Washington: March 1968. _ Field Manual 32-20, Electronic Warfare. Washington: 14...Mechanized). A-18 TOE 30-88T, Military Intelligence Support Detachment, Military Intelligence Battalion, Field Army. TOE 30-206T, Headquarters and... Field Manual 30-9, Military Intelligence Battalion - Field Army. Washington: March 1968. _ Field Manual 32-20, Electronic Warfare. Washington: 14

The generation and dissipation of solar and galactic magnetic fields.

NASA Technical Reports Server (NTRS)

Parker, E. N.

1973-01-01

Turbulent diffusion of magnetic field plays an essential role in the generation of magnetic field in most astrophysical bodies. Review of what can be proved and what can be believed about the turbulent diffusion of magnetic field. Observations indicate the dissipation of magnetic field at rates that can be understood only in terms of turbulent diffusion. Theory shows that a large-scale weak magnetic field diffuses in a turbulent flow in the same way that smoke is mixed throughout the fluid by the turbulence. The small-scale fields (produced from the large-scale field by the turbulence) are limited in their growth by reconnection of field lines at neutral points, so that the turbulent mixing of field and fluid is not halted by them. Altogether, it appears that the mixing of field and fluid in the observed turbulent motions in the sun and in the Galaxy is unavoidable. Turbulent diffusion causes decay of the general solar fields in a decade or so, and of the galactic field in 100 m.y. to 1 b.y. It is concluded that continual dynamo action is implied by the observed existence of the fields.

Auroral zone electric fields from DE 1 and 2 at magnetic conjunctions

NASA Technical Reports Server (NTRS)

Weimer, D. R.; Goertz, C. K.; Gurnett, D. A.; Maynard, N. C.; Burch, J. L.

1985-01-01

Nearly simultaneous measurements of auroral zone electric fields are obtained by the Dynamics Explorer spacecraft at altitudes below 900 km and above 4,500 km during magnetic conjunctions. The measured electric fields are usually perpendicular to the magnetic field lines. The north-south meridional electric fields are projected to a common altitude by a mapping function which accounts for the convergence of the magnetic field lines. When plotted as a function of invariant latitude, graphs of the projected electric fields measured by both DE-1 and DE-2 show that the large-scale electric field is the same at both altitudes, as expected. Superimposed on the large-scale fields, however, are small-scale features with wavelengths less than 100 km which are larger in magnitude at the higher altitude. Fourier transforms of the electric fields show that the magnitudes depend on wavelength. Outside of the auroral zone the electric field spectrums are nearly identical. But within the auroral zone the high and low altitude electric fields have a ratio which increases with the reciprocal of the wavelength. The small-scale electric field variations are associated with field-aligned currents. These currents are measured with both a plasma instrument and magnetometer on DE-1.

Weaving Knotted Vector Fields with Tunable Helicity.

PubMed

Kedia, Hridesh; Foster, David; Dennis, Mark R; Irvine, William T M

2016-12-30

We present a general construction of divergence-free knotted vector fields from complex scalar fields, whose closed field lines encode many kinds of knots and links, including torus knots, their cables, the figure-8 knot, and its generalizations. As finite-energy physical fields, they represent initial states for fields such as the magnetic field in a plasma, or the vorticity field in a fluid. We give a systematic procedure for calculating the vector potential, starting from complex scalar functions with knotted zero filaments, thus enabling an explicit computation of the helicity of these knotted fields. The construction can be used to generate isolated knotted flux tubes, filled by knots encoded in the lines of the vector field. Lastly, we give examples of manifestly knotted vector fields with vanishing helicity. Our results provide building blocks for analytical models and simulations alike.

Time-dependent analysis of the mixed-field orientation of molecules without rotational symmetry

NASA Astrophysics Data System (ADS)

Thesing, Linda V.; Küpper, Jochen; González-Férez, Rosario

2017-06-01

We present a theoretical study of the mixed-field orientation of molecules without rotational symmetry. The time-dependent one-dimensional and three-dimensional orientation of a thermal ensemble of 6-chloropyridazine-3-carbonitrile molecules in combined linearly or elliptically polarized laser fields and tilted dc electric fields is computed. The results are in good agreement with recent experimental results of one-dimensional orientation for weak dc electric fields [J. L. Hansen, J. Chem. Phys. 139, 234313 (2013)]. Moreover, they predict that using elliptically polarized laser fields or strong dc fields, three-dimensional orientation is obtained. The field-dressed dynamics of excited rotational states is characterized by highly non-adiabatic effects. We analyze the sources of these non-adiabatic effects and investigate their impact on the mixed-field orientation for different field configurations in mixed-field-orientation experiments.

Large-scale properties of the interplanetary magnetic field

NASA Technical Reports Server (NTRS)

Schatten, K. H.

1972-01-01

Early theoretical work of Parker is presented along with the observational evidence supporting his Archimedes spiral model. Variations present in the interplanetary magnetic field from the spiral angle are related to structures in the solar wind. The causes of these structures are found to be either nonuniform radial solar wind flow or the time evolution of the photospheric field. Coronal magnetic models are related to the connection between the solar magnetic field and the interplanetary magnetic field. Direct extension of the solar field-magnetic nozzle controversy is discussed along with the coronal magnetic models. Effects of active regions on the interplanetary magnetic field is discussed with particular reference to the evolution of interplanetary sectors. Interplanetary magnetic field magnitude variations are shown throughout the solar cycle. The percentage of time the field magnitude is greater than 10 gamma is shown to closely parallel sunspot number. The sun's polar field influence on the interplanetary field and alternative views of the magnetic field structure out of the ecliptic plane are presented. In addition, a variety of significantly different interplanetary field structures are discussed.

Simple estimation of induced electric fields in nervous system tissues for human exposure to non-uniform electric fields at power frequency

NASA Astrophysics Data System (ADS)

Tarao, Hiroo; Miyamoto, Hironobu; Korpinen, Leena; Hayashi, Noriyuki; Isaka, Katsuo

2016-06-01

Most results regarding induced current in the human body related to electric field dosimetry have been calculated under uniform field conditions. We have found in previous work that a contact current is a more suitable way to evaluate induced electric fields, even in the case of exposure to non-uniform fields. If the relationship between induced currents and external non-uniform fields can be understood, induced electric fields in nervous system tissues may be able to be estimated from measurements of ambient non-uniform fields. In the present paper, we numerically calculated the induced electric fields and currents in a human model by considering non-uniform fields based on distortion by a cubic conductor under an unperturbed electric field of 1 kV m-1 at 60 Hz. We investigated the relationship between a non-uniform external electric field with no human present and the induced current through the neck, and the relationship between the current through the neck and the induced electric fields in nervous system tissues such as the brain, heart, and spinal cord. The results showed that the current through the neck can be formulated by means of an external electric field at the central position of the human head, and the distance between the conductor and the human model. As expected, there is a strong correlation between the current through the neck and the induced electric fields in the nervous system tissues. The combination of these relationships indicates that induced electric fields in these tissues can be estimated solely by measurements of the external field at a point and the distance from the conductor.

Video image stabilization and registration--plus

NASA Technical Reports Server (NTRS)

Hathaway, David H. (Inventor)

2009-01-01

A method of stabilizing a video image displayed in multiple video fields of a video sequence includes the steps of: subdividing a selected area of a first video field into nested pixel blocks; determining horizontal and vertical translation of each of the pixel blocks in each of the pixel block subdivision levels from the first video field to a second video field; and determining translation of the image from the first video field to the second video field by determining a change in magnification of the image from the first video field to the second video field in each of horizontal and vertical directions, and determining shear of the image from the first video field to the second video field in each of the horizontal and vertical directions.

Improving chemical shift encoding‐based water–fat separation based on a detailed consideration of magnetic field contributions

PubMed Central

Ruschke, Stefan; Eggers, Holger; Meineke, Jakob; Rummeny, Ernst J.; Karampinos, Dimitrios C.

2018-01-01

Purpose To improve the robustness of existing chemical shift encoding‐based water–fat separation methods by incorporating a priori information of the magnetic field distortions in complex‐based water–fat separation. Methods Four major field contributions are considered: inhomogeneities of the scanner magnet, the shim field, an object‐based field map estimate, and a residual field. The former two are completely determined by spherical harmonic expansion coefficients directly available from the magnetic resonance (MR) scanner. The object‐based field map is forward simulated from air–tissue interfaces inside the field of view (FOV). The missing residual field originates from the object outside the FOV and is investigated by magnetic field simulations on a numerical whole body phantom. In vivo the spatially linear first‐order component of the residual field is estimated by measuring echo misalignments after demodulation of other field contributions resulting in a linear residual field. Gradient echo datasets of the cervical and the ankle region without and with shimming were acquired, where all four contributions were incorporated in the water–fat separation with two algorithms from the ISMRM water–fat toolbox and compared to water–fat separation with less incorporated field contributions. Results Incorporating all four field contributions as demodulation steps resulted in reduced temporal and spatial phase wraps leading to almost swap‐free water–fat separation results in all datasets. Conclusion Demodulating estimates of major field contributions reduces the phase evolution to be driven by only small differences in local tissue susceptibility, which supports the field smoothness assumption of existing water–fat separation techniques. PMID:29424458

Exploration of solar photospheric magnetic field data sets using the UCSD tomography

NASA Astrophysics Data System (ADS)

Jackson, B. V.; Yu, H.-S.; Buffington, A.; Hick, P. P.; Nishimura, N.; Nozaki, N.; Tokumaru, M.; Fujiki, K.; Hayashi, K.

2016-12-01

This article investigates the use of two different types of National Solar Observatory magnetograms and two different coronal field modeling techniques over 10 years. Both the "open-field" Current Sheet Source Surface (CSSS) and a "closed-field" technique using CSSS modeling are compared. The University of California, San Diego, tomographic modeling, using interplanetary scintillation data from Japan, provides the global velocities to extrapolate these fields outward, which are then compared with fields measured in situ near Earth. Although the open-field technique generally gives a better result for radial and tangential fields, we find that a portion of the closed extrapolated fields measured in situ near Earth comes from the direct outward mapping of these fields in the low solar corona. All three closed-field components are nonzero at 1 AU and are compared with the appropriate magnetometer values. A significant positive correlation exists between these closed-field components and the in situ measurements over the last 10 years. We determine that a small fraction of the static low-coronal component flux, which includes the Bn (north-south) component, regularly escapes from closed-field regions. The closed-field flux fraction varies by about a factor of 3 from a mean value during this period, relative to the magnitude of the field components measured in situ near Earth, and maximizes in 2014. This implies that a relatively more efficient process for closed-flux escape occurs near solar maximum. We also compare and find that the popular Potential Field Source Surface and CSSS model closed fields are nearly identical in sign and strength.

Manipulation of positron orbits in a dipole magnetic field with fluctuating electric fields

NASA Astrophysics Data System (ADS)

Saitoh, H.; Horn-Stanja, J.; Nißl, S.; Stenson, E. V.; Hergenhahn, U.; Pedersen, T. Sunn; Singer, M.; Dickmann, M.; Hugenschmidt, C.; Stoneking, M. R.; Danielson, J. R.; Surko, C. M.

2018-01-01

We report the manipulation of positron orbits in a toroidal dipole magnetic field configuration realized with electric fields generated by segmented electrodes. When the toroidal circulation motion of positrons in the dipole field is coupled with time-varying electric fields generated by azimuthally segmented outer electrodes, positrons undergo oscillations of their radial positions. This enables quick manipulation of the spatial profiles of positrons in a dipole field trap by choosing appropriate frequency, amplitude, phase, and gating time of the electric fields. According to numerical orbit analysis, we applied these electric fields to positrons injected from the NEPOMUC slow positron facility into a prototype dipole field trap experiment with a permanent magnet. Measurements with annihilation γ-rays clearly demonstrated the efficient compression effects of positrons into the strong magnetic field region of the dipole field configuration. This positron manipulation technique can be used as one of essential tools for future experiments on the formation of electron-positron plasmas.

Vibrational near-field mapping of planar and buried three-dimensional plasmonic nanostructures

PubMed Central

Dregely, Daniel; Neubrech, Frank; Duan, Huigao; Vogelgesang, Ralf; Giessen, Harald

2013-01-01

Nanoantennas confine electromagnetic fields at visible and infrared wavelengths to volumes of only a few cubic nanometres. Assessing their near-field distribution offers fundamental insight into light–matter coupling and is of special interest for applications such as radiation engineering, attomolar sensing and nonlinear optics. Most experimental approaches to measure near-fields employ either diffraction-limited far-field methods or intricate near-field scanning techniques. Here, using diffraction-unlimited far-field spectroscopy in the infrared, we directly map the intensity of the electric field close to plasmonic nanoantennas. We place a patch of probe molecules with 10 nm accuracy at different locations in the near-field of a resonant antenna and extract the molecular vibrational excitation. We map the field intensity along a dipole antenna and gap-type antennas. Moreover, this method is able to assess the near-field intensity of complex buried plasmonic structures. We demonstrate this by measuring for the first time the near-field intensity of a three-dimensional plasmonic electromagnetically induced transparency structure. PMID:23892519

Non-uniform refractive index field measurement based on light field imaging technique

NASA Astrophysics Data System (ADS)

Du, Xiaokun; Zhang, Yumin; Zhou, Mengjie; Xu, Dong

2018-02-01

In this paper, a method for measuring the non-uniform refractive index field based on the light field imaging technique is proposed. First, the light field camera is used to collect the four-dimensional light field data, and then the light field data is decoded according to the light field imaging principle to obtain image sequences with different acquisition angles of the refractive index field. Subsequently PIV (Particle Image Velocimetry) technique is used to extract ray offset of each image. Finally, the distribution of non-uniform refractive index field can be calculated by inversing the deflection of light rays. Compared with traditional optical methods which require multiple optical detectors from multiple angles to synchronously collect data, the method proposed in this paper only needs a light field camera and shoot once. The effectiveness of the method has been verified by the experiment which quantitatively measures the distribution of the refractive index field above the flame of the alcohol lamp.

Compressive light field imaging

NASA Astrophysics Data System (ADS)

Ashok, Amit; Neifeld, Mark A.

2010-04-01

Light field imagers such as the plenoptic and the integral imagers inherently measure projections of the four dimensional (4D) light field scalar function onto a two dimensional sensor and therefore, suffer from a spatial vs. angular resolution trade-off. Programmable light field imagers, proposed recently, overcome this spatioangular resolution trade-off and allow high-resolution capture of the (4D) light field function with multiple measurements at the cost of a longer exposure time. However, these light field imagers do not exploit the spatio-angular correlations inherent in the light fields of natural scenes and thus result in photon-inefficient measurements. Here, we describe two architectures for compressive light field imaging that require relatively few photon-efficient measurements to obtain a high-resolution estimate of the light field while reducing the overall exposure time. Our simulation study shows that, compressive light field imagers using the principal component (PC) measurement basis require four times fewer measurements and three times shorter exposure time compared to a conventional light field imager in order to achieve an equivalent light field reconstruction quality.

Horizontal electric fields from lightning return strokes

NASA Technical Reports Server (NTRS)

Thomson, E. M.; Medelius, P. J.; Rubinstein, M.; Uman, M. A.; Johnson, J.

1988-01-01

An experiment to measure simultaneously the wideband horizontal and vertical electric fields from lightning return strokes is described. Typical wave shapes of the measured horizontal and vertical fields are presented, and the horizontal fields are characterized. The measured horizontal fields are compared with calculated horizontal fields obtained by applying the wavetilt formula to the vertical fields. The limitations and sources of error in the measurement technique are discussed.

Bats Respond to Very Weak Magnetic Fields

PubMed Central

Tian, Lan-Xiang; Pan, Yong-Xin; Metzner, Walter; Zhang, Jin-Shuo; Zhang, Bing-Fang

2015-01-01

How animals, including mammals, can respond to and utilize the direction and intensity of the Earth’s magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae) can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths occurred during geomagnetic excursions or polarity reversals and thus may have played an important role in the evolution of a magnetic sense. We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north. As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north. When the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT), despite the fact that the artificial field orientation was opposite to the natural geomagnetic field (P<0.05). Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength. This high sensitivity to magnetic fields may explain how magnetic orientation could have evolved in bats even as the Earth’s magnetic field strength varied and the polarity reversed tens of times over the past fifty million years. PMID:25922944

Bats respond to very weak magnetic fields.

PubMed

Tian, Lan-Xiang; Pan, Yong-Xin; Metzner, Walter; Zhang, Jin-Shuo; Zhang, Bing-Fang

2015-01-01

How animals, including mammals, can respond to and utilize the direction and intensity of the Earth's magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae) can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths occurred during geomagnetic excursions or polarity reversals and thus may have played an important role in the evolution of a magnetic sense. We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north. As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north. When the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT), despite the fact that the artificial field orientation was opposite to the natural geomagnetic field (P<0.05). Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength. This high sensitivity to magnetic fields may explain how magnetic orientation could have evolved in bats even as the Earth's magnetic field strength varied and the polarity reversed tens of times over the past fifty million years.

Oil, gas field growth projections: Wishful thinking or reality?

USGS Publications Warehouse

Attanasi, E.D.; Mast, R.F.; Root, D.H.

1999-01-01

The observed `field growth' for the period from 1992 through 1996 with the US Geological Survey's (USGS) predicted field growth for the same period are compared. Known field recovery of field size is defined as the sum of past cumulative field production and the field's proved reserves. Proved reserves are estimated quantities of hydrocarbons which geologic and engineering data demonstrate with reasonable certainty to recoverable from known fields under existing economic and operating conditions. Proved reserve estimates calculated with this definition are typically conservative. The modeling approach used by the USGS to characterize `field growth phenomena' is statistical rather that geologic in nature.

Active stabilization of error field penetration via control field and bifurcation of its stable frequency range

NASA Astrophysics Data System (ADS)

Inoue, S.; Shiraishi, J.; Takechi, M.; Matsunaga, G.; Isayama, A.; Hayashi, N.; Ide, S.

2017-11-01

An active stabilization effect of a rotating control field against an error field penetration is numerically studied. We have developed a resistive magnetohydrodynamic code ‘AEOLUS-IT’, which can simulate plasma responses to rotating/static external magnetic field. Adopting non-uniform flux coordinates system, the AEOLUS-IT simulation can employ high magnetic Reynolds number condition relevant to present tokamaks. By AEOLUS-IT, we successfully clarified the stabilization mechanism of the control field against the error field penetration. Physical processes of a plasma rotation drive via the control field are demonstrated by the nonlinear simulation, which reveals that the rotation amplitude at a resonant surface is not a monotonic function of the control field frequency, but has an extremum. Consequently, two ‘bifurcated’ frequency ranges of the control field are found for the stabilization of the error field penetration.

The Theory of Quantized Fields. II

DOE R&D Accomplishments Database

Schwinger, J.

1951-01-01

The arguments leading to the formulation of the Action Principle for a general field are presented. In association with the complete reduction of all numerical matrices into symmetrical and anti-symmetrical parts, the general field is decomposed into two sets, which are identified with Bose-Einstein and Fermi-Dirac fields. The spin restriction on the two kinds of fields is inferred from the time reflection invariance requirement. The consistency of the theory is verified in terms of a criterion involving the various generators of infinitesimal transformations. Following a discussion of charged fields, the electromagnetic field is introduced to satisfy the postulate of general gauge invariance. As an aspect of the latter, it is recognized that the electromagnetic field and charged fields are not kinematically independent. After a discussion of the field-strength commutation relations, the independent dynamical variable of the electromagnetic field are exhibited in terms of a special gauge.

Static electric fields modify the locomotory behaviour of cockroaches.

PubMed

Jackson, Christopher W; Hunt, Edmund; Sharkh, Suleiman; Newland, Philip L

2011-06-15

Static electric fields are found throughout the environment and there is growing interest in how electric fields influence insect behaviour. Here we have analysed the locomotory behaviour of cockroaches (Periplaneta americana) in response to static electric fields at levels equal to and above those found in the natural environment. Walking behaviour (including velocity, distance moved, turn angle and time spent walking) were analysed as cockroaches approached an electric field boundary in an open arena, and also when continuously exposed to an electric field. On approaching an electric field boundary, the greater the electric field strength the more likely a cockroach would be to turn away from, or be repulsed by, the electric field. Cockroaches completely exposed to electric fields showed significant changes in locomotion by covering less distance, walking slowly and turning more often. This study highlights the importance of electric fields on the normal locomotory behaviour of insects.

Getting Geology Students Into the Field

NASA Astrophysics Data System (ADS)

Nocerino, J.

2011-12-01

The importance of field schools to practicing geologists is unquestionable; yet, the opportunities to experience field geology are dwindling. The Geological Society of America (GSA), in cooperation with ExxonMobil, are currently offering three programs to support and encourage field geology. The GSA/ExxonMobil Bighorn Basin Field award is a field seminar in the Bighorn Basin of north-central Wyoming emphasizing multi-disciplinary integrated basin analysis. The GSA/ExxonMobil Field Camp Scholar Award provides undergraduate students 2,000 each to attend the field camp of their choice based on diversity, economic/financial need, and merit. Finally, the GSA/ExxonMobil Field Camp Excellence Award provides one geologic field camp leader an award of 10,000 to assist with their summer field camp season based on safety awareness, diversity, and technical excellence. This non-profit/industry collaboration has proven very successful and in 2011 over 300 geology students and professors have applied for these awards.

The Primordial Origin Model of Magnetic Fields in Spiral Galaxies

NASA Astrophysics Data System (ADS)

Sofue, Yoshiaki; Machida, Mami; Kudoh, Takahiro

2010-10-01

We propose a primordial-origin model for composite configurations of global magnetic fields in spiral galaxies. We show that a uniform tilted magnetic field wound up into a rotating disk galaxy can evolve into composite magnetic configurations comprising bisymmetric spiral (S = BSS), axisymmetric spiral (A = ASS), plane-reversed spiral (PR), and/or ring (R) fields in the disk, and vertical (V) fields in the center. By MHD simulations we show that these composite galactic fields are indeed created from a weak primordial uniform field, and that different configurations can co-exist in the same galaxy. We show that spiral fields trigger the growth of two-armed gaseous arms. The centrally accumulated vertical fields are twisted and produce a jet toward the halo. We found that the more vertical was the initial uniform field, the stronger was the formed magnetic field in the galactic disk.