None
2016-07-12
âmasslessâ modes (here spin-waves), which are the ancestors of the NG bosons discussed below. Fluctuations of the order parameter (the magnetization) are described by a âmassiveâ SBS mode. - In field theory, Nambu showed that broken chiral symmetry from a spontaneous generation of hadron masses induces massless pseudoscalar modes (identified with a massless limit of pion fields). This illustrates a general phenomenon made explicit by Goldstone: massless Nambu-Goldstone (NG) bosons are a necessary concomitant of spontaneously broken continuous symmetries. Massive SBS scalars bosons describe, as in phase transitions, the fluctuations of the SBS order parameters. - In 1964, with Robert Brout, we discovered a mechanism based on SBS by which short range interactions are generated from long range ones. A similar proposal was then made independently by Higgs in a different approach. Qualitatively, our mechanism works as follows. The long range fundamental electromagnetic and gravitational interactions are governed by extended symmetries,called gauge symmetries, which were supposed to guarantee that the elementary field constituents which transmit the forces, photons or gravitons, be massless. We considered a generalization of the electromagnetic âvectorâ field, known as Yang-Mills fields, and coupled them to fields which acquire from SBS constant values in the vacuum. These fields pervade space, as did magnetization, but they have no spatial orientation: they are âscalarââ fields. The vector Yang-Mills fields which interact with the scalar fields become massive and hence the forces they mediate become short ranged. We also showed that the mechanism can survive in absence of elementary scalar fields. - Because of the extended symmetries, the nature of SBS is profoundly altered: the NG fields are absorbed into the massive vector Yang-Mills fields and restore the gauge symmetry. This has a dramatic consequence. To confront
2011-02-24
massless” modes (here spin-waves), which are the ancestors of the NG bosons discussed below. Fluctuations of the order parameter (the magnetization) are described by a “massive” SBS mode. - In field theory, Nambu showed that broken chiral symmetry from a spontaneous generation of hadron masses induces massless pseudoscalar modes (identified with a massless limit of pion fields). This illustrates a general phenomenon made explicit by Goldstone: massless Nambu-Goldstone (NG) bosons are a necessary concomitant of spontaneously broken continuous symmetries. Massive SBS scalars bosons describe, as in phase transitions, the fluctuations of the SBS order parameters. - In 1964, with Robert Brout, we discovered a mechanism based on SBS by which short range interactions are generated from long range ones. A similar proposal was then made independently by Higgs in a different approach. Qualitatively, our mechanism works as follows. The long range fundamental electromagnetic and gravitational interactions are governed by extended symmetries,called gauge symmetries, which were supposed to guarantee that the elementary field constituents which transmit the forces, photons or gravitons, be massless. We considered a generalization of the electromagnetic “vector” field, known as Yang-Mills fields, and coupled them to fields which acquire from SBS constant values in the vacuum. These fields pervade space, as did magnetization, but they have no spatial orientation: they are “scalar’’ fields. The vector Yang-Mills fields which interact with the scalar fields become massive and hence the forces they mediate become short ranged. We also showed that the mechanism can survive in absence of elementary scalar fields. - Because of the extended symmetries, the nature of SBS is profoundly altered: the NG fields are absorbed into the massive vector Yang-Mills fields and restore the gauge symmetry. This has a dramatic consequence. To confront precision experiments, the mechanism should be
Spontaneously Broken Gauge Symmetry in a Bose Gas with Constant Particle Number
NASA Astrophysics Data System (ADS)
Schelle, A.
The interplay between spontaneously broken gauge symmetries and Bose-Einstein condensation has long been controversially discussed in science, since the equations of motion are invariant under phase transformations. Within the present model, it is illustrated that spontaneous symmetry breaking appears as a non-local process in position space, but within disjoint subspaces of the underlying Hilbert space. Numerical simulations show that it is the symmetry of the relative phase distribution between condensate and non-condensate quantum fields which is spontaneously broken when passing the critical temperature for Bose-Einstein condensation. Since the total number of gas particles remains constant over time, the global U(1)-gauge symmetry of the system is preserved.
Weakly broken galileon symmetry
Pirtskhalava, David; Santoni, Luca; Trincherini, Enrico; Vernizzi, Filippo
2015-09-01
Effective theories of a scalar ϕ invariant under the internal galileon symmetryϕ→ϕ+b{sub μ}x{sup μ} have been extensively studied due to their special theoretical and phenomenological properties. In this paper, we introduce the notion of weakly broken galileon invariance, which characterizes the unique class of couplings of such theories to gravity that maximally retain their defining symmetry. The curved-space remnant of the galileon’s quantum properties allows to construct (quasi) de Sitter backgrounds largely insensitive to loop corrections. We exploit this fact to build novel cosmological models with interesting phenomenology, relevant for both inflation and late-time acceleration of the universe.
Broken Symmetries and Magnetic Dynamos
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2007-01-01
Phase space symmetries inherent in the statistical theory of ideal magnetohydrodynamic (MHD) turbulence are known to be broken dynamically to produce large-scale coherent magnetic structure. Here, results of a numerical study of decaying MHD turbulence are presented that show large-scale coherent structure also arises and persists in the presence of dissipation. Dynamically broken symmetries in MHD turbulence may thus play a fundamental role in the dynamo process.
Invariants of broken discrete symmetries.
Kalozoumis, P A; Morfonios, C; Diakonos, F K; Schmelcher, P
2014-08-01
The parity and Bloch theorems are generalized to the case of broken global symmetry. Local inversion or translation symmetries in one dimension are shown to yield invariant currents that characterize wave propagation. These currents map the wave function from an arbitrary spatial domain to any symmetry-related domain. Our approach addresses any combination of local symmetries, thus applying, in particular, to acoustic, optical, and matter waves. Nonvanishing values of the invariant currents provide a systematic pathway to the breaking of discrete global symmetries.
Invariants of Broken Discrete Symmetries
NASA Astrophysics Data System (ADS)
Kalozoumis, P. A.; Morfonios, C.; Diakonos, F. K.; Schmelcher, P.
2014-08-01
The parity and Bloch theorems are generalized to the case of broken global symmetry. Local inversion or translation symmetries in one dimension are shown to yield invariant currents that characterize wave propagation. These currents map the wave function from an arbitrary spatial domain to any symmetry-related domain. Our approach addresses any combination of local symmetries, thus applying, in particular, to acoustic, optical, and matter waves. Nonvanishing values of the invariant currents provide a systematic pathway to the breaking of discrete global symmetries.
Gauge symmetry from decoupling
NASA Astrophysics Data System (ADS)
Wetterich, C.
2017-02-01
Gauge symmetries emerge from a redundant description of the effective action for light degrees of freedom after the decoupling of heavy modes. This redundant description avoids the use of explicit constraints in configuration space. For non-linear constraints the gauge symmetries are non-linear. In a quantum field theory setting the gauge symmetries are local and can describe Yang-Mills theories or quantum gravity. We formulate gauge invariant fields that correspond to the non-linear light degrees of freedom. In the context of functional renormalization gauge symmetries can emerge if the flow generates or preserves large mass-like terms for the heavy degrees of freedom. They correspond to a particular form of gauge fixing terms in quantum field theories.
Broken symmetries in multilayered perceptrons
NASA Astrophysics Data System (ADS)
Barkai, E.; Hansel, D.; Sompolinsky, H.
1992-03-01
. The theoretical prediction (for K=3) is in excellent agreement with the numerical estimate based on an exhaustive search in the space of solutions for small N. These results indicate that in the binary case there is no RSB in the space of solutions below the maximal capacity. In the fully connected architecture, the solution's phase space has a global permutation symmetry (PS) reflecting the invariance under permuting the hidden units. The order parameters that signal the spontaneous breaking of this symmetry are defined. The RS theory shows that for small α the PS is maintained. For larger values of α<αc the symmetry is broken, inplying the breaking of the solution space into disjoint regions. These regions are related by permutation symmetry, hence they are fully degenerate with respect to their entropies and statistical properties. This prediction has been tested by simulations of the K=3 case, calculating the order parameters by random walks in the space of solutions. They yield good evidence for existence of a phase with broken permutation symmetry at values of α>=2. Finally, both theory and simulations show that for a typical fully connected network the connections joining the same input to a pair of hidden units are negatively correlated.
Strongly broken Peccei-Quinn symmetry in the early Universe
Takahashi, Fuminobu; Yamada, Masaki E-mail: yamadam@icrr.u-tokyo.ac.jp
2015-10-01
We consider QCD axion models where the Peccei-Quinn symmetry is badly broken by a larger amount in the past than in the present, in order to avoid the axion isocurvature problem. Specifically we study supersymmetric axion models where the Peccei-Quinn symmetry is dynamically broken by either hidden gauge interactions or the SU(3){sub c} strong interactions whose dynamical scales are temporarily enhanced by the dynamics of flat directions. The former scenario predicts a large amount of self-interacting dark radiation as the hidden gauge symmetry is weakly coupled in the present Universe. We also show that the observed amount of baryon asymmetry can be generated by the QCD axion dynamics via spontaneous baryogenesis. We briefly comment on the case in which the PQ symmetry is broken by a non-minimal coupling to gravity.
Strongly broken Peccei-Quinn symmetry in the early Universe
Takahashi, Fuminobu; Yamada, Masaki
2015-10-06
We consider QCD axion models where the Peccei-Quinn symmetry is badly broken by a larger amount in the past than in the present, in order to avoid the axion isocurvature problem. Specifically we study supersymmetric axion models where the Peccei-Quinn symmetry is dynamically broken by either hidden gauge interactions or the SU(3){sub c} strong interactions whose dynamical scales are temporarily enhanced by the dynamics of flat directions. The former scenario predicts a large amount of self-interacting dark radiation as the hidden gauge symmetry is weakly coupled in the present Universe. We also show that the observed amount of baryon asymmetry can be generated by the QCD axion dynamics via spontaneous baryogenesis. We briefly comment on the case in which the PQ symmetry is broken by a non-minimal coupling to gravity.
Strongly broken Peccei-Quinn symmetry in the early Universe
NASA Astrophysics Data System (ADS)
Takahashi, Fuminobu; Yamada, Masaki
2015-10-01
We consider QCD axion models where the Peccei-Quinn symmetry is badly broken by a larger amount in the past than in the present, in order to avoid the axion isocurvature problem. Specifically we study supersymmetric axion models where the Peccei-Quinn symmetry is dynamically broken by either hidden gauge interactions or the SU(3)c strong interactions whose dynamical scales are temporarily enhanced by the dynamics of flat directions. The former scenario predicts a large amount of self-interacting dark radiation as the hidden gauge symmetry is weakly coupled in the present Universe. We also show that the observed amount of baryon asymmetry can be generated by the QCD axion dynamics via spontaneous baryogenesis. We briefly comment on the case in which the PQ symmetry is broken by a non-minimal coupling to gravity.
Spontaneously broken spacetime symmetries and Goldstone's theorem.
Low, Ian; Manohar, Aneesh V
2002-03-11
Goldstone's theorem states that there is a massless mode for each broken symmetry generator. It has been known for a long time that the naive generalization of this counting fails to give the correct number of massless modes for spontaneously broken spacetime symmetries. We explain how to get the right count of massless modes in the general case, and discuss examples involving spontaneously broken Poincaré and conformal invariance.
Kastner, Ruth E.
2011-11-29
This paper seeks to clarify features of time asymmetry in terms of symmetry breaking. It is observed that, in general, a contingent situation or event requires the breaking of an underlying symmetry. The distinction between the universal anisotropy of temporal processes and the irreversibility of certain physical processes is clarified. It is also proposed that the Transactional Interpretation of quantum mechanics offers an effective way to explain general thermodynamic asymmetry in terms of the time asymmetry of radiation, where prior such efforts have fallen short.
Broken symmetry in ideal magnetohydrodynamic turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
1993-01-01
A numerical study of the long-time evolution of a number of cases of inviscid, isotropic, incompressible, three-dimensional fluid, and magneto-fluid turbulence has been completed. The results confirm that ideal magnetohydrodynamic turbulence is non-ergodic if there is no external magnetic field present. This is due essentially to a canonical symmetry being broken in an arbitrary dynamical representation. The broken symmetry manifests itself as a coherent structure, i.e., a non-zero time-averaged part of the turbulent magnetic field. The coherent structure is observed, in one case, to contain about eighteen percent of the total energy.
From physical symmetries to emergent gauge symmetries
NASA Astrophysics Data System (ADS)
Barceló, Carlos; Carballo-Rubio, Raúl; Di Filippo, Francesco; Garay, Luis J.
2016-10-01
Gauge symmetries indicate redundancies in the description of the relevant degrees of freedom of a given field theory and restrict the nature of observable quantities. One of the problems faced by emergent theories of relativistic fields is to understand how gauge symmetries can show up in systems that contain no trace of these symmetries at a more fundamental level. In this paper we start a systematic study aimed to establish a satisfactory mathematical and physical picture of this issue, dealing first with abelian field theories. We discuss how the trivialization, due to the decoupling and lack of excitation of some degrees of freedom, of the Noether currents associated with physical symmetries leads to emergent gauge symmetries in specific situations. An example of a relativistic field theory of a vector field is worked out in detail in order to make explicit how this mechanism works and to clarify the physics behind it. The interplay of these ideas with well-known results of importance to the emergent gravity program, such as the Weinberg-Witten theorem, are discussed.
NASA Astrophysics Data System (ADS)
Greschner, S.; Piraud, M.; Heidrich-Meisner, F.; McCulloch, I. P.; Schollwöck, U.; Vekua, T.
2016-12-01
We study the quantum phases of bosons with repulsive contact interactions on a two-leg ladder in the presence of a uniform Abelian gauge field. The model realizes many interesting states, including Meissner phases, vortex fluids, vortex lattices, charge density waves, and the biased-ladder phase. Our work focuses on the subset of these states that breaks a discrete symmetry. We use density matrix renormalization group simulations to demonstrate the existence of three vortex-lattice states at different vortex densities and we characterize the phase transitions from these phases into neighboring states. Furthermore, we provide an intuitive explanation of the chiral-current reversal effect that is tied to some of these vortex lattices. We also study a charge-density-wave state that exists at 1/4 particle filling at large interaction strengths and flux values close to half a flux quantum. By changing the system parameters, this state can transition into a completely gapped vortex-lattice Mott-insulating state. We elucidate the stability of these phases against nearest-neighbor interactions on the rungs of the ladder relevant for experimental realizations with a synthetic lattice dimension. A charge-density-wave state at 1/3 particle filling can be stabilized for flux values close to half a flux quantum and for very strong on-site interactions in the presence of strong repulsion on the rungs. Finally, we analytically describe the emergence of these phases in the low-density regime, and, in particular, we obtain the boundaries of the biased-ladder phase, i.e., the phase that features a density imbalance between the legs. We make contact with recent quantum-gas experiments that realized related models and discuss signatures of these quantum states in experimentally accessible observables.
Dark matter and gauged flavor symmetries
Bishara, Fady; Greljo, Admir; Kamenik, Jernej F.; ...
2015-12-21
We investigate the phenomenology of flavored dark matter (DM). DM stability is guaranteed by an accidental Z3 symmetry, a subgroup of the standard model (SM) flavor group that is not broken by the SM Yukawa interactions. We consider an explicit realization where the quark part of the SM flavor group is fully gauged. If the dominant interactions between DM and visible sector are through flavor gauge bosons, as we show for Dirac fermion flavored DM, then the DM mass is bounded between roughly 0.5 TeV and 5 TeV if the DM multiplet mass is split only radiatively. In general, however,more » no such relation exists. We demonstrate this using scalar flavored DM where the main interaction with the SM is through the Higgs portal. For both cases we derive constraints from flavor, cosmology, direct and indirect DM detection, and collider searches.« less
Dark matter and gauged flavor symmetries
Bishara, Fady; Greljo, Admir; Kamenik, Jernej F.; Stamou, Emmanuel; Zupan, Jure
2015-12-21
We investigate the phenomenology of flavored dark matter (DM). DM stability is guaranteed by an accidental Z_{3} symmetry, a subgroup of the standard model (SM) flavor group that is not broken by the SM Yukawa interactions. We consider an explicit realization where the quark part of the SM flavor group is fully gauged. If the dominant interactions between DM and visible sector are through flavor gauge bosons, as we show for Dirac fermion flavored DM, then the DM mass is bounded between roughly 0.5 TeV and 5 TeV if the DM multiplet mass is split only radiatively. In general, however, no such relation exists. We demonstrate this using scalar flavored DM where the main interaction with the SM is through the Higgs portal. For both cases we derive constraints from flavor, cosmology, direct and indirect DM detection, and collider searches.
Nonreciprocal Multiferroic Superlattices with Broken Parity Symmetry
NASA Astrophysics Data System (ADS)
Tang, Zhenghua; Zhang, Weiyi
Multiferroic materials are characterized by the coexistence of ferroelectric and ferromagnetic (or antiferromagnetic) orders, the coupling to lattice vibration can be invoked either through piezoelectric or piezomagnetic effects. In this paper, the polaritonic band structures of multiferroic superlattices composed of oppositely polarized domains are investigated using the generalized transfer matrix method. For the primitive cell with broken parity symmetry, the polaritonic band structure is asymmetrical with respect to the forward and backward propagation directions (nonreciprocality). In particular, the band extreme points move away from the Brillouin zone center. This asymmetry in band-gap positions and widths can be used to design compact one-way optical isolators, while the extremely slow light velocities near the asymmetrical upper edges of lower bands includes the essential ingredients for designing slow light devices.
Entanglement entropy in quantum spin chains with broken reflection symmetry
Kadar, Zoltan; Zimboras, Zoltan
2010-09-15
We investigate the entanglement entropy of a block of L sites in quasifree translation-invariant spin chains concentrating on the effect of reflection-symmetry breaking. The Majorana two-point functions corresponding to the Jordan-Wigner transformed fermionic modes are determined in the most general case; from these, it follows that reflection symmetry in the ground state can only be broken if the model is quantum critical. The large L asymptotics of the entropy are calculated analytically for general gauge-invariant models, which have, until now, been done only for the reflection-symmetric sector. Analytical results are also derived for certain nongauge-invariant models (e.g., for the Ising model with Dzyaloshinskii-Moriya interaction). We also study numerically finite chains of length N with a nonreflection-symmetric Hamiltonian and report that the reflection symmetry of the entropy of the first L spins is violated but the reflection-symmetric Calabrese-Cardy formula is recovered asymptotically. Furthermore, for noncritical reflection-symmetry-breaking Hamiltonians, we find an anomaly in the behavior of the saturation entropy as we approach the critical line. The paper also provides a concise but extensive review of the block-entropy asymptotics in translation-invariant quasifree spin chains with an analysis of the nearest-neighbor case and the enumeration of the yet unsolved parts of the quasifree landscape.
A nilpotent symmetry of quantum gauge theories
NASA Astrophysics Data System (ADS)
Lahiri, Amitabha
2001-09-01
For the Becchi-Rouet-Stora-Tyutin invariant extended action for any gauge theory, there exists another off-shell nilpotent symmetry. For linear gauges, it can be elevated to a symmetry of the quantum theory and used in the construction of the quantum effective action. Generalizations for nonlinear gauges and actions with higher-order ghost terms are also possible.
Neutrino Mixing:. from the Broken μ-τ Symmetry to the Broken Friedberg-Lee Symmetry
NASA Astrophysics Data System (ADS)
Xing, Zhi-Zhong
I argue that the observed flavor structures of leptons and quarks might imply the existence of certain flavor symmetries. The latter should be a good starting point to build realistic models towards deeper understanding of the fermion mass spectra and flavor mixing patterns. The μ-τ permutation symmetry serves for such an example to interpret the almost maximal atmospheric neutrino mixing angle (θ23 ~ 45°) and the strongly suppressed CHOOZ neutrino mixing angle (θ13 < 10°). In this talk I like to highlight a new kind of flavor symmetry, the Friedberg-Lee symmetry, for the effective Majorana neutrino mass operator. Luo and I have shown that this symmetry can be broken in an oblique way, such that the lightest neutrino remains massless but an experimentally-favored neutrino mixing pattern is achievable. We get a novel prediction for θ13 in the CP-conserving case: sinθ13 = tanθ12|(1 - tanθ23)/(1 + tanθ23)|. Our scenario can simply be generalized to accommodate CP violation and be combined with the seesaw mechanism. Finally I stress the importance of probing possible effects of μ-τ symmetry breaking either in terrestrial neutrino oscillation experiments or with ultrahigh-energy cosmic neutrino telescopes.
On Gauging Symmetry of Modular Categories
NASA Astrophysics Data System (ADS)
Cui, Shawn X.; Galindo, César; Plavnik, Julia Yael; Wang, Zhenghan
2016-12-01
Topological order of a topological phase of matter in two spacial dimensions is encoded by a unitary modular (tensor) category (UMC). A group symmetry of the topological phase induces a group symmetry of its corresponding UMC. Gauging is a well-known theoretical tool to promote a global symmetry to a local gauge symmetry. We give a mathematical formulation of gauging in terms of higher category formalism. Roughly, given a UMC with a symmetry group G, gauging is a 2-step process: first extend the UMC to a G-crossed braided fusion category and then take the equivariantization of the resulting category. Gauging can tell whether or not two enriched topological phases of matter are different, and also provides a way to construct new UMCs out of old ones. We derive a formula for the {H^4}-obstruction, prove some properties of gauging, and carry out gauging for two concrete examples.
Gauged twistor spinors and symmetry operators
NASA Astrophysics Data System (ADS)
Ertem, Ümit
2017-03-01
We consider gauged twistor spinors which are supersymmetry generators of supersymmetric and superconformal field theories in curved backgrounds. We show that the spinor bilinears of gauged twistor spinors satisfy the gauged conformal Killing-Yano equation. We prove that the symmetry operators of the gauged twistor spinor equation can be constructed from ordinary conformal Killing-Yano forms in constant curvature backgrounds. This provides a way to obtain gauged twistor spinors from ordinary twistor spinors.
Casimir effect for regions with broken symmetry of boundaries
Zayaev, Yu.B.; Kazakov, A.Ya.; Mostepanenko, V.M.; Trunov, N.N.
1989-01-01
A method is proposed for computing corrections to the Casimir force caused by a broken symmetry of the boundaries. The values of these corrections are obtained for a parallelepiped in the case of scalar and electromagnetic fields.
The role of gauge symmetry in spintronics
Sobreiro, R.F.
2011-12-15
In this work we employ a field theoretical approach to explain the nature of the non-conserved spin current in spintronics. In particular, we consider the usual U(1) gauge theory for the electromagnetism at classical level in order to obtain the broken continuity equation involving the spin current and spin-transfer torque. Inspired by the recent work of A. Vernes, B. L. Gyorffy and P. Weinberger where they obtain such an equation in terms of relativistic quantum mechanics, we formalize their result in terms of the well known currents of field theory such as the Bargmann-Wigner current and the chiral current. Thus, an interpretation of spintronics is provided in terms of Noether currents (conserved or not) and symmetries of the electromagnetism. In fact, the main result of the present work is that the non-conservation of the spin current is associated with the gauge invariance of physical observables where the breaking term is proportional to the chiral current. Moreover, we generalize their result by including the electromagnetic field as a dynamical field instead of an external one.
Discrete gauge symmetry in continuum theories
Krauss, L.M.; Wilczek, F.
1989-03-13
We point out that local symmetries can masquerade as discrete global symmetries to an observer equipped with only low-energy probes. The existence of the underlying local gauge invariance can, however, result in observable Aharonov-Bohm-type effects. Black holes can therefore carry discrete gauge charges: a form of nonclassical ''hair.'' Neither black-hole evaporation, wormholes, nor anything else can violate discrete gauge symmetries. In supersymmetric unified theories such discrete symmetries can forbid proton-decay amplitudes that might otherwise be catastrophic.
BRST symmetry in the general gauge theories
NASA Astrophysics Data System (ADS)
Hyuk-Jae, Lee; Jae, Hyung, Yee
1994-01-01
By using the residual gauge symmetry interpretation of BRST invariance we have constructed a new BRST formulation for general gauge theories including those with open algebras. For theories with open gauge algebra the formulation leads to a BRST invariant effective action which does not contain any higher order terms in the ghost fields.
Broken chiral symmetry on a null plane
Beane, Silas R.
2013-10-15
On a null-plane (light-front), all effects of spontaneous chiral symmetry breaking are contained in the three Hamiltonians (dynamical Poincaré generators), while the vacuum state is a chiral invariant. This property is used to give a general proof of Goldstone’s theorem on a null-plane. Focusing on null-plane QCD with N degenerate flavors of light quarks, the chiral-symmetry breaking Hamiltonians are obtained, and the role of vacuum condensates is clarified. In particular, the null-plane Gell-Mann–Oakes–Renner formula is derived, and a general prescription is given for mapping all chiral-symmetry breaking QCD condensates to chiral-symmetry conserving null-plane QCD condensates. The utility of the null-plane description lies in the operator algebra that mixes the null-plane Hamiltonians and the chiral symmetry charges. It is demonstrated that in a certain non-trivial limit, the null-plane operator algebra reduces to the symmetry group SU(2N) of the constituent quark model. -- Highlights: •A proof (the first) of Goldstone’s theorem on a null-plane is given. •The puzzle of chiral-symmetry breaking condensates on a null-plane is solved. •The emergence of spin-flavor symmetries in null-plane QCD is demonstrated.
Symmetry-broken states on networks of coupled oscillators
NASA Astrophysics Data System (ADS)
Jiang, Xin; Abrams, Daniel M.
2016-05-01
When identical oscillators are coupled together in a network, dynamical steady states are often assumed to reflect network symmetries. Here, we show that alternative persistent states may also exist that break the symmetries of the underlying coupling network. We further show that these symmetry-broken coexistent states are analogous to those dubbed "chimera states," which can occur when identical oscillators are coupled to one another in identical ways.
Broken SU(3) x SU(3) x SU(3) x SU(3) Symmetry
DOE R&D Accomplishments Database
Freund, P. G. O.; Nambu, Y.
1964-10-01
We argue that the "Eight-fold Way" version of the SU(3) symmetry should be extended to a product of up to four separate and badly broken SU(3) groups, including the gamma{sub 5} type SU(3) symmetry. A hierarchy of subgroups (or subalgebras) are considered within this framework, and two candidates are found to be interesting in view of experimental evidence. Main features of the theory are: 1) the baryons belong to a nonet; 2) there is an octet of axial vector gauge mesons in addition to one or two octets of vector mesons; 3) pseudoscalar and scalar mesons exist as "incomplete" multiplets arising from spontaneous breakdown of symmetry.
Dynamical Symmetry Breaking of Extended Gauge Symmetries
NASA Astrophysics Data System (ADS)
Appelquist, Thomas; Shrock, Robert
2003-05-01
We construct asymptotically free gauge theories exhibiting dynamical breaking of the left-right gauge group GLR=SU(3)c×SU(2)L×SU(2)R×U(1)B-L, and its extension to the Pati-Salam gauge group G422=SU(4)PS×SU(2)L×SU(2)R. The models incorporate technicolor for electroweak breaking, and extended technicolor for the breaking of GLR and G422 and the generation of fermion masses. They include a seesaw mechanism for neutrino masses, without a grand unified theory (GUT) scale. These models explain why GLR and G422 break to SU(3)c×SU(2)L×U(1)Y, and why this takes place at a scale (˜103 TeV) large compared to the electroweak scale, but much smaller than a GUT scale.
Broken-Symmetry Quantum Hall States in Twisted Bilayer Graphene
Kim, Youngwook; Park, Jaesung; Song, Intek; Ok, Jong Mok; Jo, Younjung; Watanabe, Kenji; Taniquchi, Takashi; Choi, Hee Cheul; Lee, Dong Su; Jung, Suyong; Kim, Jun Sung
2016-01-01
Twisted bilayer graphene offers a unique bilayer two-dimensional-electron system where the layer separation is only in sub-nanometer scale. Unlike Bernal-stacked bilayer, the layer degree of freedom is disentangled from spin and valley, providing eight-fold degeneracy in the low energy states. We have investigated broken-symmetry quantum Hall (QH) states and their transitions due to the interplay of the relative strength of valley, spin and layer polarizations in twisted bilayer graphene. The energy gaps of the broken-symmetry QH states show an electron-hole asymmetric behaviour, and their dependence on the induced displacement field are opposite between even and odd filling factor states. These results strongly suggest that the QH states with broken valley and spin symmetries for individual layer become hybridized via interlayer tunnelling, and the hierarchy of the QH states is sensitive to both magnetic field and displacement field due to charge imbalance between layers. PMID:27905496
Broken-Symmetry Quantum Hall States in Twisted Bilayer Graphene
NASA Astrophysics Data System (ADS)
Kim, Youngwook; Park, Jaesung; Song, Intek; Ok, Jong Mok; Jo, Younjung; Watanabe, Kenji; Taniquchi, Takashi; Choi, Hee Cheul; Lee, Dong Su; Jung, Suyong; Kim, Jun Sung
2016-12-01
Twisted bilayer graphene offers a unique bilayer two-dimensional-electron system where the layer separation is only in sub-nanometer scale. Unlike Bernal-stacked bilayer, the layer degree of freedom is disentangled from spin and valley, providing eight-fold degeneracy in the low energy states. We have investigated broken-symmetry quantum Hall (QH) states and their transitions due to the interplay of the relative strength of valley, spin and layer polarizations in twisted bilayer graphene. The energy gaps of the broken-symmetry QH states show an electron-hole asymmetric behaviour, and their dependence on the induced displacement field are opposite between even and odd filling factor states. These results strongly suggest that the QH states with broken valley and spin symmetries for individual layer become hybridized via interlayer tunnelling, and the hierarchy of the QH states is sensitive to both magnetic field and displacement field due to charge imbalance between layers.
Unification mechanism for gauge and spacetime symmetries
NASA Astrophysics Data System (ADS)
László, András
2017-03-01
A group theoretical mechanism for unification of local gauge and spacetime symmetries is introduced. No-go theorems prohibiting such unification are circumvented by slightly relaxing the usual requirement on the gauge group: only the so called Levi factor of the gauge group needs to be compact semisimple, not the entire gauge group. This allows a non-conventional supersymmetry-like extension of the gauge group, glueing together the gauge and spacetime symmetries, but not needing any new exotic gauge particles. It is shown that this new relaxed requirement on the gauge group is nothing but the minimal condition for energy positivity. The mechanism is demonstrated to be mathematically possible and physically plausible on a \\text{U}(1) based gauge theory setting. The unified group, being an extension of the group of spacetime symmetries, is shown to be different than that of the conventional supersymmetry group, thus overcoming the McGlinn and Coleman–Mandula no-go theorems in a non-supersymmetric way.
Elastoconductivity as a probe of broken mirror symmetries
Hlobil, Patrik; Maharaj, Akash V.; Hosur, Pavan; Shapiro, M. C.; Fisher, I. R.; Raghu, S.
2015-07-27
We propose the possible detection of broken mirror symmetries in correlated two-dimensional materials by elastotransport measurements. Using linear response theory we calculate the“shear conductivity” Γ x x , x y , defined as the linear change of the longitudinal conductivity σ x x due to a shear strain ε x y . This quantity can only be nonvanishing when in-plane mirror symmetries are broken and we discuss how candidate states in the cuprate pseudogap regime (e.g., various loop current or charge orders) may exhibit a finite shear conductivity. We also provide a realistic experimental protocol for detecting such a response.
Radiatively broken symmetries of nonhierarchical neutrinos
NASA Astrophysics Data System (ADS)
Dighe, Amol; Goswami, Srubabati; Roy, Probir
2007-11-01
Symmetry-based ideas, such as the quark-lepton complementarity principle and the tribimaximal mixing scheme, have been proposed to explain the observed mixing pattern of neutrinos. We argue that such symmetry relations need to be imposed at a high scale Λ˜1012GeV characterizing the large masses of right-handed neutrinos required to implement the seesaw mechanism. For nonhierarchical neutrinos, renormalization group evolution down to a laboratory energy scale λ˜103GeV tends to radiatively break these symmetries at a significant level and spoil the mixing pattern predicted by them. However, for Majorana neutrinos, suitable constraints on the extra phases α2,3 enable the retention of those high scale mixing patterns at laboratory energies. We examine this issue within the minimal supersymmetric standard model and demonstrate the fact posited above for two versions of quark-lepton complementarity and two versions of tribimaximal mixing. The appropriate constraints are worked out for all these four cases. Specifically, a preference for α2≈π (i.e., m1≈-m2) emerges in each case. We also show how a future accurate measurement of θ13 may enable some discrimination among these four cases in spite of renormalization group evolution.
Non-gaussianity from broken symmetries
Kolb, Edward W.; Riotto, Antonio; Vallinotto, Alberto; /Chicago U. /Fermilab
2005-11-01
Recently we studied inflation models in which the inflation potential is characterized by an underlying approximate global symmetry. In the first work we pointed out that in such a model curvature perturbations are generated after the end of the slow-roll phase of inflation. In this work we develop further the observational implications of the model and compute the degree of non-Gaussianity predicted in the scenario. We find that the corresponding nonlinearity parameter, F{sub NL}, can be as large as 10{sup 2}.
Detecting broken \\mathbf{\\mathsf{PT}} -symmetry
NASA Astrophysics Data System (ADS)
Weigert, Stefan
2006-08-01
A fundamental problem in the theory of \\mathbf{\\mathsf{PT}} -invariant quantum systems is to determine whether a given system 'respects' this symmetry or not. If not, the system usually develops non-real eigenvalues. It is shown in this contribution how to algorithmically detect the existence of complex eigenvalues for a given PT-symmetric matrix. The procedure uses classical results from stability theory which qualitatively locate the zeros of real polynomials in the complex plane. The interest and value of the present approach lies in the fact that it avoids diagonalization of the Hamiltonian at hand.
Unity of quark and lepton interactions with symplectic gauge symmetry
Rajpoot, S.
1982-07-01
Properties of symplectic groups are reviewed and the gauge structure of Sp(2n) derived. The electroweak unification of leptons within Sp(8) gauge symmetry and grand unification of quarks and leptons within Sp(10) gauge symmetry are discussed.
Early ERA in a broken-symmetry theory of gravity
NASA Astrophysics Data System (ADS)
Krori, K. D.; Chaudhury, T.; Mahanta, Chandra R.
1992-12-01
We discuss in this paper the early era of Robertson-Walker, Kantowski-Sachs, and Bianchi type I cosmologies in the light of a broken-symmetry theory of gravity proposed by Chandra. The conclusions for all three cosmologies are briefly presented for comparison. Some results of Chandra's calculation on Robertson-Walker cosmology are corrected.
Beyond the standard gauging: gauge symmetries of Dirac sigma models
NASA Astrophysics Data System (ADS)
Chatzistavrakidis, Athanasios; Deser, Andreas; Jonke, Larisa; Strobl, Thomas
2016-08-01
In this paper we study the general conditions that have to be met for a gauged extension of a two-dimensional bosonic σ-model to exist. In an inversion of the usual approach of identifying a global symmetry and then promoting it to a local one, we focus directly on the gauge symmetries of the theory. This allows for action functionals which are gauge invariant for rather general background fields in the sense that their invariance conditions are milder than the usual case. In particular, the vector fields that control the gauging need not be Killing. The relaxation of isometry for the background fields is controlled by two connections on a Lie algebroid L in which the gauge fields take values, in a generalization of the common Lie-algebraic picture. Here we show that these connections can always be determined when L is a Dirac structure in the H-twisted Courant algebroid. This also leads us to a derivation of the general form for the gauge symmetries of a wide class of two-dimensional topological field theories called Dirac σ-models, which interpolate between the G/G Wess-Zumino-Witten model and the (Wess-Zumino-term twisted) Poisson sigma model.
Large gauge symmetries and asymptotic states in QED
NASA Astrophysics Data System (ADS)
Gabai, Barak; Sever, Amit
2016-12-01
Large Gauge Transformations (LGT) are gauge transformations that do not vanish at infinity. Instead, they asymptotically approach arbitrary functions on the conformal sphere at infinity. Recently, it was argued that the LGT should be treated as an infinite set of global symmetries which are spontaneously broken by the vacuum. It was established that in QED, the Ward identities of their induced symmetries are equivalent to the Soft Photon Theorem. In this paper we study the implications of LGT on the S-matrix between physical asymptotic states in massive QED. In appose to the naively free scattering states, physical asymptotic states incorporate the long range electric field between asymptotic charged particles and were already constructed in 1970 by Kulish and Faddeev. We find that the LGT charge is independent of the particles' momenta and may be associated to the vacuum. The soft theorem's manifestation as a Ward identity turns out to be an outcome of not working with the physical asymptotic states.
Consistency condition for inflation from (broken) conformal symmetry
Schalm, Koenraad; Aalst, Ted van der; Shiu, Gary E-mail: shiu@physics.wisc.edu
2013-03-01
We investigate the symmetry constraints on the bispectrum, i.e. the three-point correlation function of primordial density fluctuations, in slow-roll inflation. It follows from the defining property of slow-roll inflation that primordial correlation functions inherit most of their structure from weakly broken de Sitter symmetries. Using holographic techniques borrowed from the AdS/CFT correspondence, the symmetry constraints on the bispectrum can be mapped to a set of stress-tensor Ward identities in a weakly broken 2+1-dimensional Euclidean CFT. We construct the consistency condition from these Ward identities using conformal perturbation theory. This requires a second order Ward identity and the use of the evolution equation. Our result also illustrates a subtle difference between conformal perturbation theory and the slow-roll expansion.
Topological aspects of systems with broken time-reversal symmetry
NASA Astrophysics Data System (ADS)
Raghu, Srinivas
This thesis deals with two topics involving topological "vortex-like" defects arising due to the breaking of time-reversal symmetry. A recurring theme shall be the interplay between the bulk properties and the physics at the boundaries of such systems. In the first part of the thesis, we construct direct analogs of quantum Hall effect edge modes in photonic systems with broken time-reversal symmetry. We will show how "photonic crystals" built out of time-reversal breaking Faraday effect media can exhibit "chiral" edge modes in which light propagates unidirectionally along boundaries across which the Faraday axis reverses. The crucial feature underlying this idea is that the photon bands of interest have non-zero Chern numbers (topological integers, which in the case at hand, represent the winding number of the Berry gauge connection of the bands). Using both numerical diagonalization and simple analytical models, we show how to construct photon bands with non-zero Chern invariants, and we use them to realize the precise classical counterpart of the electronic edge modes of the quantum Hall effect. To study these modes numerically, we have designed and implemented novel real-space treatments of the source-free Maxwell normal mode problem on a discrete network. In the second part of the thesis, we focus on extreme type II superconductors in externally applied magnetic fields. Motivated by experiments of Ong and collaborators on the Nernst effect in the cuprate superconductors, we consider a model of a superconductor which permits fluctuations only in the phase of the order parameter. In the presence of the magnetic field, a net vorticity is induced in the system, and we consider the various static and thermoelectric signatures of these superconducting vortices. Using numerical simulations, analytical calculations, and arguments from duality, we study thermoelectric transport and boundary diamagnetic currents. We conclude that such simple models of superconductors
Gauge Transformations as Spacetime Symmetries
Angeles, Rene; Napsuciale, Mauro
2009-04-20
Weinberg has shown that massless fields of helicity {+-}1(vector fields) do not transform homogeneously under Unitary Lorentz Transformations (LT). We calculate explicitly the inhomogeneous term. We show that imposing strict invariance of the Lagrangian under LT for an iteracting Dirac field requires the fermion field to transform with a space-time (and photon creation and annihilation operators) dependent phase and dictates the interaction terms as those arising from the conventional gauge principle.
Adiabatic approximation for the Rabi model with broken inversion symmetry
NASA Astrophysics Data System (ADS)
Shen, Li-Tuo; Yang, Zhen-Biao; Wu, Huai-Zhi
2017-01-01
We study the properties and behavior of the Rabi model with broken inversion symmetry. Using an adiabatic approximation approach, we explore the high-frequency qubit and oscillator regimes, and obtain analytical solutions for the qubit-oscillator system. We demonstrate that, due to broken inversion symmetry, the positions of two potentials and zero-point energies in the oscillators become asymmetric and have a quadratic dependence on the mean dipole moments within the high-frequency oscillator regime. Furthermore, we find that there is a critical point above which the qubit-oscillator system becomes unstable, and the position of this critical point has a quadratic dependence on the mean dipole moments within the high-frequency qubit regime. Finally, we verify this critical point based on the method of semiclassical approximation.
Approximate gauge symmetry of composite vector bosons
NASA Astrophysics Data System (ADS)
Suzuki, Mahiko
2010-08-01
It can be shown in a solvable field theory model that the couplings of the composite vector bosons made of a fermion pair approach the gauge couplings in the limit of strong binding. Although this phenomenon may appear accidental and special to the vector bosons made of a fermion pair, we extend it to the case of bosons being constituents and find that the same phenomenon occurs in a more intriguing way. The functional formalism not only facilitates computation but also provides us with a better insight into the generating mechanism of approximate gauge symmetry, in particular, how the strong binding and global current conservation conspire to generate such an approximate symmetry. Remarks are made on its possible relevance or irrelevance to electroweak and higher symmetries.
The Corolla Polynomial for Spontaneously Broken Gauge Theories
NASA Astrophysics Data System (ADS)
Prinz, David
2016-09-01
In Kreimer and Yeats (Electr. J. Comb. 41-41, 2013), Kreimer et al. (Annals Phys. 336, 180-222, 2013) and Sars (2015) the Corolla Polynomial C ({Γ }) in C [a_{h1}, ldots , a_{h_{ \\vert {Γ }^{[1/2]} \\vert }}] was introduced as a graph polynomial in half-edge variables {ah}_{h in {Γ }^{[1/2]}} over a 3-regular scalar quantum field theory (QFT) Feynman graph Γ. It allows for a covariant quantization of pure Yang-Mills theory without the need for introducing ghost fields, clarifies the relation between quantum gauge theory and scalar QFT with cubic interaction and translates back the problem of renormalizing quantum gauge theory to the problem of renormalizing scalar QFT with cubic interaction (which is super renormalizable in 4 dimensions of spacetime). Furthermore, it is, as we believe, useful for computer calculations. In Prinz (2015) on which this paper is based the formulation of Kreimer and Yeats (Electr. J. Comb. 41-41, 2013), Kreimer et al. (Annals Phys. 336, 180-222, 2013) and Sars (2015) gets slightly altered in a fashion specialized in the case of the Feynman gauge. It is then formulated as a graph polynomial C ({Γ } ) in C [a_{h_{1 ± }}, ldots , a_{h_{ \\vert {Γ }^{[1/2]} \\vert } {h}_{± }}, b_{h1}, ldots , b_{h_{ \\vert {Γ }^{[1/2]} \\vert }}] in three different types of half-edge variables {a_{h+} , a_{h-} , bh}_{h in {Γ }^{[1/2]}} . This formulation is also suitable for the generalization to the case of spontaneously broken gauge theories (in particular all bosons from the Standard Model), as was first worked out in Prinz (2015) and gets reviewed here.
Whispering gallery resonators with broken axial symmetry: Theory and experiment.
Fürst, J; Sturman, B; Buse, K; Breunig, I
2016-09-05
Axial symmetry is the cornerstone for theory and applications of high-Q optical whispering gallery resonators (WGRs). Nevertheless, research on birefringent crystalline material persistently pushes towards breaking this symmetry. We show theoretically and experimentally that the effect of broken axial symmetry, caused by optical anisotropy, is modest for the resonant frequencies and Q-factors of the WGR modes. Thus, the most important equatorial whispering gallery modes can be quantitatively described and experimentally identified. At the same time, the effect of broken axial symmetry on the light field distribution of the whispering gallery modes is typically very strong. This qualitatively modifies the phase-matching for the χ^{(2)} nonlinear processes and enables broad-band second harmonic generation and optical parametric oscillation. The effect of weak geometric ellipticity in nominally symmetric WGRs is also considered. Altogether our findings pave the way for an extensive use of numerous birefringent (uniaxial and biaxial) crystals with broad transparency window and large χ^{(2)} coefficients in nonlinear optics with WGRs.
SU(3) family gauge symmetry and the axion
Appelquist, Thomas; Bai Yang; Piai, Maurizio
2007-04-01
We analyze the structure of a recently proposed effective field theory (EFT) for the generation of quark and lepton mass ratios and mixing angles, based on the spontaneous breaking of an SU(3) family gauge symmetry at a high scale F. We classify the Yukawa operators necessary to seed the masses, making use of the continuous global symmetries that they preserve. One global U(1), in addition to baryon number and electroweak hypercharge, remains unbroken after the inclusion of all operators required by standard model fermion phenomenology. An associated vacuum symmetry insures the vanishing of the first-family quark and charged-lepton masses in the absence of the family gauge interaction. If this U(1) symmetry is taken to be exact in the EFT, broken explicitly by only the QCD-induced anomaly, and if the breaking scale F is taken to lie in the range 10{sup 9}-10{sup 12} GeV, then the associated Nambu-Goldstone boson is a potential QCD axion.
Entanglement entropy and nonabelian gauge symmetry
NASA Astrophysics Data System (ADS)
Donnelly, William
2014-11-01
Entanglement entropy has proven to be an extremely useful concept in quantum field theory. Gauge theories are of particular interest, but for these systems the entanglement entropy is not clearly defined because the physical Hilbert space does not factor as a tensor product according to regions of space. Here we review a definition of entanglement entropy that applies to abelian and nonabelian lattice gauge theories. This entanglement entropy is obtained by embedding the physical Hilbert space into a product of Hilbert spaces associated to regions with boundary. The latter Hilbert spaces include degrees of freedom on the entangling surface that transform like surface charges under the gauge symmetry. These degrees of freedom are shown to contribute to the entanglement entropy, and the form of this contribution is determined by the gauge symmetry. We test our definition using the example of two-dimensional Yang-Mills theory, and find that it agrees with the thermal entropy in de Sitter space, and with the results of the Euclidean replica trick. We discuss the possible implications of this result for more complicated gauge theories, including quantum gravity.
Superheavy dark matter with discrete gauge symmetries
NASA Astrophysics Data System (ADS)
Hamaguchi, K.; Nomura, Yasunori; Yanagida, T.
1998-11-01
We show that there are discrete gauge symmetries which naturally protect heavy X particles from decaying into ordinary light particles in the supersymmetric standard model. This makes the proposal that superheavy X particles constitute part of the dark matter in the present universe very attractive. It is more interesting that there is a class of discrete gauge symmetries which naturally accommodates a long-lived unstable X particle. We find that in some discrete Z10 models, for example, a superheavy X particle has a lifetime of τX~=1011-1026 yr for a mass of MX~=1013-1014 GeV. This long lifetime is guaranteed by the absence of lower dimensional operators (of light particles) coupled to the X. We briefly discuss a possible explanation for the recently observed ultrahigh-energy cosmic ray events by the decay of this unstable X particle.
Cosmology of a universe with spontaneously broken Lorentz symmetry
Ferreira, P. G.; Gripaios, B. M.; Zlosnik, T. G.; Saffari, R.
2007-02-15
A self-consistent effective field theory of modified gravity has recently been proposed with spontaneous breaking of local Lorentz invariance. The symmetry is broken by a vector field with the wrong-sign mass term and it has been shown to have additional graviton modes and modified dispersion relations. In this paper we study the evolution of a homogeneous and isotropic universe in the presence of such a vector field with a minimum lying along the timelike direction. A plethora of different regimes is identified, such as accelerated expansion, loitering, collapse, and tracking.
Discrete Abelian gauge symmetries and axions
NASA Astrophysics Data System (ADS)
Honecker, Gabriele; Staessens, Wieland
2015-07-01
We combine two popular extensions of beyond the Standard Model physics within the framework of intersecting D6-brane models: discrete ℤn symmetries and Peccei-Quinn axions. The underlying natural connection between both extensions is formed by the presence of massive U(1) gauge symmetries in D-brane model building. Global intersecting D6-brane models on toroidal orbifolds of the type T6/ℤ2N and T6/ℤ2 × ℤ2M with discrete torsion offer excellent playgrounds for realizing these extensions. A generation-dependent ℤ2 symmetry is identified in a global Pati-Salam model, while global left-right symmetric models give rise to supersymmetric realizations of the DFSZ axion model. In one class of the latter models, the axion as well as Standard Model particles carry a non-trivial ℤ3 charge.
Revolving D-branes and spontaneous gauge-symmetry breaking
NASA Astrophysics Data System (ADS)
Iso, Satoshi; Kitazawa, Noriaki
2015-12-01
We propose a new mechanism of spontaneous gauge-symmetry breaking in the world-volume theory of revolving D-branes around a fixed point of orbifolds. In this paper, we consider a simple model of the T^6/Z_3 orbifold on which we put D3-branes, D7-branes, and their anti-branes. The configuration breaks supersymmetry, but the Ramond-Ramond tadpole cancellation conditions are satisfied. A set of three D3-branes at an orbifold fixed point can separate from the point, but, when they move perpendicular to the anti-D7-branes put on the fixed point, they are pulled back due to an attractive interaction between the D3- and anti-D7-branes. In order to stabilize the separation of the D3-branes at nonzero distance, we consider revolution of the D3-branes around the fixed point. Then the gauge symmetry on the D3-branes is spontaneously broken, and the rank of the gauge group is reduced. The distance can be set at will by appropriately choosing the angular momentum of the revolving D3-branes, which should be determined by the initial condition of the cosmological evolution of the D-brane configurations. The distance corresponds to the vacuum expectation values of brane moduli fields in the world-volume theory and, if it is written as M/M_s^2 in terms of the string scale M_s, the scale of gauge-symmetry breaking is given by M. Angular momentum conservation of revolving D3-branes assures the stability of the scale M against M_s.
Duality, Gauge Symmetries, Renormalization Groups and the BKT Transition
NASA Astrophysics Data System (ADS)
José, Jorge V.
2013-06-01
In this chapter, I will briefly review, from my own perspective, the situation within theoretical physics at the beginning of the 1970s, and the advances that played an important role in providing a solid theoretical and experimental foundation for the Berezinskii-Kosterlitz-Thouless theory (BKT). Over this period, it became clear that the Abelian gauge symmetry of the 2D-XY model had to be preserved to get the right phase structure of the model. In previous analyses, this symmetry was broken when using low order calculational approximations. Duality transformations at that time for two-dimensional models with compact gauge symmetries were introduced by José, Kadanoff, Nelson and Kirkpatrick (JKKN). Their goal was to analyze the phase structure and excitations of XY and related models, including symmetry breaking fields which are experimentally important. In a separate context, Migdal had earlier developed an approximate Renormalization Group (RG) algorithm to implement Wilson's RG for lattice gauge theories. Although Migdal's RG approach, later extended by Kadanoff, did not produce a true phase transition for the XY model, it almost did asymptotically in terms of a non-perturbative expansion in the coupling constant with an essential singularity. Using these advances, including work done on instantons (vortices), JKKN analyzed the behavior of the spin-spin correlation functions of the 2D XY-model in terms of an expansion in temperature and vortex-pair fugacity. Their analysis led to a perturbative derivation of RG equations for the XY model which are the same as those first derived by Kosterlitz for the two-dimensional Coulomb gas. JKKN's results gave a theoretical formulation foundation and justification for BKT's sound physical assumptions and for the validity of their calculational approximations that were, in principle, strictly valid only at very low temperatures, away from the critical TBKT temperature. The theoretical predictions were soon tested
Duality, Gauge Symmetries, Renormalization Groups and the BKT Transition
NASA Astrophysics Data System (ADS)
José, Jorge V.
2017-03-01
In this chapter, I will briefly review, from my own perspective, the situation within theoretical physics at the beginning of the 1970s, and the advances that played an important role in providing a solid theoretical and experimental foundation for the Berezinskii-Kosterlitz-Thouless theory (BKT). Over this period, it became clear that the Abelian gauge symmetry of the 2D-XY model had to be preserved to get the right phase structure of the model. In previous analyses, this symmetry was broken when using low order calculational approximations. Duality transformations at that time for two-dimensional models with compact gauge symmetries were introduced by José, Kadanoff, Nelson and Kirkpatrick (JKKN). Their goal was to analyze the phase structure and excitations of XY and related models, including symmetry breaking fields which are experimentally important. In a separate context, Migdal had earlier developed an approximate Renormalization Group (RG) algorithm to implement Wilson’s RG for lattice gauge theories. Although Migdal’s RG approach, later extended by Kadanoff, did not produce a true phase transition for the XY model, it almost did asymptotically in terms of a non-perturbative expansion in the coupling constant with an essential singularity. Using these advances, including work done on instantons (vortices), JKKN analyzed the behavior of the spin-spin correlation functions of the 2D XY-model in terms of an expansion in temperature and vortex-pair fugacity. Their analysis led to a perturbative derivation of RG equations for the XY model which are the same as those first derived by Kosterlitz for the two-dimensional Coulomb gas. JKKN’s results gave a theoretical formulation foundation and justification for BKT’s sound physical assumptions and for the validity of their calculational approximations that were, in principle, strictly valid only at very low temperatures, away from the critical TBKT temperature. The theoretical predictions were soon tested
Invariance, symmetry and periodicity in gauge theories
Jackiw, R
1980-02-01
The interplay between gauge transformations and coordinate transformations is discussed; the theory will aid in understanding the mixing of space-time and internal degrees of freedom. The subject is presented under the following headings: coordinate transformation laws for arbitrary fields, coordinate transformation laws for gauge fields, properties of symmetric gauge fields, construction of symmetric gauge fields, physical significance of gauge transformations, and magnetic monopole topology without Higgs fields. The paper ends with conclusions and suggestions for further research. (RWR)
Renormalization of vacuum expectation values in spontaneously broken gauge theories
NASA Astrophysics Data System (ADS)
Sperling, Marcus; Stöckinger, Dominik; Voigt, Alexander
2013-07-01
We compute one-loop and two-loop β-functions for vacuum expectation values (VEVs) in gauge theories. In R ξ gauge the VEVs renormalize differently from the respective scalar fields. We focus particularly on the origin and behaviour of this difference and show that it can be interpreted as the anomalous dimension of a certain scalar background field, leading to simple direct computation and qualitative understanding. The results are given for generic as well as supersymmetric gauge theories. These complement the set of well-known γ- and β-functions of Machacek/Vaughn. As an application, we compute the β-functions for VEVs and tan β in the MSSM, NMSSM, and E6SSM.
Model for neutrino masses and dark matter with a discrete gauge symmetry
NASA Astrophysics Data System (ADS)
Chang, We-Fu; Wong, Chi-Fong
2012-01-01
A simple renormalizable U(1) gauge model is constructed to explain the smallness of the active neutrino masses and provide the stable cold dark matter candidate simultaneously. The local U(1) symmetry is assumed to be spontaneously broken by a scalar field around the TeV scale. The active neutrino masses are then generated at one-loop level. This model contains several cold dark matter candidates whose stability is guaranteed by a residual discrete gauge Z2 symmetry à la the Krauss-Wilczek mechanism. Unlike the other dark matter models, no further global discrete or continuous symmetry is introduced. Moreover, the masses of all fermionic degrees of freedom beyond the standard model are closely related to the scale of spontaneous breaking of U(1); thus they could be probed at or below the TeV scale. The possible cosmological and phenomenological consequences are briefly discussed.
On gauge independence for gauge models with soft breaking of BRST symmetry
NASA Astrophysics Data System (ADS)
Reshetnyak, Alexander
2014-12-01
A consistent quantum treatment of general gauge theories with an arbitrary gauge-fixing in the presence of soft breaking of the BRST symmetry in the field-antifield formalism is developed. It is based on a gauged (involving a field-dependent parameter) version of finite BRST transformations. The prescription allows one to restore the gauge-independence of the effective action at its extremals and therefore also that of the conventional S-matrix for a theory with BRST-breaking terms being additively introduced into a BRST-invariant action in order to achieve a consistency of the functional integral. We demonstrate the applicability of this prescription within the approach of functional renormalization group to the Yang-Mills and gravity theories. The Gribov-Zwanziger action and the refined Gribov-Zwanziger action for a many-parameter family of gauges, including the Coulomb, axial and covariant gauges, are derived perturbatively on the basis of finite gauged BRST transformations starting from Landau gauge. It is proved that gauge theories with soft breaking of BRST symmetry can be made consistent if the transformed BRST-breaking terms satisfy the same soft BRST symmetry breaking condition in the resulting gauge as the untransformed ones in the initial gauge, and also without this requirement.
Dirac or Inverse Seesaw Neutrino Masses from Gauged B - L Symmetry
NASA Astrophysics Data System (ADS)
Ma, Ernest; Srivastava, Rahul
The gauged B - L symmetry is one of the simplest and well studied extension of standard model. In the conventional case, addition of three singlet right-handed neutrinos each transforming as -1 under the B - L symmetry renders it anomaly free. It is usually assumed that the B - L symmetry is spontaneously broken by a singlet scalar having two units of B - L charge, resulting in a natural implementation of Majorana seesaw mechanism for neutrinos. However, as we discuss in this proceeding, there is another simple anomaly free solution which leads to Dirac or inverse seesaw masses for neutrinos. These new possibilities are explored along with an application to neutrino mixing with S3 flavour symmetry.
Photonic topological insulator with broken time-reversal symmetry.
He, Cheng; Sun, Xiao-Chen; Liu, Xiao-Ping; Lu, Ming-Hui; Chen, Yulin; Feng, Liang; Chen, Yan-Feng
2016-05-03
A topological insulator is a material with an insulating interior but time-reversal symmetry-protected conducting edge states. Since its prediction and discovery almost a decade ago, such a symmetry-protected topological phase has been explored beyond electronic systems in the realm of photonics. Electrons are spin-1/2 particles, whereas photons are spin-1 particles. The distinct spin difference between these two kinds of particles means that their corresponding symmetry is fundamentally different. It is well understood that an electronic topological insulator is protected by the electron's spin-1/2 (fermionic) time-reversal symmetry [Formula: see text] However, the same protection does not exist under normal circumstances for a photonic topological insulator, due to photon's spin-1 (bosonic) time-reversal symmetry [Formula: see text] In this work, we report a design of photonic topological insulator using the Tellegen magnetoelectric coupling as the photonic pseudospin orbit interaction for left and right circularly polarized helical spin states. The Tellegen magnetoelectric coupling breaks bosonic time-reversal symmetry but instead gives rise to a conserved artificial fermionic-like-pseudo time-reversal symmetry, Tp ([Formula: see text]), due to the electromagnetic duality. Surprisingly, we find that, in this system, the helical edge states are, in fact, protected by this fermionic-like pseudo time-reversal symmetry Tp rather than by the bosonic time-reversal symmetry Tb This remarkable finding is expected to pave a new path to understanding the symmetry protection mechanism for topological phases of other fundamental particles and to searching for novel implementations for topological insulators.
Photonic topological insulator with broken time-reversal symmetry
He, Cheng; Sun, Xiao-Chen; Liu, Xiao-Ping; Lu, Ming-Hui; Chen, Yulin; Feng, Liang; Chen, Yan-Feng
2016-01-01
A topological insulator is a material with an insulating interior but time-reversal symmetry-protected conducting edge states. Since its prediction and discovery almost a decade ago, such a symmetry-protected topological phase has been explored beyond electronic systems in the realm of photonics. Electrons are spin-1/2 particles, whereas photons are spin-1 particles. The distinct spin difference between these two kinds of particles means that their corresponding symmetry is fundamentally different. It is well understood that an electronic topological insulator is protected by the electron’s spin-1/2 (fermionic) time-reversal symmetry Tf2=−1. However, the same protection does not exist under normal circumstances for a photonic topological insulator, due to photon’s spin-1 (bosonic) time-reversal symmetry Tb2=1. In this work, we report a design of photonic topological insulator using the Tellegen magnetoelectric coupling as the photonic pseudospin orbit interaction for left and right circularly polarized helical spin states. The Tellegen magnetoelectric coupling breaks bosonic time-reversal symmetry but instead gives rise to a conserved artificial fermionic-like-pseudo time-reversal symmetry, Tp (Tp2=−1), due to the electromagnetic duality. Surprisingly, we find that, in this system, the helical edge states are, in fact, protected by this fermionic-like pseudo time-reversal symmetry Tp rather than by the bosonic time-reversal symmetry Tb. This remarkable finding is expected to pave a new path to understanding the symmetry protection mechanism for topological phases of other fundamental particles and to searching for novel implementations for topological insulators. PMID:27092005
Statistical Physics of Viral Capsids with Broken Symmetry
NASA Astrophysics Data System (ADS)
Perotti, L. E.; Rudnick, J.; Bruinsma, R. F.; Klug, W. S.
2015-07-01
We present a model to understand quantitatively the role of symmetry breaking in assembly of macromolecular aggregates in general, and the protein shells of viruses in particular. A simple dodecahedral lattice model with a quadrupolar order parameter allows us to demonstrate how symmetry breaking may reduce the probability of assembly errors and, consequently, enhance assembly efficiency. We show that the ground state is characterized by large-scale cooperative zero-energy modes. In analogy with other models, this suggests a general physical principle: the tendency of biological molecules to generate symmetric structures competes with the tendency to break symmetry in order to achieve specific functional goals.
Isotropy of Angular Frequencies and Weak Chimeras with Broken Symmetry
NASA Astrophysics Data System (ADS)
Bick, Christian
2017-04-01
The notion of a weak chimeras provides a tractable definition for chimera states in networks of finitely many phase oscillators. Here, we generalize the definition of a weak chimera to a more general class of equivariant dynamical systems by characterizing solutions in terms of the isotropy of their angular frequency vector—for coupled phase oscillators the angular frequency vector is given by the average of the vector field along a trajectory. Symmetries of solutions automatically imply angular frequency synchronization. We show that the presence of such symmetries is not necessary by giving a result for the existence of weak chimeras without instantaneous or setwise symmetries for coupled phase oscillators. Moreover, we construct a coupling function that gives rise to chaotic weak chimeras without symmetry in weakly coupled populations of phase oscillators with generalized coupling.
Variational Tricomplex, Global Symmetries and Conservation Laws of Gauge Systems
NASA Astrophysics Data System (ADS)
Sharapov, Alexey A.
2016-10-01
Using the concept of variational tricomplex endowed with a presymplectic structure, we formulate the general notion of symmetry. We show that each generalized symmetry of a gauge system gives rise to a sequence of conservation laws that are represented by on-shell closed forms of various degrees. This extends the usual Noether's correspondence between global symmetries and conservation laws to the case of lower-degree conservation laws and not necessarily variational equations of motion. Finally, we equip the space of conservation laws of a given degree with a Lie bracket and establish a homomorphism of the resulting Lie algebra to the Lie algebra of global symmetries.
NASA Astrophysics Data System (ADS)
Hsu, Jong-Ping
2014-02-01
A generalization of the usual gauge symmetry leads to fourth-order gauge field equations, which imply a new constant force independent of distances. The force associated with the new U1 gauge symmetry is repulsive among baryons. Such a constant force based on baryon charge conservation gives a field-theoretic understanding of the accelerated cosmic expansion in the observable portion of the universe dominated by baryon galaxies. In consistent with all conservation laws and known forces, a simple rotating "dumbbell model" of the universe is briefly discussed.
Z2 antiferromagnetic topological insulators with broken C4 symmetry
NASA Astrophysics Data System (ADS)
Bègue, Frédéric; Pujol, Pierre; Ramazashvili, Revaz
2017-04-01
A two-dimensional topological insulator may arise in a centrosymmetric commensurate Néel antiferromagnet (AF), where staggered magnetization breaks both the elementary translation and time reversal, but retains their product as a symmetry. Fang et al. [6] proposed an expression for a Z2 topological invariant to characterize such systems. Here, we show that this expression does not allow to detect all the existing phases if a certain lattice symmetry is lacking. We implement numerical techniques to diagnose topological phases of a toy Hamiltonian, and verify our results by computing the Chern numbers of degenerate bands, and also by explicitly constructing the edge states, thus illustrating the efficiency of the method.
NASA Technical Reports Server (NTRS)
Baskaran, G.
1989-01-01
Using a nonmean-field approach the triangular-lattice S = 1/2 Heisenberg antiferromagnet with nearest- and next-nearest-neighbor couplings is shown undergo an Ising-type phase transition into a chiral-symmetry-broken phase (Kalmeyer-Laughlin-like state) at small T. Removal of next-nearest-neighbor coupling introduces a local Z2 symmetry, thereby suppressing any finite-T chiral order.
Contraction of broken symmetries via Kac-Moody formalism
NASA Astrophysics Data System (ADS)
Daboul, Jamil
2006-08-01
I investigate contractions via Kac-Moody formalism. In particular, I show how the symmetry algebra of the standard two-dimensional Kepler system, which was identified by Daboul and Slodowy as an infinite-dimensional Kac-Moody loop algebra, and was denoted by H2, gets reduced by the symmetry breaking term, defined by the Hamiltonian H(β )=(1/2m)(p12+p22)-α/r-βr-1/2cos((φ-γ)/2). For this H(β ) I define two symmetry loop algebras Li(β), i =1,2, by choosing the "basic generators" differently. These Li(β) can be mapped isomorphically onto subalgebras of H2, of codimension two or three, revealing the reduction of symmetry. Both factor algebras Li(β)/Ii(E,β), relative to the corresponding energy-dependent ideals Ii(E,β), are isomorphic to so(3) and so(2,1) for E <0 and E >0, respectively, just as for the pure Kepler case. However, they yield two different nonstandard contractions as E →0, namely to the Heisenberg-Weyl algebra h3=w1 or to an Abelian Lie algebra, instead of the Euclidean algebra e(2) for the pure Kepler case. The above-noted example suggests a general procedure for defining generalized contractions, and also illustrates the "deformation contraction hysteresis," where contraction which involves two contraction parameters can yield different contracted algebras, if the limits are carried out in different order.
Enhanced gauge symmetries on elliptic K3
NASA Astrophysics Data System (ADS)
Bonora, L.; Reina, C.; Zampa, A.
1999-04-01
We show that the geometry of K3 surfaces with singularities of type A-D-E contains enough information to reconstruct a copy of the Lie algebra associated to the given Dynkin diagram. We apply this construction to explain the enhancement of symmetry in F and IIA theories compactified on singular K3's.
NASA Astrophysics Data System (ADS)
Xia, Baizhan; Dai, Hongqing; Yu, Dejie
2016-06-01
Metamaterials offer extraordinary possibilities for manipulating the propagation of the sound wave in a subwavelength scale. However, the design of acoustic metamaterials remains challenging with traditional strategies, employing two different types of acoustic resonators simultaneously or using specific substructures with multiple resonances. Here we design a symmetry-broken metamaterial comprising of only Helmholtz resonators whose periodical spatial arrangements are broken. The symmetry-broken metamaterials form a hollow hexagonal resonant absorber with two significant resonances. One is the monopolar resonance presenting a collective in-phase pattern motion independent of angle. The other is the dipolar resonance originating from the multiple scattering of symmetry-broken metamaterials. By concentrating the sound energy in peaks of their modes, the hollow hexagonal resonant absorber with extremely small filling ratio can be effectively used to block the propagation of the sound wave in a low-frequency range between monopolar and dipolar resonances. Numerical results also show that the symmetry-broken metamaterials with careful arrangement can be applied to the sound cloaking and the sound supertunneling.
Observation and elimination of broken symmetry in L1{sub 0} FePt nanostructures
Quarterman, P.; Wang, Hao; Qiu, Jiao-Ming; Ma, Bin; Liu, Xiaoqi; Wang, Jian-Ping; Guo, Honghua
2015-12-07
An unexplained surface anisotropy effect was observed and confirmed in the magnetization reversal process of both L1{sub 0} phase FePt nanoparticles with octahedral shape and (001) textured L1{sub 0} FePt thin films with island nanostructures. We suggest that the nature of the observed surface effect is caused by broken symmetry on the FePt surface, which results in weakened exchange coupling for surface atoms. Furthermore, we propose, and experimentally demonstrate, a method to repair the broken symmetry by capping the FePt islands with a Pt layer, which could prove invaluable in understanding fundamental limitations of magnetic nanostructures.
NASA Astrophysics Data System (ADS)
Krowne, Clifford M.
2004-07-01
Heterostructure arrangements of uniaxial bicrystals have been discovered to produce electromagnetic fields with asymmetric distributions in guide wave structures. The property behind this remarkable phenomenon is the broken crystalline symmetry which allows the new physics to be seen in unsymmetric distributions. Here the theory behind this phenomenon is presented, numerical calculations are performed using an ab initio anisotropic Green’s function approach, and the results provided at 10 GHz for a realistic crystal system with nominal permittivity of 5. Asymmetric distributions seen here are one facet of the broken symmetry property which generates negative refraction for impinging waves on a bicrystal.
Gauge Theories and Spontaneous Symmetry Breaking.
1980-11-01
breaking spontaneous symmetric breaking , Higgs mechanism bifurcation problem RATr0ACT’fwwdhn om pea71 Ul nonmevi dumad #~lyb block Im.,) his report is a...field theories. It was felt that the symmetry breaking used by the physicists LiI (a procedure known as the Higgs mechanism) is not precisely a...feeling, after some discussions, that the symmctry breaking used by the phyalciuts (a procedure known as the Higgs mechanism) is not precisely a
Classically conformal radiative neutrino model with gauged B - L symmetry
NASA Astrophysics Data System (ADS)
Okada, Hiroshi; Orikasa, Yuta
2016-09-01
We propose a classically conformal model in a minimal radiative seesaw, in which we employ a gauged B - L symmetry in the standard model that is essential in order to work the Coleman-Weinberg mechanism well that induces the B - L symmetry breaking. As a result, nonzero Majorana mass term and electroweak symmetry breaking simultaneously occur. In this framework, we show a benchmark point to satisfy several theoretical and experimental constraints. Here theoretical constraints represent inert conditions and Coleman-Weinberg condition. Experimental bounds come from lepton flavor violations (especially μ → eγ), the current bound on the Z‧ mass at the CERN Large Hadron Collider, and neutrino oscillations.
Evidence for a Phase with Broken Translational Symmetry
Emelyanov, S. A.; Ivanov, S. V.
2011-12-23
We report on the discovering of a quantum phase which possesses neither continuous nor discrete translational symmetry. The phase emerges from the Quantum Hall state of matter and is induced by a toroidal moment which is a cross product of 'built-in' transverse electric field and tilted quantizing magnetic field. The phase is detected by the method of terahertz photo-voltaic spectroscopy which is insensitive to the vast majority of electrons remaining in conventional Quantum Hall states. The electrons in the new phase are demonstrated to have spatially-separated macroscopic-scale orbitlike wavefunctions distributed over a macroscopic sample with no spatial periodicity.
SU(2) gauge symmetry in gravity phase space
NASA Astrophysics Data System (ADS)
Cianfrani, Francesco
2012-05-01
The Hamiltonian formulation of the Holst action in vacuum and in the presence of matter fields is analyzed in a generic local Lorentz frame. It is elucidated how the SU(2) gauge symmetry is inferred by reducing the set of constraints to a first-class one. The consequences of the proposed approach for Loop Quantum Gravity and Spin Foam models are discussed.
The diversity of type Ia supernovae from broken symmetries.
Kasen, D; Röpke, F K; Woosley, S E
2009-08-13
Type Ia supernovae result when carbon-oxygen white dwarfs in binary systems accrete mass from companion stars, reach a critical mass and explode. The near uniformity of their light curves makes these supernovae good 'standard candles' for measuring cosmic expansion, but a correction must be applied to account for the fact that the brighter ones have broader light curves. One-dimensional modelling, with a certain choice of parameters, can reproduce this general trend in the width-luminosity relation; but the processes of ignition and detonation have recently been shown to be intrinsically asymmetric, so parameterization must have its limits. Here we report multi-dimensional modelling of the explosion physics and radiative transfer, which reveals that the breaking of spherical symmetry is a critical factor in determining both the width-luminosity relation and the observed scatter about it. The deviation from spherical symmetry can also explain the finite polarization detected in the light from some supernovae. The slope and normalization of the width-luminosity relation has a weak dependence on certain properties of the white dwarf progenitor, in particular the trace abundances of elements other than carbon and oxygen. Failing to correct for this effect could lead to systematic overestimates of up to 2 per cent in the distance to remote supernovae.
Normal forms and gauge symmetry of local dynamics
NASA Astrophysics Data System (ADS)
Lyakhovich, S. L.; Sharapov, A. A.
2009-08-01
A systematic procedure is proposed for deriving all the gauge symmetries of the general, not necessarily variational, equations of motion. For the variational equations, this procedure reduces to the Dirac-Bergmann algorithm for the constrained Hamiltonian systems with certain extension: it remains applicable beyond the scope of Dirac's conjecture. Even though no pairing exists between the constraints and the gauge symmetry generators in general nonvariational dynamics, certain counterparts still can be identified of the first- and second-class constraints without appealing to any Poisson structure. It is shown that the general local gauge dynamics can be equivalently reformulated in an involutive normal form. The last form of dynamics always admits the BRST embedding, which does not require the classical equations to follow from any variational principle.
Exact solutions with noncommutative symmetries in Einstein and gauge gravity
NASA Astrophysics Data System (ADS)
Vacaru, Sergiu I.
2005-04-01
We present new classes of exact solutions with noncommutative symmetries constructed in vacuum Einstein gravity (in general, with nonzero cosmological constant), five-dimensional (5D) gravity and (anti) de Sitter gauge gravity. Such solutions are generated by anholonomic frame transforms and parametrized by generic off-diagonal metrics. For certain particular cases, the new classes of metrics have explicit limits with Killing symmetries but, in general, they may be characterized by certain anholonomic noncommutative matrix geometries. We argue that different classes of noncommutative symmetries can be induced by exact solutions of the field equations in commutative gravity modeled by a corresponding moving real and complex frame geometry. We analyze two classes of black ellipsoid solutions (in the vacuum case and with cosmological constant) in four-dimensional gravity and construct the analytic extensions of metrics for certain classes of associated frames with complex valued coefficients. The third class of solutions describes 5D wormholes which can be extended to complex metrics in complex gravity models defined by noncommutative geometric structures. The anholonomic noncommutative symmetries of such objects are analyzed. We also present a descriptive account how the Einstein gravity can be related to gauge models of gravity and their noncommutative extensions and discuss such constructions in relation to the Seiberg-Witten map for the gauge gravity. Finally, we consider a formalism of vielbeins deformations subjected to noncommutative symmetries in order to generate solutions for noncommutative gravity models with Moyal (star) product.
Mirror symmetry in three dimensions via gauged linear quivers
NASA Astrophysics Data System (ADS)
Dey, Anindya; Hanany, Amihay; Koroteev, Peter; Mekareeya, Noppadol
2014-06-01
Starting from mirror pairs consisting only of linear (framed A-type) quivers, we demonstrate that a wide class of three-dimensional quiver gauge theories with = 4 supersymmetry and their mirror duals can be obtained by suitably gauging flavor symmetries. Infinite families of mirror pairs including various quivers of D and E-type and their affine extensions, star-shaped quivers, and quivers with symplectic gauge groups may be generated in this fashion. We present two different computational strategies to perform the aforementioned gauging procedure — one of them involves = 2* classical parameter space description, while the other one uses partition functions of the = 4 theories on S 3. The partition function, in particular, turns out to be an extremely efficient tool for implementing this gauging procedure as it readily generalizes to arbitrary size of the quiver and arbitrary rank of the gauge group at each node. For most examples of mirror pairs obtained via this procedure, we perform additional checks of mirror symmetry using the Hilbert series.
Broken flavor symmetries in high energy particle phenomenology
Antaramian, Aram
1995-02-22
Over the past couple of decades, the Standard Model of high energy particle physics has clearly established itself as an invaluable tool in the analysis of high energy particle phenomenon. However, from a field theorists point of view, there are many dissatisfying aspects to the model. One of these, is the large number of free parameters in the theory arising from the Yukawa couplings of the Higgs doublet. In this thesis, we examine various issues relating to the Yukawa coupeng structure of high energy particle field theories. We begin by examining extensions to the Standard Model of particle physics which contain additional scalar fields. By appealing to the flavor structure observed in the fermion mass and Kobayashi-Maskawa matrices, we propose a reasonable phenomenological parameterization of the new Yukawa couplings based on the concept of approximate flavor symmetries. It is shown that such a parameterization eliminates the need for discrete symmetries which limit the allowed couplings of the new scalars. New scalar particles which can mediate exotic flavor changing reactions can have masses as low as the weak scale. Next, we turn to the issue of neutrino mass matrices, where we examine a particular texture which leads to matter independent neutrino oscillation results for solar neutrinos. We, then, examine the basis for extremely strict limits placed on flavor changing interactions which also break lepton- and/or baryon-number. These limits are derived from cosmological considerations. Finally, we embark on an extended analysis of proton decay in supersymmetric SO(10) grand unified theories. In such theories, the dominant decay diagrams involve the Yukawa couplings of a heavy triplet superfield. We argue that past calculations of proton decay which were based on the minimal supersymmetric SU(5) model require reexamination because the Yukawa couplings of that theory are known to be wrong.
NASA Astrophysics Data System (ADS)
Peletminskii, A. S.; Peletminskii, S. V.
2009-08-01
We construct a Lagrangian describing the low-frequency dynamics of a system with spontaneously broken phase and translational symmetry (a supersolid). Using the principle of stationary action, we obtain the hydrodynamic equations for the considered system. We give a relativistic generalization of the obtained equations of motion in terms of the the Gibbs thermodynamic potential density.
Broken symmetry dielectric resonators for high quality factor Fano metasurfaces
Campione, Salvatore; Liu, Sheng; Basilio, Lorena I.; Warne, Larry K.; Langston, William L.; Luk, Ting S.; Wendt, Joel R.; Reno, John L.; Keeler, Gordon A.; Brener, Igal; Sinclair, Michael B.
2016-10-25
We present a new approach to dielectric metasurface design that relies on a single resonator per unit cell and produces robust, high quality factor Fano resonances. Our approach utilizes symmetry breaking of highly symmetric resonator geometries, such as cubes, to induce couplings between the otherwise orthogonal resonator modes. In particular, we design perturbations that couple “bright” dipole modes to “dark” dipole modes whose radiative decay is suppressed by local field effects in the array. Our approach is widely scalable from the near-infrared to radio frequencies. We first unravel the Fano resonance behavior through numerical simulations of a germanium resonator-based metasurface that achieves a quality factor of ~1300 at ~10.8 μm. Then, we present two experimental demonstrations operating in the near-infrared (~1 μm): a silicon-based implementation that achieves a quality factor of ~350; and a gallium arsenide-based structure that achieves a quality factor of ~600, the highest near-infrared quality factor experimentally demonstrated to date with this kind of metasurface. Importantly, large electromagnetic field enhancements appear within the resonators at the Fano resonant frequencies. Here, we envision that combining high quality factor, high field enhancement resonances with nonlinear and active/gain materials such as gallium arsenide will lead to new classes of active optical devices.
Broken symmetry dielectric resonators for high quality factor Fano metasurfaces
Campione, Salvatore; Liu, Sheng; Basilio, Lorena I.; ...
2016-10-25
We present a new approach to dielectric metasurface design that relies on a single resonator per unit cell and produces robust, high quality factor Fano resonances. Our approach utilizes symmetry breaking of highly symmetric resonator geometries, such as cubes, to induce couplings between the otherwise orthogonal resonator modes. In particular, we design perturbations that couple “bright” dipole modes to “dark” dipole modes whose radiative decay is suppressed by local field effects in the array. Our approach is widely scalable from the near-infrared to radio frequencies. We first unravel the Fano resonance behavior through numerical simulations of a germanium resonator-based metasurfacemore » that achieves a quality factor of ~1300 at ~10.8 μm. Then, we present two experimental demonstrations operating in the near-infrared (~1 μm): a silicon-based implementation that achieves a quality factor of ~350; and a gallium arsenide-based structure that achieves a quality factor of ~600, the highest near-infrared quality factor experimentally demonstrated to date with this kind of metasurface. Importantly, large electromagnetic field enhancements appear within the resonators at the Fano resonant frequencies. Here, we envision that combining high quality factor, high field enhancement resonances with nonlinear and active/gain materials such as gallium arsenide will lead to new classes of active optical devices.« less
Quench of a symmetry-broken ground state
NASA Astrophysics Data System (ADS)
Giampaolo, S. M.; Zonzo, G.
2017-01-01
We analyze the problem of how different ground states associated with the same set of Hamiltonian parameters evolve after a sudden quench. To realize our analysis we define a quantitative approach to the local distinguishability between different ground states of a magnetically ordered phase in terms of the trace distance between the reduced density matrices obtained by projecting two ground states in the same subset. Before the quench, regardless of the particular choice of subset, any system in a magnetically ordered phase is characterized by ground states that are locally distinguishable. On the other hand, after the quench, the maximum distinguishability shows an exponential decay in time. Hence, in the limit of very long times, all the information about the particular initial ground state is lost even if the systems are integrable. We prove our claims in the framework of the magnetically ordered phases that characterize both the X Y and the N -cluster Ising models. The fact that we find similar behavior in models within different classes of symmetry makes us confident about the generality of our results.
NASA Astrophysics Data System (ADS)
Dütsch, Michael
2015-12-01
The usual derivation of the Lagrangian of a model for massive vector bosons, by spontaneous symmetry breaking of a gauge theory, implies that the prefactors of the various interaction terms are uniquely determined functions of the coupling constant(s) and the masses. Since, under the renormalization group (RG) flow, different interaction terms get different loop-corrections, it is uncertain whether these functions remain fixed under this flow. We investigate this question for the U(1)-Higgs-model to 1-loop order in the framework of Epstein-Glaser renormalization. Our main result reads: choosing the renormalization mass scale(s) in a way corresponding to the minimal subtraction scheme, the geometrical interpretation as a spontaneously broken gauge theory gets lost under the RG-flow. This holds also for the clearly stronger property of BRST-invariance of the Lagrangian. On the other hand, we prove that physical consistency, which is a weak form of BRST-invariance of the time-ordered products, is maintained under the RG-flow.
Long lived superheavy dark matter with discrete gauge symmetries
NASA Astrophysics Data System (ADS)
Hamaguchi, K.; Nomura, Yasunori; Yanagida, T.
1999-03-01
The recently observed ultrahigh energy (UHE) cosmic rays beyond the Greisen-Zatsepin-Kuzmin bound can be explained by the decays of some superheavy X particles forming a part of dark matter in our universe. We consider various discrete gauge symmetries ZN to ensure the required long lifetime (τX~=1010-1022 yr) of the X particle to explain the UHE cosmic rays in the minimal supersymmetric standard model (MSSM) with massive Majorana neutrinos. We show that there is no anomaly-free discrete gauge symmetry to make the lifetime of the X particle sufficiently long in the MSSM with the X particle. We find, however, possible solutions to this problem especially by enlarging the particle contents in the MSSM. We show a number of solutions introducing an extra pair of singlets Y and Y¯ which have fractional ZN(N=2,3) charges. The present experimental constraints on the X particle are briefly discussed.
NASA Astrophysics Data System (ADS)
Bozin, Emil; Zhong, R.; Knox, K. R.; Winn, B. L.; Gu, G. D.; Hill, J. P.; Tranquada, J. M.; Billinge, S. J. L.
2015-03-01
Revealing the nature of the symmetry broken states in strongly correlated electron systems in general, and in the pseudo-gap (PG) phase of cuprates in particular, is instrumental in understanding the underlying properties. To that effect the knowledge of the local atomic structure may reveal relevant details important for more comprehensive understanding of the character of symmetry broken states in strongly correlated electron systems. Atomic pair distribution function (PDF) is one of the few experimental methods that can speak to this problem. Mounting experimental evidence suggests that the pseudogap phase may represent an electronic state in which the four-fold rotational symmetry of the CuO2 planes is broken, pointing to stripe or nematic character. Systematic approach has been taken in charting both long and short range structural orders, on an equal footing, across the (x, T) phase diagrams of cuprates. For example, in La2-xBaxCuO4, by combining inelastic neutron scattering and neutron PDF approaches, we find evidence consistent with there being a dynamic symmetry breaking well above the charge ordering temperature and within the pseudogap regime. The response has non-monotonic doping dependence that peaks at 1/8 composition. Work at Brookhaven National Laboratory was supported by US DOE, Office of Science, Office of Basic Energy Sciences (DOE-BES) under Contract DE-AC02-98CH10886.
Gauge symmetry breaking in gravity and auxiliary effective action
NASA Astrophysics Data System (ADS)
Akhavan, Amin
2017-02-01
In the context of the covariant symmetry breaking in gravity, we study the quantum aspect of Chamseddine-Mukhanov model by making use of path integral method. Utilizing one of the gauge fixing constraints, we remove the specific ghost degree of freedom. In continuation, we define an auxiliary effective action. Introducing an auxiliary field, we will have a new dynamic field in addition to the fundamental field.
Alfv'en mode structure/stability properties of stellarators and broken-symmetry tokamaks
NASA Astrophysics Data System (ADS)
Spong, Don
2009-05-01
Energetic particle driven shear Alfv'en wave (SAW) instabilities are frequently observed in both stellarator and tokamak experiments. Three-dimensional effects are present in all toroidal devices and can significantly influence both stability properties of energetic particle populations and their loss patterns on the first wall. Three-dimensional equilibrium variations in stellarators and broken symmetry tokamaks provide new couplings that increase the complexity and density of the Alfv'en mode spectrum. An eigenmode solver, the AE3D code, has been developed for calculating Alfv'en mode structures in such configurations and identifying the most likely modes for resonant energetic tail destabilization. Applications of this model to a variety of stellarators (LHD, TJ-II, HSX, QPS, NCSX) and broken symmetry tokamaks (ITER with TF ripple and ferritic materials) have been made and results will be presented. Possible extensions to include sound wave couplings and gyro-Landau closures will be discussed.
Broken bond symmetry assists stripe pinning in superconducting La2-xSrxCuO4
NASA Astrophysics Data System (ADS)
Tranquada, John; Jacobsen, H.; Zaliznyak, I. A.; Huecker, M.; Gu, G. D.; Savici, A. T.; Winn, B.; Chang, S.
There has been evidence for quite some time for some degree of charge and spin stripe order in La2-xSrxCuO4 (LSCO). This has been a bit surprising as the crystal structure is supposed to lack the anisotropic Cu-O bonds that lead to robust stripe pinning in La2-xBaxCuO4. Using neutron scattering measurements on the HYSPEC instrument at the Spallation Neutron Source, we have discovered evidence for broken bond symmetry and strong associated lattice fluctuations in an LSCO crystal with x = 0 . 07. The broken bond symmetry occurs within the orthorhombic phase. We also observe quasielastic incommensurate spin excitations that coexist with the bulk superconductivity, suggesting some degree of pair-density-wave order in the superconducting state. Work at BNL supported by Office of Basic Energy Sciences, US DOE, under Contract No. DE-SC00112704.
Efficiency Statistics and Bounds for Systems with Broken Time-Reversal Symmetry.
Jiang, Jian-Hua; Agarwalla, Bijay Kumar; Segal, Dvira
2015-07-24
Universal properties of the statistics of stochastic efficiency for mesoscopic time-reversal symmetry broken energy transducers are revealed in the Gaussian approximation. We also discuss how the second law of thermodynamics restricts the statistics of stochastic efficiency. The tight-coupling limit becomes unfavorable, characterized by an infinitely broad distribution of efficiency at all times, when time-reversal symmetry breaking leads to an asymmetric Onsager response matrix. The underlying physics is demonstrated through the quantum Hall effect and further elaborated in a triple-quantum-dot three-terminal thermoelectric engine.
Consequences of Broken Translational Symmetry in FeSexTe1-x
NASA Astrophysics Data System (ADS)
Moreschini, L.; Lin, P.-H.; Lin, C.-H.; Ku, W.; Innocenti, D.; Chang, Y. J.; Walter, A. L.; Kim, K. S.; Brouet, V.; Yeh, K.-W.; Wu, M.-K.; Rotenberg, E.; Bostwick, A.; Grioni, M.
2014-02-01
We investigate the consequences of broken translational symmetry in the superconductor FeSexTe1-x using angle-resolved photoemission spectroscopy. We find that the intensity does not follow the periodicity dictated by the crystal structure, owing to the form of the perturbing potential and the symmetries of the Fe d orbitals. Their interplay leads to substantial differences in the orbital character and spectral features observed at nominally equivalent locations in the reciprocal space. Such differences cannot be accounted for by the usual dipole matrix element effects and are due instead to the structure factor, which must be explicitly considered whenever more than one atom is present in the unit cell.
Peccei-Quinn invariant singlet extended SUSY with anomalous U(1) gauge symmetry
NASA Astrophysics Data System (ADS)
Im, Sang Hui; Seo, Min-Seok
2015-05-01
Recent discovery of the SM-like Higgs boson with m h ≃ 125 GeV motivates an extension of the minimal supersymmetric standard model (MSSM), which involves a singlet Higgs superfield with a sizable Yukawa coupling to the doublet Higgs superfields. We examine such singlet-extended SUSY models with a Peccei-Quinn (PQ) symmetry that originates from an anomalous U(1) A gauge symmetry. We focus on the specific scheme that the PQ symmetry is spontaneously broken at an intermediate scale v PQ ˜ m SUSY M Pl by an interplay between Planck scale suppressed operators and tachyonic soft scalar mass induced dominantly by the U(1) A D-term D A . This scheme also results in spontaneous SUSY breaking in the PQ sector, generating the gaugino masses when it is transmitted to the MSSM sector by the conventional gauge mediation mechanism. As a result, the MSSM soft parameters in this scheme are induced mostly by the U(1) A D-term and the gauge mediated SUSY breaking from the PQ sector, so that the sparticle masses can be near the present experimental bounds without causing the SUSY flavor problem. The scheme is severely constrained by the condition that a phenomenologically viable form of the low energy operators of the singlet and doublet Higgs superfields is generated by the PQ breaking sector in a way similar to the Kim-Nilles solution of the μ problem, and the resulting Higgs mass parameters allow the electroweak symmetry breaking with small tan β. We find two minimal models with two singlet Higgs superfields, satisfying this condition with a relatively simple form of the PQ breaking sector, and briefly discuss some phenomenological aspects of the model.
BCS-BEC crossover at finite temperature in the broken-symmetry phase
NASA Astrophysics Data System (ADS)
Pieri, P.; Pisani, L.; Strinati, G. C.
2004-09-01
The BCS-BEC crossover is studied in a systematic way in the broken-symmetry phase between zero temperature and the critical temperature. This study bridges two regimes where quantum and thermal fluctuations are, respectively, important. The theory is implemented on physical grounds, by adopting a fermionic self-energy in the broken-symmetry phase that represents fermions coupled to superconducting fluctuations in weak coupling and to bosons described by the Bogoliubov theory in strong coupling. This extension of the theory beyond mean field proves important at finite temperature, to connect with the results in the normal phase. The order parameter, the chemical potential, and the single-particle spectral function are calculated numerically for a wide range of coupling and temperature. This enables us to assess the quantitative importance of superconducting fluctuations in the broken-symmetry phase over the whole BCS-BEC crossover. Our results are relevant to the possible realizations of this crossover with high-temperature cuprate superconductors and with ultracold fermionic atoms in a trap.
Controlling active self-assembly through broken particle-shape symmetry.
Wensink, H H; Kantsler, V; Goldstein, R E; Dunkel, J
2014-01-01
Many structural properties of conventional passive materials are known to arise from the symmetries of their microscopic constituents. By contrast, it is largely unclear how the interplay between particle shape and self-propulsion controls the meso- and macroscale behavior of active matter. Here we use large-scale simulations of homo- and heterogeneous self-propelled particle systems to identify generic effects of broken particle-shape symmetry on collective motion. We find that even small violations of fore-aft symmetry lead to fundamentally different collective behaviors, which may facilitate demixing of differently shaped species as well as the spontaneous formation of stable microrotors. These results suggest that variation of particle shape yields robust physical mechanisms to control self-assembly of active matter, with possibly profound implications for biology and materials design.
Signatures of broken parity and time-reversal symmetry in generalized string-net models
NASA Astrophysics Data System (ADS)
Lake, Ethan; Wu, Yong-Shi
2016-09-01
We study indicators of broken time-reversal and parity symmetries in gapped topological phases of matter. We focus on phases realized by Levin-Wen string-net models and generalize the string-net model to describe phases which break parity and time-reversal symmetries. We do this by introducing an extra degree of freedom into the string-net graphical calculus, which takes the form of a branch cut located at each vertex of the underlying string-net lattice. We also work with string-net graphs defined on arbitrary (nontrivalent) graphs, which reveals otherwise hidden information about certain configurations of anyons in the string-net graph. Most significantly, we show that objects known as higher Frobenius-Schur indicators can provide several efficient ways to detect whether a given topological phase breaks parity or time-reversal symmetry.
Unconventional pairings and radial line nodes in inversion symmetry broken superconductors
NASA Astrophysics Data System (ADS)
Hakioğlu, T.; Günay, Mehmet
2016-09-01
Noncentrosymmetric superconductors (NCSs) with broken inversion symmetry can have spin-dependent order parameters (OPs) with mixed parity which can also have nodes in the pair potential as well as the energy spectra. These nodes are distinct features that are not present in conventional superconductors. They appear as points or lines in the momentum space where the latter can have angular or radial geometries dictated by the dimensionality, the lattice structure and the pairing interaction. In this work we study the nodes in time reversal symmetry (TRS) preserving NCSs at the OP, the pair potential, and the energy spectrum levels. Nodes are examined by using spin independent pairing interactions respecting the rotational C∞v symmetry in the presence of spin-orbit coupling (SOC). The pairing symmetries and the nodal topology are affected by the relative strength of the pairing channels which is studied for the mixed singlet-triplet, pure singlet, and pure triplet. Complementary to the angular line nodes widely present in the literature, the C∞v symmetry here allows radial line nodes (RLNs) due to the nonlinear momentum dependence in the OPs. The topology of the RLNs in the mixed case shows a distinctly different characterization than the half-spin quantum vortex at the Dirac point. We apply this NCS physics to the inversion symmetry broken exciton condensates (ECs) in double quantum wells where the point and the RLNs can be found. On the other hand, for a pure triplet condensate, two fully gapped and topologically distinct regimes exist, separated by a QSHI-like zero energy superconducting state with even number of Majorana modes. We also remark on how the point and the RLNs can be manipulated, enabling an external control on the topology.
Gauge transformation and symmetries of the commutative multicomponent BKP hierarchy
NASA Astrophysics Data System (ADS)
Li, Chuanzhong
2016-01-01
In this paper, we defined a new multi-component B type Kadomtsev-Petviashvili (BKP) hierarchy that takes values in a commutative subalgebra of {gl}(N,{{C}}). After this, we give the gauge transformation of this commutative multicomponent BKP (CMBKP) hierarchy. Meanwhile, we construct a new constrained CMBKP hierarchy that contains some new integrable systems, including coupled KdV equations under a certain reduction. After this, the quantum torus symmetry and quantum torus constraint on the tau function of the commutative multi-component BKP hierarchy will be constructed.
NASA Astrophysics Data System (ADS)
Randeria, Mohit; Banerjee, Sumilan; Rowland, James
2015-09-01
Most theoretical studies of chiral magnetism, and the resulting spin textures, have focused on 3D systems with broken bulk inversion symmetry, where skyrmions are stabilized by easy-axis anisotropy. In this talk I will describe our results on 2D and quasi-2D systems with broken surface inversion, where we find [1] that skyrmion crystals are much more stable than in 3D, especially for the case of easy-plane anisotropy. These results are of particular interest for thin films, surfaces, and oxide interfaces [2], where broken surface-inversion symmetry and Rashba spin-orbit coupling naturally lead to both the chiral Dzyaloshinskii-Moriya (DM) interaction and to easy-plane compass anisotropy. I will then turn to systems that break both bulk and surface inversion, resulting in two distinct DM terms arising from Dresselhaus and Rashba spin-orbit coupling. I will describe [3] the evolution of the skyrmion structure and of the phase diagram as a function of the ratio of Dresselhaus and Rashba terms, which can be tuned by varying film thickness and strain. [1] S. Banerjee, J. Rowland, O. Erten, and M. Randeria, PRX 4, 031045 (2014). [2] S. Banerjee, O. Erten, and M. Randeria, Nature Phys. 9, 626 (2013). [3] J. Rowland, S. Banerjee and M. Randeria, (unpublished).
On (Un)Broken Higher-Spin Symmetry in Vector Models
NASA Astrophysics Data System (ADS)
Skvortsov, E. D.
The simplest consequences of exact and broken higher-spin symmetry are studied. The one-loop anomalous dimensions of higher-spin currents are determined from the multiplet recombination in the spirit of the modern bootstrap programme: the Wilson-Fisher CFT is studied both in the 4-ɛ-expansion and in the large-N. The bulk implications are briefly addressed: part of the higher-spin theory cubic action is reconstructed; one-loop corrections to the AdS masses of higher-spin fields are discussed.
LHC Higgs signatures from extended electroweak gauge symmetry
NASA Astrophysics Data System (ADS)
Abe, Tomohiro; Chen, Ning; He, Hong-Jian
2013-01-01
We study LHC Higgs signatures from the extended electroweak gauge symmetry SU(2) ⊗ SU(2) ⊗ U(1). Under this gauge structure, we present an effective UV completion of the 3-site moose model with ideal fermion delocalization, which contains two neutral Higgs states ( h, H) plus three new gauge bosons ( W ' , Z '). We study the unitarity, and reveal that the exact E 2 cancellation in the longitudinal V L V L scattering amplitudes is achieved by the joint role of exchanging both spin-1 new gauge bosons W ' /Z ' and spin-0 Higgs bosons h/H. We identify the lighter Higgs state h with mass 125 GeV, and derive the unitarity bound on the mass of heavier Higgs boson H. The parameter space of this model is highly predictive. We study the production and decay signals of this 125 GeV Higgs boson h at the LHC. We demonstrate that the h Higgs boson can naturally have enhanced signals in the diphoton channel gg → h → γγ, while the event rates in the reactions gg → h → W W ∗ and gg → h → ZZ ∗ are generally suppressed relative to the SM expectation. Searching the h Higgs boson via the associated production and the vector boson fusions are also discussed for our model. We further analyze the LHC signals of the heavier Higgs boson H as a new physics discriminator from the SM. For wide mass-ranges of H, we derive constraints from the existing LHC searches, and study the discovery potential of H at the LHC (8 TeV) and LHC (14 TeV).
Schemm, E R; Gannon, W J; Wishne, C M; Halperin, W P; Kapitulnik, A
2014-07-11
Models of superconductivity in unconventional materials can be experimentally differentiated by the predictions they make for the symmetries of the superconducting order parameter. In the case of the heavy-fermion superconductor UPt3, a key question is whether its multiple superconducting phases preserve or break time-reversal symmetry (TRS). We tested for asymmetry in the phase shift between left and right circularly polarized light reflected from a single crystal of UPt3 at normal incidence and found that this so-called polar Kerr effect appears only below the lower of the two zero-field superconducting transition temperatures. Our results provide evidence for broken TRS in the low-temperature superconducting phase of UPt3, implying a complex two-component order parameter for superconductivity in this system.
Spontaneously broken asymptotic symmetries and an effective action for horizon dynamics
NASA Astrophysics Data System (ADS)
Eling, Christopher
2017-02-01
Asymptotic spacetime symmetries have been conjectured to play an important role in quantum gravity. In this paper we study the breaking of asymptotic symmetries associated with a null horizon boundary. In two-dimensions, these symmetries are reparametrizations of the time parameter on the horizon. We show how this horizon reparametrization symmetry is explicitly and spontaneously broken in dilaton gravity and construct an effective action for these pseudo-Goldstone modes using the on-shell gravitational action for a null boundary. The variation of this action yields the horizon constraint equation. This action is invariant under a 2 parameter subgroup of SL(2) transformations, whose Noether charges we interpret via the membrane paradigm. We place these results in the context of recent work on the near AdS2/ near CFT1 correspondence. In this setting the horizon action characterizes the infrared regime near the horizon and has a hydrodynamical sigma model form. We also discuss our construction in General Relativity. In the three-dimensional case there is a natural generalization of our results. However, in higher dimensions, the variation of the effective action only yields the Raychaudhuri equation for small perturbations of the horizon.
NASA Astrophysics Data System (ADS)
Shaing, K. C.; Lee, H.; Seol, J.; Aydemir, A. Y.
2015-08-01
Theory for neoclassical toroidal plasma viscosity in the low collisionality regime is extended to the vicinity of the magnetic axis in tokamaks with broken symmetry. The toroidal viscosity is induced by particles drifting off the perturbed magnetic surface under the influence of the symmetry breaking magnetic field. In the region away from the magnetic axis, the drift orbit dynamics is governed by the bounce averaged drift kinetic equation in the low collisionality regimes. In the vicinity of the magnetic axis, it is the drift kinetic equation, averaged over the trapped particle orbits, i.e., potato orbits, that governs the drift dynamics. The orbit averaged drift kinetic equation is derived when collision frequency is low enough for trapped particles to complete their potato trajectories. The resultant equation is solved in the 1 /ν regime to obtain transport fluxes and, thus, toroidal plasma viscosity through flux-force relation. Here, ν is the collision frequency. The viscosity does not vanish on the magnetic axis, and has the same scalings as that in the region away from magnetic axis, except that the fraction of bananas is replaced by the fraction of potatoes. It also has a weak radial dependence. Modeling of plasma flow velocity V for the case where the magnetic surfaces are broken is also discussed.
Skyrmions in quasi-2D chiral magnets with broken bulk and surface inversion symmetry
NASA Astrophysics Data System (ADS)
Rowland, James; Banerjee, Sumilan; Randeria, Mohit
2015-03-01
Most theoretical studies of skyrmions have focused on chiral magnets with broken bulk inversion symmetry, stabilized by easy-axis anisotropy. Recently, we considered 2D systems with broken surface inversion and showed that skyrmion crystals are more stable than in 3D, pointing out the importance of easy-plane anisotropy. In the present work we investigate quasi-2D systems which break both bulk and surface inversion symmetry. The Landau-Ginzburg free energy functional thus contains two Dzyloshinskii-Moriya terms of strength DD and DR arising from Dresselhaus and Rashba spin-orbit coupling respectively. We trace the evolution of the phase diagram as DD /DR is varied, and find that skyrmions are increasingly destabilized with respect to the cone phase as DD increases relative to DR. We find an evolution from vortex-like skyrmions in the pure Dresselhaus limit to hedgehog-like skyrmions in the pure Rashba limit. We discuss the relevance of these results to existing experiments and the prospects of tuning the ratio of Dresselhaus and Rashba spin-orbit coupling via film thickness and strain. Supported by NSF DMR-1410364 (J.R. and M.R.) and DOE-BES DE-SC0005035 (S.B.)
NASA Astrophysics Data System (ADS)
Ye, Jinwu
2005-03-01
We study the interlayer coherent incompressible phase in trilayer quantum Hall systems (TLQH) at total filling factor νT=1 from three approaches: Mutual composite fermion (MCF), composite boson (CB), and wave function approach. Just like in bilayer quantum Hall system, CB approach is superior than MCF approach in studying TLQH with broken symmetry. The Hall and Hall drag resistivities are found to be quantized at h/e2 . Two neutral gapless modes with linear dispersion relations are identified and the ratio of the two velocities is close to 3 . The excitation spectra are classified into two classes, charge neutral bosonic two-body bound states and charge ±1 fermionic three-body bound states. In general, there are two two-body Kosterlize-Thouless (KT) transition temperatures and one three-body KT transition. The charge ±1 three-body fermionic bound states may be the main dissipation source of transport measurements. The broken symmetry in terms of SU (3) algebra is studied. The structure of excitons and their flowing patterns are given. The coupling between the two Goldstone modes will lead to the broadening in the zero-bias peak in the interlayer correlated tunnelings of the TLQH. Several interesting features unique to TLQH are outlined. Limitations of the CB approach are also pointed out.
Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry
Ma, Eric Yue; Calvo, M. Reyes; Wang, Jing; Lian, Biao; Muhlbauer, Mathias; Brune, Christoph; Cui, Yong -Tao; Lai, Keji; Kundhikanjana, Worasom; Yang, Yongliang; Baenninger, Matthias; Konig, Markus; Ames, Christopher; Buhmann, Hartmut; Leubner, Philipp; Molenkamp, Laurens W.; Zhang, Shou -Cheng; Goldhaber-Gordon, David; Kelly, Michael A.; Shen, Zhi -Xun
2015-05-26
The realization of quantum spin Hall effect in HgTe quantum wells is considered a milestone in the discovery of topological insulators. Quantum spin Hall states are predicted to allow current flow at the edges of an insulating bulk, as demonstrated in various experiments. A key prediction yet to be experimentally verified is the breakdown of the edge conduction under broken time-reversal symmetry. Here we first establish a systematic framework for the magnetic field dependence of electrostatically gated quantum spin Hall devices. We then study edge conduction of an inverted quantum well device under broken time-reversal symmetry using microwave impedance microscopy, and compare our findings to a non-inverted device. At zero magnetic field, only the inverted device shows clear edge conduction in its local conductivity profile, consistent with theory. Surprisingly, the edge conduction persists up to 9 T with little change. Finally, this indicates physics beyond simple quantum spin Hall model, including material-specific properties and possibly many-body effects.
Unexpected edge conduction in mercury telluride quantum wells under broken time-reversal symmetry
Ma, Eric Yue; Calvo, M. Reyes; Wang, Jing; ...
2015-05-26
The realization of quantum spin Hall effect in HgTe quantum wells is considered a milestone in the discovery of topological insulators. Quantum spin Hall states are predicted to allow current flow at the edges of an insulating bulk, as demonstrated in various experiments. A key prediction yet to be experimentally verified is the breakdown of the edge conduction under broken time-reversal symmetry. Here we first establish a systematic framework for the magnetic field dependence of electrostatically gated quantum spin Hall devices. We then study edge conduction of an inverted quantum well device under broken time-reversal symmetry using microwave impedance microscopy,more » and compare our findings to a non-inverted device. At zero magnetic field, only the inverted device shows clear edge conduction in its local conductivity profile, consistent with theory. Surprisingly, the edge conduction persists up to 9 T with little change. Finally, this indicates physics beyond simple quantum spin Hall model, including material-specific properties and possibly many-body effects.« less
Proton Stability in Grand Unified Theories and Discrete Gauge Symmetries
Mohapatra, R. N.
2008-05-13
Most supersymmetric grand unified theories face the problem of rapid proton decay coming either from R-parity violating interactions and/or from Planck scale induced R-parity conserving operators, possibly induced by non-perturbative Planck scale effects such as black holes or wormholes. In this talk, I argue in favor of the possibility that a natural way to resolve this problem is to assume that there are new discrete or continuous gauge symmetries accompanying these theories that resolve these problems while at the same time allowing enough flexibility to have a viable model. I discuss this for left-right and SO(10) theories and discuss the profound impact such considerations have on the construction of realistic GUT models. I then discuss a recently proposed SO(10) model which has only apparently string inspired multiplets and has enough structure to be a realistic model.
Quantum Imaging of Interaction-Induced Spontaneous Broken-Symmetry Phases in Molecular Graphene
NASA Astrophysics Data System (ADS)
Rastawicki, Dominik; Sun, Yan; Liu, Yang; Chen, Yi-Ting; Manoharan, Hari C.
We present a survey of quantum states with interaction-induced broken symmetries observed in molecular graphene, assembled with atomic manipulation. These materials are assembled with atomic precision by patterning the Cu(111) two-dimensional electron gas surface state by single molecules; the molecules function as local potentials which form a coherently coupled system of electron quantum dots in a honeycomb lattice embedding massless Dirac fermions and tunable graphene properties. By crafting different local molecular arrangements together with varying lattice constants, we are able to probe a large parameter space of the strength of the intersite hopping parameter (bond strength), the doping level, and the interaction strength. The assembled nanomaterials are probed through STM/STS measurement, differential conductance maps, and quasiparticle interference with Fourier-transform STS. We observe both spontaneous nematic states and sublattice symmetry breaking in molecular graphene at very low band filling factors, and a nematic state in graphene variants where kinetic energy is effectively quenched. We show it is possible to modify and enhance the symmetry breaking effects by controlling certain boundary conditions and lattice geometry.
Zhang, Zhiwang; Wei, Qi; Cheng, Ying; Zhang, Ting; Wu, Dajian; Liu, Xiaojun
2017-02-24
The discovery of topological acoustics has revolutionized fundamental concepts of sound propagation, giving rise to strikingly unconventional acoustic edge modes immune to scattering. Because of the spinless nature of sound, the "spinlike" degree of freedom crucial to topological states in acoustic systems is commonly realized with circulating background flow or preset coupled resonator ring waveguides, which drastically increases the engineering complexity. Here we realize the acoustic pseudospin multipolar states in a simple flow-free symmetry-broken metamaterial lattice, where the clockwise (anticlockwise) sound propagation within each metamolecule emulates pseudospin down (pseudospin up). We demonstrate that tuning the strength of intermolecular coupling by simply contracting or expanding the metamolecule can induce the band inversion effect between the pseudospin dipole and quadrupole, which leads to a topological phase transition. Topologically protected edge states and reconfigurable topological one-way transmission for sound are further demonstrated. These results provide diverse routes to construct novel acoustic topological insulators with versatile applications.
Magnetic Fano resonances by design in symmetry broken THz meta-foils
NASA Astrophysics Data System (ADS)
Wu, Jianfeng; Moser, Herbert O.; Li, Rujiang; Yang, Yihao; Jing, Liqiao; Chen, Hongsheng; Breese, Mark B. H.
2017-02-01
Magnetic Fano resonances in there-dimensional symmetry broken meta-foils at THz frequencies are theoretically and experimentally studied. Sharp Fano resonances occur due to the interference between different resonances and can be designed by choosing geometric parameters of the meta-foil. At the Fano resonances, the meta-foil supports antisymmetric modes, whereas, at the main resonance, only a symmetric mode exists. The meta-foil is left-handed at the Fano resonances and shows sharp peaks of the real part of the refractive index in transmission with small effective losses opening a way to very sensitive high-speed sensing of dielectric changes in the surrounding media and of mechanical configuration.
Magnetic Fano resonances by design in symmetry broken THz meta-foils
Wu, Jianfeng; Moser, Herbert O.; Li, Rujiang; Yang, Yihao; Jing, Liqiao; Chen, Hongsheng; Breese, Mark B. H.
2017-01-01
Magnetic Fano resonances in there-dimensional symmetry broken meta-foils at THz frequencies are theoretically and experimentally studied. Sharp Fano resonances occur due to the interference between different resonances and can be designed by choosing geometric parameters of the meta-foil. At the Fano resonances, the meta-foil supports antisymmetric modes, whereas, at the main resonance, only a symmetric mode exists. The meta-foil is left-handed at the Fano resonances and shows sharp peaks of the real part of the refractive index in transmission with small effective losses opening a way to very sensitive high-speed sensing of dielectric changes in the surrounding media and of mechanical configuration. PMID:28150797
Broken time reversal symmetry states in superconductors using the ultrafast pump-probe method
NASA Astrophysics Data System (ADS)
Setty, Chandan; Hu, Jiangping
2015-03-01
The excitation of vibrational modes by ultrafast optical pulses can be a useful probe of the electronic ground state in a solid through the electron-phonon interactions. In this work, we show that the phase of the oscillations of reflectivity/transmissivity as a function of the delay time can contain signatures of broken time reversal symmetry (BTRS) in the superconducting ground state. To illustrate this, we consider a simple Hamiltonian consisting of a two band electronic part and a phononic part; additionally, we include terms which couple electrons to phonons and light. In the absence of dissipation, we show that on entry into the BTRS superconducting state, the phase of the reflectivity oscillations deviates from the normal state values of +/- π/2 in a continuous fashion. We will also comment on the effects of dissipation and the dependence of our result on the opacity of the superconductor.
NASA Astrophysics Data System (ADS)
Zhang, Zhiwang; Wei, Qi; Cheng, Ying; Zhang, Ting; Wu, Dajian; Liu, Xiaojun
2017-02-01
The discovery of topological acoustics has revolutionized fundamental concepts of sound propagation, giving rise to strikingly unconventional acoustic edge modes immune to scattering. Because of the spinless nature of sound, the "spinlike" degree of freedom crucial to topological states in acoustic systems is commonly realized with circulating background flow or preset coupled resonator ring waveguides, which drastically increases the engineering complexity. Here we realize the acoustic pseudospin multipolar states in a simple flow-free symmetry-broken metamaterial lattice, where the clockwise (anticlockwise) sound propagation within each metamolecule emulates pseudospin down (pseudospin up). We demonstrate that tuning the strength of intermolecular coupling by simply contracting or expanding the metamolecule can induce the band inversion effect between the pseudospin dipole and quadrupole, which leads to a topological phase transition. Topologically protected edge states and reconfigurable topological one-way transmission for sound are further demonstrated. These results provide diverse routes to construct novel acoustic topological insulators with versatile applications.
Kessler, Eva M. V.; Schmitt, Sebastian; Wüllen, Christoph van
2013-11-14
The broken symmetry approach to the calculation of zero field splittings (or magnetic anisotropies) of multinuclear transition metal complexes is further developed. A procedure is suggested how to extract spin Hamiltonian parameters for anisotropic exchange from a set of broken symmetry density functional calculations. For isotropic exchange coupling constants J{sub ij}, the established procedure is retrieved, and anisotropic (or pseudodipolar) exchange coupling tensors D{sub ij} are obtained analogously. This procedure only yields the sum of the individual single-ion zero field splitting tensors D{sub i}. Therefore, a procedure based on localized orbitals has been developed to extract the individual single-ion contributions. With spin Hamiltonian parameters at hand, the zero field splittings of the individual spin multiplets are calculated by an exact diagonalization of the isotropic part, followed by a spin projection done numerically. The method is applied to the binuclear cation [LCr(OH){sub 3}CrL]{sup 3+} (L = 1,4,7-trimethyl-1,4,7-triazanonane) for which experimental zero field splittings for all low-energy spin states are known, and to the single-molecule magnet [Fe{sub 4}(CH{sub 3}C(CH{sub 2}O){sub 3}){sub 2}(dpm){sub 6}] (Hdpm = 2,2,6,6-tetramethylheptane-3,5-dione). In both these 3d compounds, the single-ion tensors mainly come from the spin-orbit interaction. Anisotropic exchange is dominated by the spin-dipolar interaction only for the chromium compound. Despite the rather small isotropic exchange couplings in the iron compound, spin-orbit and spin-dipolar contributions to anisotropic exchange are of similar size here.
Unification of gauge, family, and flavor symmetries illustrated in gauged SU(12) models
Albright, Carl H.; Feger, Robert P.; Kephart, Thomas W.
2016-04-25
In this study, to explain quark and lepton masses and mixing angles, one has to extend the standard model, and the usual practice is to put the quarks and leptons into irreducible representations of discrete groups. We argue that discrete flavor symmetries (and their concomitant problems) can be avoided if we extend the gauge group. In the framework of SU(12) we give explicit examples of models having varying degrees of predictability obtained by scanning over groups and representations and identifying cases with operators contributing to mass and mixing matrices that need little fine- tuning of prefactors. Fitting with quark andmore » lepton masses run to the GUT scale and known mixing angles allows us to make predictions for the neutrino masses and hierarchy, the octant of the atmospheric mixing angle, leptonic CP violation, Majorana phases, and the effective mass observed in neutrinoless double beta decay.« less
Unification of gauge, family, and flavor symmetries illustrated in gauged SU(12) models
Albright, Carl H.; Feger, Robert P.; Kephart, Thomas W.
2016-04-25
In this study, to explain quark and lepton masses and mixing angles, one has to extend the standard model, and the usual practice is to put the quarks and leptons into irreducible representations of discrete groups. We argue that discrete flavor symmetries (and their concomitant problems) can be avoided if we extend the gauge group. In the framework of SU(12) we give explicit examples of models having varying degrees of predictability obtained by scanning over groups and representations and identifying cases with operators contributing to mass and mixing matrices that need little fine- tuning of prefactors. Fitting with quark and lepton masses run to the GUT scale and known mixing angles allows us to make predictions for the neutrino masses and hierarchy, the octant of the atmospheric mixing angle, leptonic CP violation, Majorana phases, and the effective mass observed in neutrinoless double beta decay.
Toward electroweak scale cold dark matter with local dark gauge symmetry and beyond the DM EFT
NASA Astrophysics Data System (ADS)
Ko, Pyungwon
2016-06-01
In this talk, I describe a class of electroweak (EW) scale dark matter (DM) models where its stability or longevity are the results of underlying dark gauge symmetries: stable due to unbroken local dark gauge symmetry or topology, or long-lived due to the accidental global symmetry of dark gauge theories. Compared with the usual phenomenological dark matter models (including DM EFT or simplified DM models), DM models with local dark gauge symmetries include dark gauge bosons, dark Higgs bosons and sometimes excited dark matter. And dynamics among these fields are completely fixed by local gauge principle. The idea of singlet portals including the Higgs portal can thermalize these hidden sector dark matter very efficiently, so that these DM could be easily thermal DM. I also discuss the limitation of the usual DM effective field theory or simplified DM models without the full SM gauge symmetry, and emphasize the importance of the full SM gauge symmetry and renormalizability especially for collider searches for DM.
Projected Entangled Pair States with non-Abelian gauge symmetries: An SU(2) study
NASA Astrophysics Data System (ADS)
Zohar, Erez; Wahl, Thorsten B.; Burrello, Michele; Cirac, J. Ignacio
2016-11-01
Over the last years, Projected Entangled Pair States have demonstrated great power for the study of many body systems, as they naturally describe ground states of gapped many body Hamiltonians, and suggest a constructive way to encode and classify their symmetries. The PEPS study is not only limited to global symmetries, but has also been extended and applied for local symmetries, allowing to use them for the description of states in lattice gauge theories. In this paper we discuss PEPS with a local, SU(2) gauge symmetry, and demonstrate the use of PEPS features and techniques for the study of a simple family of many body states with a non-Abelian gauge symmetry. We present, in particular, the construction of fermionic PEPS able to describe both two-color fermionic matter and the degrees of freedom of an SU(2) gauge field with a suitable truncation.
Broken symmetry states in bilayer graphene in electric and in-plane magnetic fields
NASA Astrophysics Data System (ADS)
Jia, Junji; Pyatkovskiy, P. K.; Gorbar, E. V.; Gusynin, V. P.
2017-01-01
Broken symmetry states in bilayer graphene in perpendicular electric E⊥ and in-plane magnetic B∥ fields are studied in the presence of the dynamically screened long-range Coulomb interaction and the symmetry-breaking contact four-fermion interactions. The integral gap equations are solved numerically, and it is shown that the momentum dependence of gaps is essential: It diminishes by an order of magnitude the gaps compared to the case of momentum-independent approximation, and the obtained gap magnitudes are found to agree well with existing experimental values. We derived a phase diagram of bilayer graphene at the neutrality point in the plane (B∥,E⊥) showing that the (canted) layer antiferromagnetic (LAF) state remains a stable ground state of the system at large B∥. On the other hand, while the LAF phase is realized at small values of E⊥, the quantum valley Hall (QVH) phase is the ground state of the system at values E⊥>Ec r(B∥) , where a critical value Ec r(B∥) increases with in-plane magnetic field B||.
Bogoliubov Fermi Surfaces in Superconductors with Broken Time-Reversal Symmetry
NASA Astrophysics Data System (ADS)
Agterberg, D. F.; Brydon, P. M. R.; Timm, C.
2017-03-01
It is commonly believed that, in the absence of disorder or an external magnetic field, there are three possible types of superconducting excitation gaps: The gap is nodeless, it has point nodes, or it has line nodes. Here, we show that, for an even-parity nodal superconducting state which spontaneously breaks time-reversal symmetry, the low-energy excitation spectrum generally does not belong to any of these categories; instead, it has extended Bogoliubov Fermi surfaces. These Fermi surfaces can be visualized as two-dimensional surfaces generated by "inflating" point or line nodes into spheroids or tori, respectively. These inflated nodes are topologically protected from being gapped by a Z2 invariant, which we give in terms of a Pfaffian. We also show that superconducting states possessing these Fermi surfaces can be energetically stable. A crucial ingredient in our theory is that more than one band is involved in the pairing; since all candidate materials for even-parity superconductivity with broken time-reversal symmetry are multiband systems, we expect these Z2-protected Fermi surfaces to be ubiquitous.
Criterion for stability of Goldstone modes and Fermi liquid behavior in a metal with broken symmetry
Watanabe, Haruki; Vishwanath, Ashvin
2014-01-01
There are few general physical principles that protect the low-energy excitations of a quantum phase. Of these, Goldstone’s theorem and Landau–Fermi liquid theory are the most relevant to solids. We investigate the stability of the resulting gapless excitations—Nambu–Goldstone bosons (NGBs) and Landau quasiparticles—when coupled to one another, which is of direct relevance to metals with a broken continuous symmetry. Typically, the coupling between NGBs and Landau quasiparticles vanishes at low energies, leaving the gapless modes unaffected. If, however, the low-energy coupling is nonvanishing, non-Fermi liquid behavior and overdamped bosons are expected. Here we prove a general criterion that specifies when the coupling is nonvanishing. It is satisfied by the case of a nematic Fermi fluid, consistent with earlier microscopic calculations. In addition, the criterion identifies a new kind of symmetry breaking—of magnetic translations—where nonvanishing couplings should arise, opening a previously unidentified route to realizing non-Fermi liquid phases. PMID:25349386
Modulation of Fano resonances in symmetry-broken gold-SiO2-gold nanotube dimers
NASA Astrophysics Data System (ADS)
Wu, DaJian; Yu, HaiQun; Jiang, ShuMin; Wu, XueWei; Liu, XiaoJun
2014-06-01
Fano resonances in the symmetry-broken gold-SiO2-gold (BGSG) nanotubes and the associated dimers have been investigated based on the finite element method. In the BGSG nanotube, the symmetry breaking induced the interactions of the inner gold core and outer gold nanoshell plasmons of all multipolar orders and hence the red-shifts of the plasmon resonance modes and the enhanced quadrupole mode peaks were observed. The interference of the quadrupole mode peak with the subradiant dipole mode caused a Fano-dip in the scattering spectrum. By increasing the core offset-value in the BGSG nanotube, the Fano dip with low energy showed a red-shift and became deeper. Unexpectedly the plasmon coupling between a GSG nanotube and a BGSG nanotube can lead to two strong Fano dips in the scattering spectra of the dimer. It was further noted that the thin side of the BGSG nanotube located at two sides of the dimer gap can lead to the strong near-field coupling between two BGSG nanotubes and hence a deeper and broader Fano dip.
van Wüllen, Christoph
2009-10-29
Antiferromagnetic coupling in multinuclear transition metal complexes usually leads to electronic ground states that cannot be described by a single Slater determinant and that are therefore difficult to describe by Kohn-Sham density functional methods. Density functional calculations in such cases are usually converged to broken symmetry solutions which break spin and, in many cases, also spatial symmetry. While a procedure exists to extract isotropic Heisenberg (exchange) coupling constants from such calculations, no such approach is yet established for the calculation of magnetic anisotropy energies or zero field splitting parameters. This work proposes such a procedure. The broken symmetry solutions are not only used to extract the exchange couplings but also single-ion D tensors which are then used to construct a (phenomenological) spin Hamiltonian, from which the magnetic anisotropy and the zero-field energy levels can be computed. The procedure is demonstrated for a bi- and a trinuclear Mn(III) model compound.
A Fresh Twist on The Electron Microscope: Probing Broken Symmetries at a New Level
NASA Astrophysics Data System (ADS)
Idrobo, Juan Carlos
The introduction of aberration-correction in scanning transmission electron microscopy (STEM) has allowed the realization of Richard Feynman's long sought dream, atom-by-atom structural and elemental identification of materials by simply looking ``at the thing.'' Until now, the goal of aberration-correction in STEM has been to produce the smallest possible electron probes, which essentially corresponds to a near constant phase across the probe. Phases increase the size of electron probes and result in images and spectra with a lower spatial resolution. In this talk, calculations will be presented showing that aberrations in lenses are intrinsic generators of angular momentum, and that phases introduced in atomic-size electron probes can actually be beneficial when studying the symmetry of materials. In particular, examples of mapping magnetic ordering of materials with atomic size electron probes will be shown. Magnetic dichroism is one of the new frontiers where aberration-correction STEM can have a significant impact, and reveal information that is physically out of reach in X-ray and neutron synchrotrons. Current and future limitations in the experiments and requirements to reveal the magnetic moment (orbital and spin), charge ordering, crystal field splitting, spin-orbit-coupling, optical dichroism, and other physical phenomena associated with broken symmetries will be discussed. This research was supported by the Center for Nanophase Materials Sciences (CNMS), which is sponsored at Oak Ridge National Laboratory by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. Collaborators: J. Rusz, J. Spiegelberg, M.A. McGuire, C.T. Symons, R.R. Vatsavai, C. Cantoni and A.R. Lupini.
Absence of the fifth force problem in a model with spontaneously broken dilatation symmetry
Guendelman, E.I. Kaganovich, A.B.
2008-04-15
A scale invariant model containing dilaton {phi} and dust (as a model of matter) is studied where the shift symmetry {phi} {yields} {phi} + const. is spontaneously broken at the classical level due to intrinsic features of the model. The dilaton to matter coupling 'constant'f appears to be dependent of the matter density. In normal conditions, i.e. when the matter energy density is many orders of magnitude larger than the dilaton contribution to the dark energy density, f becomes less than the ratio of the 'mass of the vacuum' in the volume occupied by the matter to the Planck mass. The model yields this kind of 'Archimedes law' without any especial (intended for this) choice of the underlying action and without fine tuning of the parameters. The model not only explains why all attempts to discover a scalar force correction to Newtonian gravity were unsuccessful so far but also predicts that in the near future there is no chance to detect such corrections in the astronomical measurements as well as in the specially designed fifth force experiments on intermediate, short (like millimeter) and even ultrashort (a few nanometer) ranges. This prediction is alternative to predictions of other known models.
Q kink of the nonlinear O(3) {sigma} model involving an explicitly broken symmetry
Loginov, A. Yu.
2011-05-15
The (1 + 1)-dimensional nonlinear O(3) {sigma} model involving an explicitly broken symmetry is considered. Sphalerons are known to exist in this model. These sphalerons are of a topological origin and are embedded kinks of the sine-Gordon model. In the case of a compact spatial manifold S{sup 1}, sine-Gordon multikinks exist in the model. It is shown that the model admits a nonstatic generalization of the sine-Gordon kink/multikink, Q kink/multikink. Explicit expressions are obtained for the dependence of the Q kink energy and charge on the phase frequency of rotation. The Q kink is studied for stability, and expressions are obtained for the eigenfunctions and eigenfrequencies of the operator of quadratic fluctuations. It is shown that the Q kink is unstable over the entire admissible frequency range {omega} Element-Of [-1, 1]. The one-loop quantum correction to the static-kink mass is calculated, and the Q-kink zero mode is quantized. It is shown that, in a general static case, the field equations of the model are integrable in quadratures.
Intra- and interregional coregulation of opioid genes: broken symmetry in spinal circuits.
Kononenko, Olga; Galatenko, Vladimir; Andersson, Malin; Bazov, Igor; Watanabe, Hiroyuki; Zhou, Xing Wu; Iatsyshyna, Anna; Mityakina, Irina; Yakovleva, Tatiana; Sarkisyan, Daniil; Ponomarev, Igor; Krishtal, Oleg; Marklund, Niklas; Tonevitsky, Alex; Adkins, DeAnna L; Bakalkin, Georgy
2017-01-25
Regulation of the formation and rewiring of neural circuits by neuropeptides may require coordinated production of these signaling molecules and their receptors that may be established at the transcriptional level. Here, we address this hypothesis by comparing absolute expression levels of opioid peptides with their receptors, the largest neuropeptide family, and by characterizing coexpression (transcriptionally coordinated) patterns of these genes. We demonstrated that expression patterns of opioid genes highly correlate within and across functionally and anatomically different areas. Opioid peptide genes, compared with their receptor genes, are transcribed at much greater absolute levels, which suggests formation of a neuropeptide cloud that covers the receptor-expressed circuits. Surprisingly, we found that both expression levels and the proportion of opioid receptors are strongly lateralized in the spinal cord, interregional coexpression patterns are side-specific, and intraregional coexpression profiles are affected differently by left- and right-side unilateral body injury. We propose that opioid genes are regulated as interconnected components of the same molecular system distributed between distinct anatomic regions. The striking feature of this system is its asymmetric coexpression patterns, which suggest side-specific regulation of selective neural circuits by opioid neurohormones.-Kononenko, O., Galatenko, V., Andersson, M., Bazov, I., Watanabe, H., Zhou, X. W., Iatsyshyna, A., Mityakina, I., Yakovleva, T., Sarkisyan, D., Ponomarev, I., Krishtal, O., Marklund, N., Tonevitsky, A., Adkins, D. L., Bakalkin, G. Intra- and interregional coregulation of opioid genes: broken symmetry in spinal circuits.
Ferré, Nicolas; Guihéry, Nathalie; Malrieu, Jean-Paul
2015-06-14
This work re-examines the problem of the broken-symmetry Density-Functional Theory (DFT) solutions in diradical systems, in particular for the calculation of magnetic couplings. The Ms = 0 solution is not an eigenfunction of the S(2) spin operator and the evaluation of the singlet state energy requires a spin-decontamination. A popular approximation is provided by the so-called Yamaguchi formula, which operates using the expectation values of S(2) relative to both Ms = 1 and Ms =0 solutions. Referring to a previous decomposition of the magnetic coupling in terms of direct exchange, kinetic exchange and core polarization, it is shown that this expression will lead to unreliable values of the singlet-triplet energy gap when the spin polarization of the core orbitals becomes large. The here-proposed method of spin-decontamination is based on the Effective Hamiltonian Theory and uses the overlap between the two degenerate Ms = 0 solutions. An approximate and convenient formula, which uses the expectation values of S(2) of the Ms = 0 solutions before and after core polarization is proposed, which is free from the Yamaguchi's formula artefact, as illustrated on an organic diradical presenting a very high value of 〈S(2)〉 for the Ms = 0 solution, the antiferromagnetic coupling being due to the spin polarization mechanism.
Gauge symmetry and Virasoro algebra in quantum charged rigid membrane: A first order formalism
NASA Astrophysics Data System (ADS)
Paul, Biswajit
2013-02-01
The quantum charged rigid membrane model, which is a higher derivative theory, has been considered to explore its gauge symmetries using a recently developed first order formalism [R. Banerjee , J. High Energy Phys. 08 (2011) 085JHEPFG1029-8479]. Hamiltonian analysis has been performed and the gauge symmetry of the model is identified as reparametrization symmetry. First class constraints are shown to have a truncated Virasoro algebraic structure. An exact correspondence between the higher derivative theory and the first order formalism has been shown from the point of view of equations of motion.
Gauging the twisted Poincare symmetry as a noncommutative theory of gravitation
Chaichian, M.; Tureanu, A.; Oksanen, M.; Zet, G.
2009-02-15
Einstein's theory of general relativity was formulated as a gauge theory of Lorentz symmetry by Utiyama in 1956, while the Einstein-Cartan gravitational theory was formulated by Kibble in 1961 as the gauge theory of Poincare transformations. In this framework, we propose a formulation of the gravitational theory on canonical noncommutative space-time by covariantly gauging the twisted Poincare symmetry, in order to fulfil the requirement of covariance under the general coordinate transformations, an essential ingredient of the theory of general relativity. It appears that the twisted Poincare symmetry cannot be gauged by generalizing the Abelian twist to a covariant non-Abelian twist, nor by introducing a more general covariant twist element. The advantages of such a formulation as well as the related problems are discussed and possible ways out are outlined.
Kagome Chiral Spin Liquid as a Gauged U(1) Symmetry Protected Topological Phase.
He, Yin-Chen; Bhattacharjee, Subhro; Pollmann, Frank; Moessner, R
2015-12-31
While the existence of a chiral spin liquid (CSL) on a class of spin-1/2 kagome antiferromagnets is by now well established numerically, a controlled theoretical path from the lattice model leading to a low-energy topological field theory is still lacking. This we provide via an explicit construction starting from reformulating a microscopic model for a CSL as a lattice gauge theory and deriving the low-energy form of its continuum limit. A crucial ingredient is the realization that the bosonic spinons of the gauge theory exhibit a U(1) symmetry protected topological (SPT) phase, which upon promoting its U(1) global symmetry to a local gauge structure ("gauging"), yields the CSL. We suggest that such an explicit lattice-based construction involving gauging of a SPT phase can be applied more generally to understand topological spin liquids.
NASA Astrophysics Data System (ADS)
Fischetti, Massimo V.; Vandenberghe, William G.
2016-04-01
We show that the electron mobility in ideal, free-standing two-dimensional "buckled" crystals with broken horizontal mirror (σh) symmetry and Dirac-like dispersion (such as silicene and germanene) is dramatically affected by scattering with the acoustic flexural modes (ZA phonons). This is caused both by the broken σh symmetry and by the diverging number of long-wavelength ZA phonons, consistent with the Mermin-Wagner theorem. Non-σh-symmetric, "gapped" 2D crystals (such as semiconducting transition-metal dichalcogenides with a tetragonal crystal structure) are affected less severely by the broken σh symmetry, but equally seriously by the large population of the acoustic flexural modes. We speculate that reasonable long-wavelength cutoffs needed to stabilize the structure (finite sample size, grain size, wrinkles, defects) or the anharmonic coupling between flexural and in-plane acoustic modes (shown to be effective in mirror-symmetric crystals, like free-standing graphene) may not be sufficient to raise the electron mobility to satisfactory values. Additional effects (such as clamping and phonon stiffening by the substrate and/or gate insulator) may be required.
Wang, Y K; Dong, Z G; Zhai, Y
2012-08-01
We numerically investigate the antibonding magnetic resonance in a metamaterial composed of rings and plates, with a particular attention to the influence of broken structural symmetry on the Fano-type transmission spectrum as well as the resonant artificial permeability. From the simulation results, it is obvious that the antibonding magnetic resonance with strong magnetic-dipole coupling is responsible for the Fano-type profile, since an increase of the structural asymmetry extent to reduce the magnetic field confinement in one of the gaps will form, in contrary, a Lorentzian resonance dip. The dual excitation pathways, i.e., electric and magnetic resonances, at destructive interference are the underlying reason of the Fano-type transmission response. Additionally, the structural-asymmetry dependence of the artificial permeability shows that the broken symmetry can strongly modify the effective permeability due to the altering magnetic-dipole interactions. It is found that an anti-resonant curve of permeability versus frequency will be resulted in if significant symmetry-broken structure is introduced.
A short review on Noether’s theorems, gauge symmetries and boundary terms
NASA Astrophysics Data System (ADS)
Bañados, Max; Reyes, Ignacio
2016-06-01
This review is dedicated to some modern applications of the remarkable paper written in 1918 by E. Noether. On a single paper, Noether discovered the crucial relation between symmetries and conserved charges as well as the impact of gauge symmetries on the equations of motion. Almost a century has gone since the publication of this work and its applications have permeated modern physics. Our focus will be on some examples that have appeared recently in the literature. This review aims at students, not researchers. The main three topics discussed are (i) global symmetries and conserved charges (ii) local symmetries and gauge structure of a theory (iii) boundary conditions and algebra of asymptotic symmetries. All three topics are discussed through examples.
Weakly Isolated horizons: first order actions and gauge symmetries
NASA Astrophysics Data System (ADS)
Corichi, Alejandro; Reyes, Juan D.; Vukašinac, Tatjana
2017-04-01
The notion of Isolated Horizons has played an important role in gravitational physics, being useful from the characterization of the endpoint of black hole mergers to (quantum) black hole entropy. With an eye towards a canonical formulation we consider general relativity in terms of connection and vierbein variables and their corresponding first order actions. We focus on two main issues: (i) The role of the internal gauge freedom that exists, in the consistent formulations of the action principle, and (ii) the role that a 3 + 1 canonical decomposition has in the allowed internal gauge freedom. More concretely, we clarify in detail how the requirement of having well posed variational principles compatible with general weakly isolated horizons (WIHs) as internal boundaries does lead to a partial gauge fixing in the first order descriptions used previously in the literature. We consider the standard Hilbert–Palatini action together with the Holst extension (needed for a consistent 3 + 1 decomposition), with and without boundary terms at the horizon. We show in detail that, for the complete configuration space—with no gauge fixing—, while the Palatini action is differentiable without additional surface terms at the inner WIH boundary, the more general Holst action is not. The introduction of a surface term at the horizon—that renders the action for asymptotically flat configurations differentiable—does make the Holst action differentiable, but only if one restricts the configuration space and partially reduces the internal Lorentz gauge. For the second issue at hand, we show that upon performing a 3 + 1 decomposition and imposing the time gauge, there is a further gauge reduction of the Hamiltonian theory in terms of Ashtekar–Barbero variables to a U(1)-gauge theory on the horizon. We also extend our analysis to the more restricted boundary conditions of (strongly) isolated horizons as inner boundary. We show that even when
Albright, Carl H.; Rodejohann, Werner; /Heidelberg, Max Planck Inst.
2008-04-01
To address the issue of whether tri-bimaximal mixing (TBM) is a softly-broken hidden or an accidental symmetry, we adopt a model-independent analysis in which we perturb a neutrino mass matrix leading to TBM in the most general way but leave the three texture zeros of the diagonal charged lepton mass matrix unperturbed. We compare predictions for the perturbed neutrino TBM parameters with those obtained from typical SO(10) grand unified theories with a variety of flavor symmetries. Whereas SO(10) GUTs almost always predict a normal mass hierarchy for the light neutrinos, TBM has a priori no preference for neutrino masses. We find, in particular for the latter, that the value of |U{sub e3}| is very sensitive to the neutrino mass scale and ordering. Observation of |U{sub e3}|{sup 2} > 0.001 to 0.01 within the next few years would be incompatible with softly-broken TBM and a normal mass hierarchy and would suggest that the apparent TBM symmetry is an accidental symmetry instead. No such conclusions can be drawn for the inverted and quasi-degenerate hierarchy spectra.
Predicting the singlet vector channel in a partially broken gauge-Higgs theory
NASA Astrophysics Data System (ADS)
Maas, A.; Törek, P.
2017-01-01
We study a toy version of a grand-unified theory on the lattice: An S U (3 ) gauge theory, which experiences a Brout-Englert-Higgs effect due to a single Higgs field in the fundamental representation. This yields a perturbative breaking pattern S U (3 )→S U (2 ). We investigate the singlet vector channel, finding a nondegenerate and massive ground state. This is in contradistinction to the perturbative prediction of three massless and five massive vector states, even though the correlation functions of the gauge bosons exhibit a weak-coupling behavior, being almost tree-level-like. However, a combination of perturbation theory with the Fröhlich-Morchio-Strocchi mechanism, and thus passing to gauge-invariant perturbation theory, allows one to predict the physical spectrum in this channel.
Breaking an Abelian gauge symmetry near a black hole horizon
Gubser, Steven S.
2008-09-15
I argue that coupling the Abelian Higgs model to gravity plus a negative cosmological constant leads to black holes which spontaneously break the gauge invariance via a charged scalar condensate slightly outside their horizon. This suggests that black holes can superconduct.
Phenomenological Lagrangians, gauge models and branes
NASA Astrophysics Data System (ADS)
Zheltukhin, A. A.
2017-03-01
Phenomenological Lagrangians for physical systems with spontaneously broken symmetries are reformulated in terms of gauge field theory. Description of the Dirac p-branes in terms of the Yang-Mills- Cartan gauge multiplets interacting with gravity, is proved to be equivalent to their description as a closed dynamical system with the symmetry ISO(1, D - 1) spontaneously broken to ISO(1, p) × SO( D - p - 1).
Xia, Jing
2011-08-24
Polar Kerr effect in the high-Tc superconductor YBa{sub 2}Cu{sub 3}O{sub 6+x} was measured at zero magnetic field with high precision using a cyogenic Sagnac fiber interferometer. We observed non-zero Kerr rotations of order {approx} 1 {micro}rad appearing near the pseudogap temperature T*, and marking what appears to be a true phase transition. Anomalous magnetic behavior in magnetic-field training of the effect suggests that time reversal symmetry is already broken above room temperature.
NASA Astrophysics Data System (ADS)
Xiao, C. W.; Ozpineci, A.; Oset, E.
2015-10-01
Using a coupled channel unitary approach, combining the heavy quark spin symmetry and the dynamics of the local hidden gauge, we investigate the meson-meson interaction with hidden beauty. We obtain several new states of isospin I = 0: six bound states, and weakly bound six more possible states which depend on the influence of the coupled channel effects.
Dual-BRST symmetry: 6D Abelian 3-form gauge theory
NASA Astrophysics Data System (ADS)
Kumar, R.; Krishna, S.; Shukla, A.; Malik, R. P.
2012-04-01
Within the framework of the Becchi-Rouet-Stora-Tyutin (BRST) formalism, we demonstrate the existence of the novel off-shell nilpotent (anti-)dual-BRST symmetries in the context of a six (5+1)-dimensional (6D) free Abelian 3-form gauge theory. Under these local and continuous symmetry transformations, the total gauge-fixing term of the Lagrangian density remains invariant. This observation should be contrasted with the off-shell nilpotent (anti-)BRST symmetry transformations, under which, the total kinetic term of the theory remains invariant. The anticommutator of the above nilpotent (anti-)BRST and (anti-)dual-BRST transformations leads to the derivation of a bosonic symmetry in the theory. There exists a discrete symmetry transformation in the theory which provides a thread of connection between the nilpotent (anti-)BRST and (anti-)dual-BRST transformations. This theory is endowed with a ghost-scale symmetry, too. We discuss the algebra of these symmetry transformations and show that the structure of the algebra is reminiscent of the algebra of de Rham cohomological operators of differential geometry.
Matrix product operators for symmetry-protected topological phases: Gauging and edge theories
NASA Astrophysics Data System (ADS)
Williamson, Dominic J.; Bultinck, Nick; Mariën, Michael; Şahinoǧlu, Mehmet B.; Haegeman, Jutho; Verstraete, Frank
2016-11-01
Projected entangled pair states (PEPS) provide a natural ansatz for the ground states of gapped, local Hamiltonians in which global characteristics of a quantum state are encoded in properties of local tensors. We develop a framework to describe onsite symmetries, as occurring in systems exhibiting symmetry-protected topological (SPT) quantum order, in terms of virtual symmetries of the local tensors expressed as a set of matrix product operators (MPOs) labeled by distinct group elements. These MPOs describe the possibly anomalous symmetry of the edge theory, whose local degrees of freedom are concretely identified in a PEPS. A classification of SPT phases is obtained by studying the obstructions to continuously deforming one set of MPOs into another, recovering the results derived for fixed-point models [Chen et al., Phys. Rev. B 87, 155114 (2013), 10.1103/PhysRevB.87.155114]. Our formalism accommodates perturbations away from fixed-point models, opening the possibility of studying phase transitions between different SPT phases. We also demonstrate that applying the recently developed quantum state gauging procedure to a SPT PEPS yields a PEPS with topological order determined by the initial symmetry MPOs. The MPO framework thus unifies the different approaches to classifying SPT phases, via fixed-point models, boundary anomalies, or gauging the symmetry, into the single problem of classifying inequivalent sets of matrix product operator symmetries that are defined purely in terms of a PEPS.
Classification of static plane symmetric spacetime via Noether gauge symmetries
NASA Astrophysics Data System (ADS)
Jhangeer, Adil; Iftikhar, Nazish; Naz, Tayyaba
2016-07-01
In this paper, general static plane symmetric spacetime is classified with respect to Noether operators. For this purpose, Noether theorem is used which yields a set of linear partial differential equations (PDEs) with unknown radial functions A(r), B(r) and F(r). Further, these PDEs are solved by taking different possibilities of radial functions. In the first case, all radial functions are considered same, while two functions are taken proportional to each other in second case, which further discussed by taking four different relationships between A(r), B(r) and F(r). For all cases, different forms of unknown functions of radial factor r are reported for nontrivial Noether operators with non-zero gauge term. At the end, a list of conserved quantities for each Noether operator Tables 1-4 is presented.
Cost of seven-brane gauge symmetry in a quadrillion F-theory compactifications
NASA Astrophysics Data System (ADS)
Halverson, James; Tian, Jiahua
2017-01-01
We study seven-branes in O (1 015) four-dimensional F-theory compactifications where seven-brane moduli must be tuned in order to achieve non-Abelian gauge symmetry. The associated compact spaces B are the set of all smooth weak Fano toric threefolds. By a study of fine-star-regular triangulations of three-dimensional reflexive polytopes, the number of such spaces is estimated to be 5.8 ×1 014≲Nbases≲1.8 ×1 017 . Typically hundreds or thousands of moduli must be tuned to achieve symmetry for h11(B )<10 , but the average number drops sharply into the range O (25 )- O (200 ) as h11(B ) increases. For some low-rank groups, such as S U (2 ) and S U (3 ), there exist examples where only a few moduli must be tuned in order to achieve seven-brane gauge symmetry.
Universality of spontaneous chiral symmetry breaking in gauge theories
NASA Astrophysics Data System (ADS)
Gies, Holger; Wetterich, Christof
2004-01-01
We investigate one-flavor QCD with an additional chiral scalar field. For a large domain in the space of coupling constants, this model belongs to the same universality class as QCD, and the effects of the scalar become unobservable. This is connected to a “bound-state fixed point” of the renormalization flow for which all memory of the microscopic scalar interactions is lost. The QCD domain includes a microscopic scalar potential with minima at a nonzero field. On the other hand, for a scalar mass term m2 below a critical value m2c, the universality class is characterized by perturbative spontaneous chiral symmetry breaking which renders the quarks massive. Our renormalization group analysis shows how this universality class is continuously connected with the QCD universality class.
NASA Astrophysics Data System (ADS)
Barborini, Matteo; Guidoni, Leonardo
2016-09-01
The correct description of the ground state electronic and geometrical properties of multi-centre transition metal complexes necessitates of a high-level description of both dynamical and static correlation effects. In di-metallic complexes, the ground state low spin properties can be computed starting from single-determinants High-Spin (HS) and Broken Symmetry (BS) states by reconstructing an approximated low spin potential energy surface through the extended broken symmetry approach, based on the Heisenberg Hamiltonian. In the present work, we first apply this approach within the variational Monte Carlo method to tackle the geometry optimization of a Fe2S2(SH)42- model complex. To describe the HS and BS wavefunctions, we use a fully optimized unrestricted single determinant with a correlated Jastrow factor able to recover a large amount of dynamical correlation. We compared our results with those obtained by density functional theory and other multiconfigurational approaches, discussing the role of the nodal surface on the structural parameters.
Barborini, Matteo; Guidoni, Leonardo
2016-09-28
The correct description of the ground state electronic and geometrical properties of multi-centre transition metal complexes necessitates of a high-level description of both dynamical and static correlation effects. In di-metallic complexes, the ground state low spin properties can be computed starting from single-determinants High-Spin (HS) and Broken Symmetry (BS) states by reconstructing an approximated low spin potential energy surface through the extended broken symmetry approach, based on the Heisenberg Hamiltonian. In the present work, we first apply this approach within the variational Monte Carlo method to tackle the geometry optimization of a Fe2S2(SH)4(2-) model complex. To describe the HS and BS wavefunctions, we use a fully optimized unrestricted single determinant with a correlated Jastrow factor able to recover a large amount of dynamical correlation. We compared our results with those obtained by density functional theory and other multiconfigurational approaches, discussing the role of the nodal surface on the structural parameters.
Ovchinnikov, Igor V.
2011-05-15
Here, a scenario is proposed, according to which a generic self-organized critical (SOC) system can be looked upon as a Witten-type topological field theory (W-TFT) with spontaneously broken Becchi-Rouet-Stora-Tyutin (BRST) symmetry. One of the conditions for the SOC is the slow driving noise, which unambiguously suggests Stratonovich interpretation of the corresponding stochastic differential equation (SDE). This, in turn, necessitates the use of Parisi-Sourlas-Wu stochastic quantization procedure, which straightforwardly leads to a model with BRST-exact action, i.e., to a W-TFT. In the parameter space of the SDE, there must exist full-dimensional regions where the BRST symmetry is spontaneously broken by instantons, which in the context of SOC are essentially avalanches. In these regions, the avalanche-type SOC dynamics is liberated from overwise a rightful dynamics-less W-TFT, and a Goldstone mode of Fadeev-Popov ghosts exists. Goldstinos represent moduli of instantons (avalanches) and being gapless are responsible for the critical avalanche distribution in the low-energy, long-wavelength limit. The above arguments are robust against moderate variations of the SDE's parameters and the criticality is 'self-tuned'. The proposition of this paper suggests that the machinery of W-TFTs may find its applications in many different areas of modern science studying various physical realizations of SOC. It also suggests that there may in principle exist a connection between some SOC's and the concept of topological quantum computing.
Weyl gauge-vector and complex dilaton scalar for conformal symmetry and its breaking
NASA Astrophysics Data System (ADS)
Ohanian, Hans C.
2016-03-01
Instead of the scalar "dilaton" field that is usually adopted to construct conformally invariant Lagrangians for gravitation, we here propose a hybrid construction, involving both a complex dilaton scalar and a Weyl gauge-vector, in accord with Weyl's original concept of a non-Riemannian conformal geometry with a transport law for length and time intervals, for which this gauge vector is required. Such a hybrid construction permits us to avoid the wrong sign of the dilaton kinetic term (the ghost problem) that afflicts the usual construction. The introduction of a Weyl gauge-vector and its interaction with the dilaton also has the collateral benefit of providing an explicit mechanism for spontaneous breaking of the conformal symmetry, whereby the dilaton and the Weyl gauge-vector acquire masses somewhat smaller than {m}_{P} by the Coleman-Weinberg mechanism. Conformal symmetry breaking is assumed to precede inflation, which occurs later by a separate GUT or electroweak symmetry breaking, as in inflationary models based on the Higgs boson.
Novel symmetries in Weyl-invariant gravity with massive gauge field
NASA Astrophysics Data System (ADS)
Abhinav, K.; Shukla, A.; Panigrahi, P. K.
2016-11-01
The background field method is used to linearize the Weyl-invariant scalar-tensor gravity, coupled with a Stückelberg field. For a generic background metric, this action is found not to be invariant, under both a diffeomorphism and generalized Weyl symmetry, the latter being a combination of gauge and Weyl transformations. Interestingly, the quadratic Lagrangian, emerging from a background of Minkowski metric, respects both transformations independently. The Becchi-Rouet-Stora-Tyutin symmetry of scalar-tensor gravity coupled with a Stückelberg-like massive gauge particle, possessing a diffeomorphism and generalized Weyl symmetry, reveals that in both cases negative-norm states with unphysical degrees of freedom do exist. We then show that, by combining diffeomorphism and generalized Weyl symmetries, all the ghost states decouple, thereby removing the unphysical redundancies of the theory. During this process, the scalar field does not represent any dynamic mode, yet modifies the usual harmonic gauge condition through non-minimal coupling with gravity.
BPS states in type IIB SUGRA with SO(4) × SO(2)gauged symmetry
NASA Astrophysics Data System (ADS)
Donos, Aristomenis
2007-05-01
We present an extension of our construction (hep-th/0606199) exhibiting SO(4) × SO(2) symmetry. We extend the previously presented ansatz by introducing a U(1) gauge field. The presence of the gauge field allows for more general values of the Killing spinor U(1) charge. One more time we identify a four dimensional Kahler structure and a Monge-Ampere type of equation parametrized by the U(1) Killing spinor charge. In addition we identify 2 scalars that parametrize the supersymmetric solutions, one of which is the Kahler potential.
A global inversion-symmetry-broken phase inside the pseudogap region of YBa2Cu3Oy
NASA Astrophysics Data System (ADS)
Zhao, L.; Belvin, C. A.; Liang, R.; Bonn, D. A.; Hardy, W. N.; Armitage, N. P.; Hsieh, D.
2016-11-01
The phase diagram of cuprate high-temperature superconductors features an enigmatic pseudogap region that is characterized by a partial suppression of low-energy electronic excitations. Polarized neutron diffraction, Nernst effect, terahertz polarimetry and ultrasound measurements on YBa2Cu3Oy suggest that the pseudogap onset below a temperature T* coincides with a bona fide thermodynamic phase transition that breaks time-reversal, four-fold rotation and mirror symmetries respectively. However, the full point group above and below T* has not been resolved and the fate of this transition as T* approaches the superconducting critical temperature Tc is poorly understood. Here we reveal the point group of YBa2Cu3Oy inside its pseudogap and neighbouring regions using high-sensitivity linear and second-harmonic optical anisotropy measurements. We show that spatial inversion and two-fold rotational symmetries are broken below T* while mirror symmetries perpendicular to the Cu-O plane are absent at all temperatures. This transition occurs over a wide doping range and persists inside the superconducting dome, with no detectable coupling to either charge ordering or superconductivity. These results suggest that the pseudogap region coincides with an odd-parity order that does not arise from a competing Fermi surface instability and exhibits a quantum phase transition inside the superconducting dome.
Enhanced symmetries of gauge theory and resolving the spectrum of local operators
NASA Astrophysics Data System (ADS)
Kimura, Yusuke; Ramgoolam, Sanjaye
2008-12-01
Enhanced global non-Abelian symmetries at zero coupling in Yang Mills theory play an important role in diagonalizing the two-point functions of multimatrix operators. Generalized Casimirs constructed from the iterated commutator action of these enhanced symmetries resolve all the multiplicity labels of the bases of matrix operators which diagonalize the two-point function. For the case of U(N) gauge theory with a single complex matrix in the adjoint of the gauge group we have a U(N)×4 global symmetry of the scaling operator at zero coupling. Different choices of commuting sets of Casimirs, for the case of a complex matrix, lead to the restricted Schur basis previously studied in connection with string excitations of giant gravitons and the Brauer basis studied in connection with brane-antibrane systems. More generally these remarks can be extended to the diagonalization for any global symmetry group G. Schur-Weyl duality plays a central role in connecting the enhanced symmetries and the diagonal bases.
Spatially-Hyperbolic Friedmann-Robertson-Walker Universe with Potentially Broken Z 2-Symmetry
NASA Astrophysics Data System (ADS)
Dariescu, Ciprian; Bodnarescu, Adrian; Dariescu, Marina-Aura
2016-09-01
For the Friedmann-Robertson-Walker (FRW) Universe with negative curvature, sustained by a spontaneous Z 2- symmetry breaking scalar field, depending on time alone, we have derived the Einstein-Gordon system of equations. For physically relevant cases, the matter-curvature system have been numerically analyzed.
Monopole operators and mirror symmetry in three-dimensional gauge theories
NASA Astrophysics Data System (ADS)
Borokhov, Vadim A.
Many gauge theories in three dimensions flow to interacting conformal field theories in the infrared. We define a new class of local operators in these conformal field theories that are not polynomial in the fundamental fields and create topological disorder. They can be regarded as higher-dimensional analogs of twist and winding-state operators in free 2-D CFTs. We call them monopole operators for reasons explained in the text. The importance of monopole operators is that in the Higgs phase, they create Abrikosov-Nielsen-Olesen vortices. We study properties of these operators in three-dimensional gauge theories using large Nf expansion. For non-supersymmetric gauge theories we show that monopole operators belong to representations of the conformal group whose primaries have dimension of order N f. We demonstrate that these monopole operators transform non-trivially under the flavor symmetry group. We also consider topology-changing operators in the infrared limits of N = 2 and N = 4 supersymmetric QED as well as N = 4 SU(2) gauge theory in three dimensions. Using large N f expansion and operator-state isomorphism of the resulting superconformal field theories, we construct monopole operators that are primaries of short representation of the superconformal algebra and compute their charges under the global symmetries. Predictions of three-dimensional mirror symmetry for the quantum numbers of these monopole operators are verified. Furthermore, we argue that some of our large-Nf results are exact. This implies, in particular, that certain monopole operators in N = 4 d = 3 SQED with Nf = 1 are free fields. This amounts to a proof of 3-D mirror symmetry in these special cases.
Song, Zhigang; Quhe, Ruge; Liu, Shunquan; Li, Yan; Feng, Ji; Yang, Yingchang; Lu, Jing; Yang, Jinbo
2015-09-11
In this Letter, a tunable valley polarization is investigated for honeycomb systems with broken inversion symmetry such as transition-metal dichalcogenide MX2 (M = Mo, W; X = S, Se) monolayers through elliptical pumping. Compared to circular pumping, elliptical pumping is a more universal and effective method to create coherent valley polarization. When two valleys of MX2 monolayers are doped or polarized, a novel anomalous Hall effect (called valley orbital magnetic moment Hall effect) is predicted. Valley orbital magnetic moment Hall effect can generate an orbital magnetic moment current without the accompaniment of a charge current, which opens a new avenue for exploration of valleytronics and orbitronics. Valley orbital magnetic moment Hall effect is expected to overshadow spin Hall effect and is tunable under elliptical pumping.
Symmetry-broken electronic structure and uniaxial Fermi surface nesting of untwinned CaFe2As2
NASA Astrophysics Data System (ADS)
Wang, Q.; Sun, Z.; Rotenberg, E.; Ronning, F.; Bauer, E. D.; Lin, H.; Markiewicz, R. S.; Lindroos, M.; Barbiellini, B.; Bansil, A.; Dessau, D. S.
2013-12-01
We used angle-resolved photoemission spectroscopy to make direct measurements of the electronic structure of the untwinned uniaxial state of CaFe2As2, the parent compound of an iron-based superconductor. The very small photon beam size, combined with the relatively large single-domain area on the crystal surfaces, allowed us to obtain the intrinsic symmetry-broken dispersions and Fermi surface (FS) geometries along the orthogonal Fe-Fe bond directions without any mechanical or magnetic detwinning processes. Comparing the optimized local density approximation calculations, an orbital-dependent band shifting is introduced to obtain better agreement, which is consistent with the development of orbital ordering. More interestingly, unidirectional straight and flat FS segments are observed near the zone center, which indicates the existence of a unidirectional charge density wave order. Our results indicate strong electronic anisotropy in CaFe2As2 and put strong constraints on theories for the iron-pnictide system.
Hexagonal pnictide SrPtAs; the role of spin-orbit interaction and locally broken inversion symmetry
NASA Astrophysics Data System (ADS)
Rhim, S. H.; Youn, S. J.; Fischer, M. H.; Agterberg, D. F.; Sigrist, M.; Weinert, M.; Freeman, A. J.
2012-02-01
The first hexagonal pnictide superconductor SrPtAs which consists of stacked PtAs layers has been studied using the FLAPW methodootnotetextWimmer, Krakauer, Weinert, and Freeman, Phys.Rev.B. 24, 864 (1981) and tight-binding methods. The single PtAs layer forms a honeycomb structure that exhibits: (1) locally broken inversion symmetry despite the presence of the global inversion center, and (2) strong spin-orbit interaction, for which physical consequences are nontrivial. Based on these findings, we predict significant enhancement of both the spin susceptibility and the paramagnetic limiting field with respect to the usual s wave superconductors. Further, we suggest an increase of TC by electron doping of a van Hove singularity.
Broken symmetry phase transition in solid p-H 2, o-D 2 and HD: crystal field effects
NASA Astrophysics Data System (ADS)
Freiman, Yu. A.; Hemley, R. J.; Jezowski, A.; Tretyak, S. M.
1999-04-01
We report the effect of the crystal field (CF) on the broken symmetry phase transition (BSP) in solid parahydrogen, orthodeuterium, and hydrogen deuteride. The CF was calculated taking into account a distortion from the ideal HCP structure. We find that, in addition to the molecular field generated by the coupling terms in the intermolecular potential, the Hamiltonian of the system contains a crystal-field term, originating from single-molecular terms in the intermolecular potential. Ignoring the CF is the main cause of the systematic underestimation of the transition pressure, characteristic of published theories of the BSP transition. The distortion of the lattice that gives rise to the negative CF in response to the applied pressure is in accord with the general Le Chatelier-Braun principle.
Hasenbusch, Martin
2016-03-01
The exchange or geometric cluster algorithm allows us to define a variance-reduced estimator of the connected two-point function in the presence of a broken Z(2)-symmetry. We present numerical tests for the improved Blume-Capel model on the simple-cubic lattice. We perform simulations for the critical isotherm, the low-temperature phase at vanishing external field, and, for comparison, also the high-temperature phase. For the connected two-point function, a substantial reduction of the variance can be obtained, allowing us to compute the correlation length ξ with high precision. Based on these results, estimates for various universal amplitude ratios that characterize the universality class of the three-dimensional Ising model are computed.
Song, Zhigang; Quhe, Ruge; Liu, Shunquan; Li, Yan; Feng, Ji; Yang, Yingchang; Lu, Jing; Yang, Jinbo
2015-01-01
In this Letter, a tunable valley polarization is investigated for honeycomb systems with broken inversion symmetry such as transition-metal dichalcogenide MX2 (M = Mo, W; X = S, Se) monolayers through elliptical pumping. Compared to circular pumping, elliptical pumping is a more universal and effective method to create coherent valley polarization. When two valleys of MX2 monolayers are doped or polarized, a novel anomalous Hall effect (called valley orbital magnetic moment Hall effect) is predicted. Valley orbital magnetic moment Hall effect can generate an orbital magnetic moment current without the accompaniment of a charge current, which opens a new avenue for exploration of valleytronics and orbitronics. Valley orbital magnetic moment Hall effect is expected to overshadow spin Hall effect and is tunable under elliptical pumping. PMID:26358835
Cresti, Alessandro; Ortmann, Frank; Louvet, Thibaud; Van Tuan, Dinh; Roche, Stephan
2013-05-10
The role of defect-induced zero-energy modes on charge transport in graphene is investigated using Kubo and Landauer transport calculations. By tuning the density of random distributions of monovacancies either equally populating the two sublattices or exclusively located on a single sublattice, all conduction regimes are covered from direct tunneling through evanescent modes to mesoscopic transport in bulk disordered graphene. Depending on the transport measurement geometry, defect density, and broken sublattice symmetry, the Dirac-point conductivity is either exceptionally robust against disorder (supermetallic state) or suppressed through a gap opening or by algebraic localization of zero-energy modes, whereas weak localization and the Anderson insulating regime are obtained for higher energies. These findings clarify the contribution of zero-energy modes to transport at the Dirac point, hitherto controversial.
Instability of one-step replica-symmetry-broken phase in satisfiability problems
NASA Astrophysics Data System (ADS)
Montanari, Andrea; Parisi, Giorgio; Ricci-Tersenghi, Federico
2004-02-01
We reconsider the one-step replica-symmetry-breaking (1RSB) solutions of two random combinatorial problems: k-XORSAT and k-SAT. We present a general method for establishing the stability of these solutions with respect to further steps of replica-symmetry breaking. Our approach extends the ideas of Montanari and Ricci-Tersenghi (2003 Eur. Phys. J. B 33 339) to more general combinatorial problems. It turns out that 1RSB is always unstable at sufficiently small clause density agr or high energy. In particular, the recent 1RSB solution to 3-SAT is unstable at zero energy for agr < agrm, with agrm ap 4.153. On the other hand, the SAT-UNSAT phase transition seems to be correctly described within 1RSB.
Electronic polymers and soft-matter-like broken symmetries in underdoped cuprates
Capati, M.; Caprara, S.; Di Castro, C.; Grilli, M.; Seibold, G.; Lorenzana, J.
2015-01-01
Empirical evidence in heavy fermion, pnictide and other systems suggests that unconventional superconductivity appears associated to some form of real-space electronic order. For the cuprates, despite several proposals, the emergence of order in the phase diagram between the commensurate antiferromagnetic state and the superconducting state is not well understood. Here we show that in this regime doped holes assemble in ‘electronic polymers'. Within a Monte Carlo study, we find that in clean systems by lowering the temperature the polymer melt condenses first in a smectic state and then in a Wigner crystal both with the addition of inversion symmetry breaking. Disorder blurs the positional order leaving a robust inversion symmetry breaking and a nematic order, accompanied by vector chiral spin order and with the persistence of a thermodynamic transition. Such electronic phases, whose properties are reminiscent of soft-matter physics, produce charge and spin responses in good accord with experiments. PMID:26144868
Exploring the zone of anisotropy and broken symmetries in DNA-mediated nanoparticle crystallization
Girard, Martin; Lin, Hai-Xin; Millan, Jaime A.; Olvera de la Cruz, Monica; Lee, Byeongdu; Mirkin, Chad A.
2016-01-01
In this work, we present a joint experimental and molecular dynamics simulations effort to understand and map the crystallization behavior of polyhedral nanoparticles assembled via the interaction of DNA surface ligands. In these systems, we systematically investigated the interplay between the effects of particle core (via the particle symmetry and particle size) and ligands (via the ligand length) on crystallization behavior. This investigation revealed rich phase diagrams, previously unobserved phase transitions in polyhedral crystallization behavior, and an unexpected symmetry breaking in the ligand distribution on a particle surface. To understand these results, we introduce the concept of a zone of anisotropy, or the portion of the phase space where the anisotropy of the particle is preserved in the crystallization behavior. Through comparison of the zone of anisotropy for each particle we develop a foundational roadmap to guide future investigations. PMID:27601636
NASA Astrophysics Data System (ADS)
Lu, Xiancong; Wu, Ziwen; Zhang, Wuhong; Chen, Lixiang
2014-05-01
The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved.
Lu, Xiancong; Wu, Ziwen; Zhang, Wuhong; Chen, Lixiang
2014-05-02
The law of angular momentum conservation is naturally linked to the rotational symmetry of the involved system. Here we demonstrate theoretically how to break the rotational symmetry of a uniaxial crystal via the electro-optic Pockels effect. By numerical method based on asymptotic expansion, we discover the 3D structure of polarization singularities in terms of C lines and L surfaces embedded in the emerging light. We visualize the controllable dynamics evolution of polarization singularities when undergoing the Pockels effect, which behaves just like the binary fission of a prokaryotic cell, i.e., the splitting of C points and fission of L lines are animated in analogy with the cleavage of nucleus and division of cytoplasm. We reveal the connection of polarization singularity dynamics with the accompanying generation of orbital angular momentum sidebands. It is unexpected that although the total angular momentum of light is not conserved, the total topological index of C points is conserved.
Influence of broken flavor and C and P symmetry on the quark propagator
NASA Astrophysics Data System (ADS)
Maas, Axel; Mian, Walid Ahmed
2017-02-01
Embedding QCD into the standard model breaks various symmetries of QCD explicitly, especially C and P . While these effects are usually perturbatively small, they can be amplified in extreme environments like merging neutron stars or by the interplay with new physics. To correctly treat these cases requires fully backcoupled calculations. To pave the way for later investigations of hadronic physics, we study the QCD quark propagator coupled to an explicit breaking. This substantially increases the tensor structure even for this simplest correlation function. To cope with the symmetry structure, and covering all possible quark masses, from the top quark mass to the chiral limit, we employ Dyson-Schwinger equations. While at weak breaking the qualitative effects have similar trends as in perturbation theory, even moderately strong breakings lead to qualitatively different effects, non-linearly amplified by the strong interactions.
A VMD Based, Nonet and SU(3) Symmetry Broken Model for Radiative Decays of Light Mesons
Benayoun, M.
2005-04-06
We present a VMD based model aiming to describe all radiative decays of light mesons. We show that the SU(3) breaking mechanism proposed by Bando, Kugo and Yamawaki (BKY), supplemented by nonet symmetry breaking in the pseudoscalar sector are sufficient to provide a nice description of all data, except the K*{sup {+-}} radiative width. It is also shown that nonet symmetry breaking has effects which cannot be disentangled from those produced by coupling of glue to the {eta}{prime} meson. Coupling of glue to {eta} is not found to be required by the data. Assuming the K*{sup {+-}} radiative width is indeed at its presently accepted value necessitates to supplement the BKY breaking in a way which finally preserves an equivalence statement between the VMD approach to radiative decays and the Wess-Zumino-Witten Lagrangian.
NASA Astrophysics Data System (ADS)
Zhao, Liu; Yu, Pengfei; Xu, Wei
2013-02-01
Shapere and Wilczek recently found some singular Lagrangian systems which spontaneously breaks time translation symmetry. The common feature of their models is that the energy functions are multi-valued in terms of the canonical phase space variables and the symmetry breaking ground states are all located at the brunching point singularities. By enlarging the phase space and making use of Dirac's theory on constrained Hamiltonian systems, we present the Hamiltonian description of some of the models discussed by Shapere and Wilczek and found that both the multi-valuedness and the brunching point singularities can be avoided, while the spontaneous breaking of time translation becomes more transparent. It is also shown that the breaking of time translation is always accompanied by the breaking of time reversal.
Noether’s second theorem and Ward identities for gauge symmetries
Avery, Steven G.; Schwab, Burkhard U. W.
2016-02-04
Recently, a number of new Ward identities for large gauge transformations and large diffeomorphisms have been discovered. Some of the identities are reinterpretations of previously known statements, while some appear to be genuinely new. We present and use Noether’s second theorem with the path integral as a powerful way of generating these kinds of Ward identities. We reintroduce Noether’s second theorem and discuss how to work with the physical remnant of gauge symmetry in gauge fixed systems. We illustrate our mechanism in Maxwell theory, Yang-Mills theory, p-form field theory, and Einstein-Hilbert gravity. We comment on multiple connections between Noether’s secondmore » theorem and known results in the recent literature. Finally, our approach suggests a novel point of view with important physical consequences.« less
Noether’s second theorem and Ward identities for gauge symmetries
Avery, Steven G.; Schwab, Burkhard U. W.
2016-02-04
Recently, a number of new Ward identities for large gauge transformations and large diffeomorphisms have been discovered. Some of the identities are reinterpretations of previously known statements, while some appear to be genuinely new. We present and use Noether’s second theorem with the path integral as a powerful way of generating these kinds of Ward identities. We reintroduce Noether’s second theorem and discuss how to work with the physical remnant of gauge symmetry in gauge fixed systems. We illustrate our mechanism in Maxwell theory, Yang-Mills theory, p-form field theory, and Einstein-Hilbert gravity. We comment on multiple connections between Noether’s second theorem and known results in the recent literature. Finally, our approach suggests a novel point of view with important physical consequences.
Triplets, Static SU(6), and Spontaneously Broken Chiral SU(3) Symmetry
DOE R&D Accomplishments Database
Nambu, Y.
1966-01-01
I would like to present here my view of the current problems of elementary particle theory. It is largely inspired by the recent successes of SU(3) and SU(6) symmetries, and more or less summarizes what I have been pursuing lately. For the details of individual problems I must refer to the original papers. However, what is emphasized here is not the details, but a coherent overall picture plus some speculations which cannot yet be formulated precisely.
Nilpotent Symmetries for Matter Fields in Non-Abelian Gauge Theory:
NASA Astrophysics Data System (ADS)
Malik, R. P.
In the framework of superfield approach to Becchi-Rouet-Stora-Tyutin (BRST) formalism, the derivation of the BRST and anti-BRST nilpotent symmetry transformations for the matter fields, present in any arbitrary interacting gauge theory, has been a long-standing problem. In our present investigation, the local, covariant, continuous and off-shell nilpotent (anti-)BRST symmetry transformations for the Dirac fields (ψ ,bar ψ ) are derived in the framework of the augmented superfield formulation where the four (3 + 1)-dimensional (4D) interacting non-Abelian gauge theory is considered on the six (4 + 2)-dimensional supermanifold parametrized by the four even space-time coordinates xμ and a couple of odd elements (θ and bar θ ) of the Grassmann algebra. The requirement of the invariance of the matter (super)currents and the horizontality condition on the (super)manifolds leads to the derivation of the nilpotent symmetries for the matter fields as well as the gauge and the (anti)ghost fields of the theory in the general scheme of augmented superfield formalism.
Observation of Quantum Spin Hall States in InAs/GaSb Bilayers under Broken Time-Reversal Symmetry
NASA Astrophysics Data System (ADS)
Du, Lingjie; Knez, Ivan; Sullivan, Gerard; Du, Rui-Rui
2014-03-01
Topological insulators (TIs) are a novel class of materials with nontrivial surface or edge states. Time-reversal symmetry (TRS) protected TIs are characterized by the Z2 topological invariant. The fate of the Z2 TIs under broken TRS is a fundamental question in understanding the physics of topological matter but remains largely unanswered. Here we show, a two-dimensional TI is realized in an inverted electron-hole bilayer engineered from InAs/GaSb semiconductors which retains robust helical liquid (HL) edge states under a strong magnetic field. Wide conductance plateaus of 2e2/h value are observed; they persist to 10T applied in-plane field before transitioning to a trivial semimetal. In a perpendicular field up to 35T, broken TRS leads to a spatial separation of the movers in Kramers pair and consequently the intra-pair backscattering phase space vanishes, i.e., the conductance increases from 2e2/h in strong fields manifesting chiral edge transport. We propose a phenomenological phases diagram, where inside the topological gap the HL transfers into a ``canned helical state'' driven by perpendicular fields. Our findings suggest that once established, the HL is remarkably resilient and only undergoes adiabatic deformation under TRS breaking. The work at Rice was supported by DOE, NSF, and Welch Foundation.
Dirac dark matter and b →s ℓ+ℓ- with U(1) gauge symmetry
NASA Astrophysics Data System (ADS)
Celis, Alejandro; Feng, Wan-Zhe; Vollmann, Martin
2017-02-01
We revisit the possibility of a Dirac fermion dark matter candidate in the light of current b →s ℓ+ℓ- anomalies by investigating a minimal extension of the Standard Model with a horizontal U(1 ) ' local symmetry. Dark matter stability is protected by a remnant Z2 symmetry arising after spontaneous symmetry breaking of U(1 ) '. The associated Z' gauge boson can accommodate current hints of new physics in b →s ℓ+ℓ- decays, and acts as a vector portal between dark matter and the visible sector. We find that the model is severely constrained by a combination of precision measurements at flavor factories, LHC searches for dilepton resonances, as well as direct and indirect dark matter searches. Despite this, viable regions of the parameter space accommodating the observed dark matter relic abundance and the b →s ℓ+ℓ-anomalies still persist for dark matter and Z ' masses in the TeV range.
Zero energy gauge fields and the phases of a gauge theory
Guendelman, E.I. )
1990-07-20
A new approach to the definition of the phases of a Poincare invariant gauge theory is developed. It is based on the role of gauge transformations that change the asymptotic value of the gauge fields from zero to a constant. In the context of theories without Higgs fields, this symmetry can be spontaneously broken when the gauge fields are massless particles, explicitly broken when the gauge fields develop a mass. Finally, the vacuum can be invariant under this transformation, this last case can be achieved when the theory has a violent infrared behavior, which in some theories can be connected to a confinement mechanism.
NASA Astrophysics Data System (ADS)
Ramaswamy, Sriram; Simha, R. Aditi
2006-09-01
This articles reviews briefly our recent theoretical results on order, fluctuations and flow in collections of self-driven particles, in suspension or on a solid surface. The theoretical approach we have developed applies not only to collections of organisms such as schools of fish or collectively swimming bacteria, but also to motor-microtubule extracts with ATP and, most surprisingly, to agitated monolayers of orientable granular particles. We contrast the behaviour of these active systems with that of thermal equilibrium systems with the same symmetry. As an illustration of the role of activity we show that active smectics in three dimensions show true long-range order, unlike their thermal equilibrium counterparts.
Ko, P.; Tang, Yong
2015-01-16
We show that hidden sector dark matter (DM) models with local dark gauge symmetries make a natural playground for the possible γ-ray excess from the galactic center (GC). We first discuss in detail the GC γ-ray excess in a scalar dark matter (DM) model with local Z{sub 3} symmetry which was recently proposed by the present authors. Within this model, scalar DM with mass 30–70 GeV is allowed due to the newly-opened (semi-)annihilation channels of a DM pair into dark Higgs ϕ and/or dark photon Z′ pair, and the γ-ray spectrum from the GC can be fit within this model. Then we argue that the GC gamma ray excess can be easily accommodated within hidden sector dark matter models where DM is stabilized by local gauge symmetries, due to the presence of dark Higgs (and also dark photon for Abelian dark gauge symmetry)
Ko, P.; Tang, Yong E-mail: ytang@kias.re.kr
2015-01-01
We show that hidden sector dark matter (DM) models with local dark gauge symmetries make a natural playground for the possible γ-ray excess from the galactic center (GC). We first discuss in detail the GC γ-ray excess in a scalar dark matter (DM) model with local Z{sub 3} symmetry which was recently proposed by the present authors. Within this model, scalar DM with mass 30–70 GeV is allowed due to the newly-opened (semi-)annihilation channels of a DM pair into dark Higgs φ and/or dark photon Z' pair, and the γ-ray spectrum from the GC can be fit within this model. Then we argue that the GC gamma ray excess can be easily accommodated within hidden sector dark matter models where DM is stabilized by local gauge symmetries, due to the presence of dark Higgs (and also dark photon for Abelian dark gauge symmetry)
Non-Abelian Gauge Symmetry in the Causal Epstein-Glaser Approach
NASA Astrophysics Data System (ADS)
Hurth, Tobias
Non-Abelian gauge symmetry in (3 + 1)-dimensional space-time is analyzed in the causal Epstein-Glaser framework. In this formalism, the technical details concerning the well-known UV and IR problem in quantum field theory are separated and reduced to well-defined problems, namely the causal splitting and the adiabatic switching of operator-valued distributions. Non-Abelian gauge invariance in perturbation theory is completely discussed in the well-defined Fock space of free asymptotic fields. The LSZ formalism is not used in this construction. The linear operator condition of asymptotic gauge invariance is sufficient for the unitarity of the S matrix in the physical subspace and the usual Slavnov-Taylor identities. We explicitly derive the most general specific coupling compatible with this condition. By analyzing only tree graphs in the second order of perturbation theory we show that the well-known Yang-Mills couplings with anticommuting ghosts are the only ones which are compatible with asymptotic gauge invariance. The required generalizations for linear gauges are given.
Entanglement in fermionic chains with finite-range coupling and broken symmetries
NASA Astrophysics Data System (ADS)
Ares, Filiberto; Esteve, José G.; Falceto, Fernando; de Queiroz, Amilcar R.
2015-10-01
We obtain a formula for the determinant of a block Toeplitz matrix associated with a quadratic fermionic chain with complex coupling. Such couplings break reflection symmetry and/or charge conjugation symmetry. We then apply this formula to compute the Rényi entropy of a partial observation to a subsystem consisting of contiguous sites in the limit of large size. The present work generalizes similar results due to Its, Jin, and Korepin [Fields Institute Communications, Universality and Renormalization, Vol. 50, p. 151, 2007] and Its, Mezzadri, and Mo [Commun. Math. Phys. 284, 117 (2008), 10.1007/s00220-008-0566-6]. A striking feature of our formula for the entanglement entropy is the appearance of a term scaling with the logarithm of the size. This logarithmic behavior originates from certain discontinuities in the symbol of the block Toeplitz matrix. Equipped with this formula we analyze the entanglement entropy of a Dzyaloshinski-Moriya spin chain and a Kitaev fermionic chain with long-range pairing.
Stacking-dependent interlayer coupling in trilayer MoS2 with broken inversion symmetry
Yan, Jiaxu; Wang, Xingli; Tay, Beng Kang; ...
2015-11-13
The stacking configuration in few-layer two-dimensional (2D) materials results in different structural symmetries and layer-to-layer interactions, and hence it provides a very useful parameter for tuning their electronic properties. For example, ABA-stacking trilayer graphene remains semimetallic similar to that of monolayer, while ABC-stacking is predicted to be a tunable band gap semiconductor under an external electric field. Such stacking dependence resulting from many-body interactions has recently been the focus of intense research activities. Here we demonstrate that few-layer MoS2 samples grown by chemical vapor deposition with different stacking configurations (AA, AB for bilayer; AAB, ABB, ABA, AAA for trilayer) exhibitmore » distinct coupling phenomena in both photoluminescence and Raman spectra. By means of ultralow-frequency (ULF) Raman spectroscopy, we demonstrate that the evolution of interlayer interaction with various stacking configurations correlates strongly with layer-breathing mode (LBM) vibrations. Our ab initio calculations reveal that the layer-dependent properties arise from both the spin–orbit coupling (SOC) and interlayer coupling in different structural symmetries. Lastly, such detailed understanding provides useful guidance for future spintronics fabrication using various stacked few-layer MoS2 blocks.« less
Broken rotational and translational symmetries in the pseudogap phase of cuprates
NASA Astrophysics Data System (ADS)
Taillefer, Louis
2011-03-01
A large in-plane anisotropy of the Nernst coefficient in YBCO is found to set in precisely at the pseudogap temperature T* throughout the doping phase diagram. This implies that the pseudogap phase is an electronic state that breaks the four-fold rotational symmetry of the copper-oxide planes. At a somewhat lower temperature, of order T* /2, the positive Hall and Seebeck coefficients of YBCO start dropping, and they reach large negative values at T = 0 , in the normal state accessed by applying high magnetic fields [2,3]. We interpret this in terms of an electron pocket forming in the Fermi surface of YBCO as a result of a Fermi-surface reconstruction caused by some order which breaks the translational symmetry of the lattice. Because very similar transport anomalies are observed in Eu-LSCO, where they coincide with the onset of stripe order, we infer that some form of stripe order is also at play in YBCO, and argue that the pseudogap phase is a precursor region of stripe (or spin-density-wave) fluctuations. In collaboration with F. Laliberte, N. Doiron-Leyraud, J. Chang, R. Daou, O. Cyr-Choiniere, D. LeBoeuf, B. Vignolle, C. Proust, I. Sheikin, L. Malone, K. Behnia, B. J. Ramshaw, R. Liang, D. A. Bonn, W. N. Hardy, S. Pyon, T. Takayama, Y. Tanaka, H. Takagi.
NASA Astrophysics Data System (ADS)
Kholodnyi, V. A.
2002-05-01
Although symmetries play a major role in physics, their use in finance is relatively new and, to the best of our knowledge, can be traced to 1995 when Kholodnyi introduced the beliefs-preferences gauge symmetry. One of the main outcomes of the beliefs-preferences gauge symmetry is that it allows for the valuation and dynamic replication of contingent claims in a general market environment, that is, in the case of a general, not necessarily diffusion Markov process for the prices of underlying securities. This valuation and dynamic replication is based on the novel ideas of symmetry in contrast to the standard approach which uses stochastic analysis. The practical applications of the beliefs-preferences gauge symmetry range from the detection of a new type of true arbitrage to the beliefs-preferences-independent valuation and dynamic replication of contingent claims in a general market environment.
Kim, Jihn E.
2007-09-01
It is known that the kinetic mixing of a photon and another U(1){sub ex} gauge boson can introduce millicharged particles. Millicharged particles f of mass 0.1 eV can explain the PVLAS experiment. I suggest a temperature dependent gauge symmetry breaking of U(1){sub ex} for this idea to be consistent with astrophysical and cosmological constraints.
Broken Replica Symmetry Bounds in the Mean Field Spin Glass Model
NASA Astrophysics Data System (ADS)
Guerra, Francesco
By using a simple interpolation argument, in previous work we have proven the existence of the thermodynamic limit, for mean field disordered models, including the Sherrington-Kirkpatrick model, and the Derrida p-spin model. Here we extend this argument in order to compare the limiting free energy with the expression given by the Parisi Ansatz, and including full spontaneous replica symmetry breaking. Our main result is that the quenched average of the free energy is bounded from below by the value given in the Parisi Ansatz, uniformly in the size of the system. Moreover, the difference between the two expressions is given in the form of a sum rule, extending our previous work on the comparison between the true free energy and its replica symmetric Sherrington-Kirkpatrick approximation. We give also a variational bound for the infinite volume limit of the ground state energy per site.
Asymmetric motion of bubble in nematic liquid crystal induced by symmetry-broken evaporation
NASA Astrophysics Data System (ADS)
Kim, Sung-Jo; Lev, Bohdan; Kim, Jong-Hyun
2016-07-01
The size of air bubbles in nematic liquid crystals can be continuously decreased through the absorption of air molecules into the host liquid crystal. A bubble and its accompanying hyperbolic hedgehog point defect undergo a continuous asymmetric motion, while the bubble decreases in size. In this study, a mechanism is proposed to theoretically explain both the motion of the air bubble and the point defect observed experimentally. Anisotropic evaporation of air molecules may occur because of the symmetry breaking of the director configuration near the point defect. The motion of the center of the air bubble to the hyperbolic hedgehog point defect is induced by the anisotropic force due to evaporation of air molecules and Stokes drag force.
NASA Astrophysics Data System (ADS)
Krowne, Clifford
2004-03-01
A recent finding has shown that a unixial bi-crystal shows negative refraction (NR) [1], a property in common with recent left-handed metamaterials examined for physics of focusing behavior and of field distributions [2], and field contouring effects in electronic structures [3]. This is a very interesting property related to energy wave front motion and has an analog in electron ballistic motion in a semiconductor heterostructure too. The property which yields NR, breaks field symmetry, and allows asymmetric distributions of electromagnetic fields in the cross-section in which heterostructure layering occurs when propagation is normal to this cross-section in a longitudinal direction. What is all the more remarkable is that individual heterostructure layers are not field symmetry breaking and do not lead to asymmetric field distributions. In fact when a single crystal is inserted in a guiding structure, nothing special happens. When heterostructure layering is constructive, successive layers could enhance the effect. We demonstrate here for the first time, using a model stripline structure to guide the wave, that a bi-crystal will indeed produce asymmetric rf electric and magnetic distributions. Calculations were done with an ab initio approach using an anisotropic Greens function which allows the physical properties of the uniaxial crystals to be treated via their tensors. The results have important implications for microwave devices which rely on asymmetric field distributions. One could envision wide application in monolithic integrated circuits in terms of devices utilizing both microwave and millimeter transmission as well as optical transmission using dielectric waveguiding structures. [1] Y. Zhang, B. Fluegel and A. Mascarenhas, Phys. Rev. Lett. 91, 157404 (Oct. 2003). [2] C. M. Krowne, Phys. Rev. Lett. 92, to be publ. (2004). [3] C. M. Krowne, IEEE Trans. Microwave Theory & Tech. 51, (Dec. 2003).
Hoffmann, Alexander; Herres-Pawlis, Sonja
2014-01-14
The singlet, open-shell singlet and triplet potential energy surfaces (PES) for the peroxo state of a catalytic functional tyrosinase model have been investigated by density functional theory calculations. The broken-symmetry solution exhibits considerable stabilisation over the whole PES but the importance of the triplet state is unravelled as well.
Conditions for the emergence of gauge bosons from spontaneous Lorentz symmetry breaking
NASA Astrophysics Data System (ADS)
Escobar, C. A.; Urrutia, L. F.
2015-07-01
The emergence of gauge particles (e.g., photons and gravitons) as Goldstone bosons arising from spontaneous symmetry breaking is an interesting hypothesis which would provide a dynamical setting for the gauge principle. We investigate this proposal in the framework of a general SO (N ) non-Abelian Nambu model (NANM), effectively providing spontaneous Lorentz symmetry breaking in terms of the corresponding Goldstone bosons. Using a nonperturbative Hamiltonian analysis, we prove that the SO (N ) Yang-Mills (YM) theory is equivalent to the corresponding NANM, after both current conservation and the Gauss laws are imposed as initial conditions for the latter. This equivalence is independent of any gauge fixing in the YM theory. A substantial conceptual and practical improvement in the analysis arises by choosing a particular parametrization that solves the nonlinear constraint defining the NANM. This choice allows us to show that the relation between the NANM canonical variables and the corresponding ones of the YM theory, Aia and Eb j , is given by a canonical transformation. In terms of the latter variables, the NANM Hamiltonian has the same form as the YM Hamiltonian, except that the Gauss laws do not arise as first-class constraints. The dynamics of the NANM further guarantees that it is sufficient to impose them only as initial conditions, in order to recover the full equivalence. It is interesting to observe that this particular parametrization exhibits the NANM as a regular theory, thus providing a substantial simplification in the calculations.
Coexisting massive and massless Dirac fermions in symmetry-broken bilayer graphene
NASA Astrophysics Data System (ADS)
Kim, Keun Su; Walter, Andrew L.; Moreschini, Luca; Seyller, Thomas; Horn, Karsten; Rotenberg, Eli; Bostwick, Aaron
2013-10-01
Charge carriers in bilayer graphene are widely believed to be massive Dirac fermions that have a bandgap tunable by a transverse electric field. However, a full transport gap, despite its importance for device applications, has not been clearly observed in gated bilayer graphene, a long-standing puzzle. Moreover, the low-energy electronic structure of bilayer graphene is widely held to be unstable towards symmetry breaking either by structural distortions, such as twist, strain, or electronic interactions that can lead to various ground states. Which effect dominates the physics at low energies is hotly debated. Here we show both by direct band-structure measurements and by calculations that a native imperfection of bilayer graphene, a distribution of twists whose size is as small as ~0.1°, is sufficient to generate a completely new electronic spectrum consisting of massive and massless Dirac fermions. The massless spectrum is robust against strong electric fields, and has a unusual topology in momentum space consisting of closed arcs having an exotic chiral pseudospin texture, which can be tuned by varying the charge density. The discovery of this unusual Dirac spectrum not only complements the framework of massive Dirac fermions, widely relevant to charge transport in bilayer graphene, but also supports the possibility of valley Hall transport.
Relaxing the electroweak scale: the role of broken dS symmetry
NASA Astrophysics Data System (ADS)
Patil, Subodh P.; Schwaller, Pedro
2016-02-01
Recently, a novel mechanism to address the hierarchy problem has been proposed [1], where the hierarchy between weak scale physics and any putative `cutoff' M is translated into a parametrically large field excursion for the so-called relaxion field, driving the Higgs mass to values much less than M through cosmological dynamics. In its simplest incarnation, the relaxion mechanism requires nothing beyond the standard model other than an axion (the relaxion field) and an inflaton. In this note, we critically re-examine the requirements for successfully realizing the relaxion mechanism and point out that parametrically larger field excursions can be obtained for a given number of e-folds by simply requiring that the background break exact de Sitter invariance. We discuss several corollaries of this observation, including the interplay between the upper bound on the scale M and the order parameter ɛ associated with the breaking of dS symmetry, and entertain the possibility that the relaxion could play the role of a curvaton. We find that a successful realization of the mechanism is possible with as few as O(1{0}^3) e-foldings, albeit with a reduced cutoff M ˜ 106 GeV for a dark QCD axion and outline a minimal scenario that can be made consistent with CMB observations.
Universal horizons and black holes in gravitational theories with broken Lorentz symmetry
NASA Astrophysics Data System (ADS)
Lin, Kai; Abdalla, Elcio; Cai, Rong-Gen; Wang, Anzhong
2014-10-01
In this paper, we first show that the definition of the universal horizons studied recently in the khronometric theory of gravity can be straightforwardly generalized to other theories that violate the Lorentz symmetry, by simply considering the khronon as a probe field and playing the same role as a Killing vector field. As an application, we study static charged (D + 1)-dimensional spacetimes in the framework of the healthy (nonprojectable) Horava-Lifshitz (HL) gravity in the infrared (IR) limit, and find various solutions. Some of them represent Lifshitz spacetimes with hyperscaling violations, and some have black hole structures. In the latter, universal horizons always exist inside the Killing horizons. The surface gravity on them can be either larger or smaller than the surface gravity on the Killing horizons, depending on the spacetimes considered. Although such black holes are found only in the IR, we argue that black holes with universal horizons also exist in the full theory of the HL gravity. A simple example is the Schwarzschild solution written in the Painleve-Gullstrand coordinates, which is also a solution of the full theory of the HL gravity and has a universal horizon located inside the Schwarzschild Killing horizon.
Charmless decays B{yields}{pi}{pi},{pi}K and KK in broken SU(3) symmetry
Wu Yueliang; Zhou Yufeng
2005-08-01
Charmless B decay modes B{yields}{pi}{pi},{pi}K and KK are systematically investigated with and without flavor SU(3) symmetry. Independent analyses on {pi}{pi} and {pi}K modes both favor a large ratio between color-suppressed tree (C) and tree (T) diagram, which suggests that they are more likely to originate from long distance effects. The sizes of QCD penguin diagrams extracted individually from {pi}{pi}, {pi}K and KK modes are found to follow a pattern of SU(3) breaking in agreement with the naive factorization estimates. Global fits to these modes are done under various scenarios of SU(3) relations. The results show good determinations of weak phase {gamma} in consistency with the standard model (SM), but a large electroweak penguin (P{sub EW}) relative to T+C with a large relative strong phase is favored, which requires a big enhancement of color-suppressed electroweak penguin (P{sub EW}{sup C}) compatible in size but destructively interfering with P{sub EW} within the SM, or implies new physics. The possibilities of sizable contributions from nonfactorizable diagrams such as W exchange (E), annihilation (A), and penguin-annihilation diagrams (P{sub A}) are investigated. The implications to the branching ratios and CP violations in KK modes are discussed.
Gauged B-L symmetry and baryogenesis via leptogenesis at TeV scale
Sahu, Narendra; Yajnik, Urjit A.
2005-01-15
It is shown that the requirement of preservation of baryon asymmetry does not rule out a scale for leptogenesis as low as 10 TeV. The conclusions are compatible with see-saw mechanism if, for example, the pivot mass scale for neutrinos is {approx_equal}10{sup -2} that of the charged leptons. We explore the parameter space m-tilde{sub 1}- M{sub 1} of relevant light and heavy neutrino masses by solving Boltzmann equations. A viable scenario for obtaining baryogenesis in this way is presented in the context of gauged B-L symmetry.
Gravitational matter-antimatter asymmetry and four-dimensional Yang-Mills gauge symmetry
NASA Technical Reports Server (NTRS)
Hsu, J. P.
1981-01-01
A formulation of gravity based on the maximum four-dimensional Yang-Mills gauge symmetry is studied. The theory predicts that the gravitational force inside matter (fermions) is different from that inside antimatter. This difference could lead to the cosmic separation of matter and antimatter in the evolution of the universe. Moreover, a new gravitational long-range spin-force between two fermions is predicted, in addition to the usual Newtonian force. The geometrical foundation of such a gravitational theory is the Riemann-Cartan geometry, in which there is a torsion. The results of the theory for weak fields are consistent with previous experiments.
Confinement/deconfinement transition from symmetry breaking in gauge/gravity duality
NASA Astrophysics Data System (ADS)
Čubrović, Mihailo
2016-10-01
We study the confinement/deconfinement transition in a strongly coupled system triggered by an independent symmetry-breaking quantum phase transition in gauge/gravity duality. The gravity dual is an Einstein-scalar-dilaton system with AdS near-boundary behavior and soft wall interior at zero scalar condensate. We study the cases of neutral and charged condensate separately. In the former case the condensation breaks the discrete {Z}_2 symmetry while a charged condensate breaks the continuous U(1) symmetry. After the condensation of the order parameter, the non-zero vacuum expectation value of the scalar couples to the dilaton, changing the soft wall geometry into a non-confining and anisotropically scale-invariant infrared metric. In other words, the formation of long-range order is immediately followed by the deconfinement transition and the two critical points coincide. The confined phase has a scale — the confinement scale (energy gap) which vanishes in the deconfined case. Therefore, the breaking of the symmetry of the scalar ( {Z}_2 or U(1)) in turn restores the scaling symmetry in the system and neither phase has a higher overall symmetry than the other. When the scalar is charged the phase transition is continuous which goes against the Ginzburg-Landau theory where such transitions generically only occur discontinuously. This phenomenon has some commonalities with the scenario of deconfined criticality. The mechanism we have found has applications mainly in effective field theories such as quantum magnetic systems. We briefly discuss these applications and the relation to real-world systems.
Spin Contamination Error in Optimized Geometry of Singlet Carbene (1A1) by Broken-Symmetry Method
NASA Astrophysics Data System (ADS)
Kitagawa, Yasutaka; Saito, Toru; Nakanishi, Yasuyuki; Kataoka, Yusuke; Matsui, Toru; Kawakami, Takashi; Okumura, Mitsutaka; Yamaguchi, Kizashi
2009-10-01
Spin contamination errors of a broken-symmetry (BS) method in optimized structural parameters of the singlet methylene (1A1) molecule are quantitatively estimated for the Hartree-Fock (HF) method, post-HF methods (CID, CCD, MP2, MP3, MP4(SDQ)), and a hybrid DFT (B3LYP) method. For the purpose, the optimized geometry by the BS method is compared with that of an approximate spin projection (AP) method. The difference between the BS and the AP methods is about 10-20° in the HCH angle. In order to examine the basis set dependency of the spin contamination error, calculated results by STO-3G, 6-31G*, and 6-311++G** are compared. The error depends on the basis sets, but the tendencies of each method are classified into two types. Calculated energy splitting values between the triplet and the singlet states (ST gap) indicate that the contamination of the stable triplet state makes the BS singlet solution stable and the ST gap becomes small. The energy order of the spin contamination error in the ST gap is estimated to be 10-1 eV.
Bigelow, Nicholas W; Vaschillo, Alex; Camden, Jon P; Masiello, David J
2013-05-28
Through numerical simulation, we predict the existence of the Fano interference effect in the electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) of symmetry-broken nanorod dimers that are heterogeneous in material composition and asymmetric in length. The differing selection rules of the electron probe in comparison to the photon of a plane wave allow for the simultaneous excitation of both optically bright and dark plasmons of each monomer unit, suggesting that Fano resonances will not arise in EELS and CL. Yet, interferences are manifested in the dimer's scattered near- and far-fields and are evident in EELS and CL due to the rapid π-phase offset in the polarizations between super-radiant and subradiant hybridized plasmon modes of the dimer as a function of the energy loss suffered by the impinging electron. Depending upon the location of the electron beam, we demonstrate the conditions under which Fano interferences will be present in both optical and electron spectroscopies (EELS and CL) as well as a new class of Fano interferences that are uniquely electron-driven and are absent in the optical response. Among other things, the knowledge gained from this work bears impact upon the design of some of the world's most sensitive sensors, which are currently based upon Fano resonances.
Quantum oscillations in a bilayer with broken mirror symmetry: a minimal model for YBa2Cu3O6+δ
NASA Astrophysics Data System (ADS)
Maharaj, Akash; Zhang, Yi; Ramshaw, Brad; Kivelson, Steven
Using an exact numerical solution and semiclassical analysis, we investigate quantum oscillations (QOs) in a model of a bilayer system with an anisotropic (elliptical) electron pocket in each plane. Key features of QO experiments in the high temperature superconducting cuprate YBCO can be reproduced by such a model, in particular the pattern of oscillation frequencies (which reflect ``magnetic breakdown'' between the two pockets) and the polar and azimuthal angular dependence of the oscillation amplitudes. However, the requisite magnetic breakdown is possible only under the assumption that the horizontal mirror plane symmetry is spontaneously broken and that the bilayer tunneling, t⊥, is substantially renormalized from its `bare' value. Under the assumption that t⊥ = Z ~t⊥(0), where Z ~ is a measure of the quasiparticle weight, this suggests that Z ~ <~ 1 / 20 . Detailed comparisons with new YBa2Cu3O6.58 QO data, taken over a very broad range of magnetic field, confirm specific predictions made by the breakdown scenario. Supported in part by the US DOE, Office of Basic Energy Sciences under Contract DE-AC02-76SF00515 (A.V.M.), the US DOE Office of Basic Energy Sciences ``Science at 100 T,'' (B.J.R.) and the National Science Foundation Grant No. DMR 1265593 (S.A.K., YZ).
Effective field theory of broken spatial diffeomorphisms
Lin, Chunshan; Labun, Lance Z.
2016-03-17
We study the low energy effective theory describing gravity with broken spatial diffeomorphism invariance. In the unitary gauge, the Goldstone bosons associated with broken diffeomorphisms are eaten and the graviton becomes a massive spin-2 particle with 5 well-behaved degrees of freedom. In this gauge, the most general theory is built with the lowest dimension operators invariant under only temporal diffeomorphisms. Imposing the additional shift and SO(3) internal symmetries, we analyze the perturbations on a FRW background. At linear perturbation level, the observables of this theory are characterized by five parameters, including the usual cosmological parameters and one additional coupling constantmore » for the symmetry-breaking scalars. In the de Sitter and Minkowski limit, the three Goldstone bosons are supermassive and can be integrated out, leaving two massive tensor modes as the only propagating degrees of freedom. In conclusion, we discuss several examples relevant to theories of massive gravity.« less
Effective field theory of broken spatial diffeomorphisms
Lin, Chunshan; Labun, Lance Z.
2016-03-17
We study the low energy effective theory describing gravity with broken spatial diffeomorphism invariance. In the unitary gauge, the Goldstone bosons associated with broken diffeomorphisms are eaten and the graviton becomes a massive spin-2 particle with 5 well-behaved degrees of freedom. In this gauge, the most general theory is built with the lowest dimension operators invariant under only temporal diffeomorphisms. Imposing the additional shift and SO(3) internal symmetries, we analyze the perturbations on a FRW background. At linear perturbation level, the observables of this theory are characterized by five parameters, including the usual cosmological parameters and one additional coupling constant for the symmetry-breaking scalars. In the de Sitter and Minkowski limit, the three Goldstone bosons are supermassive and can be integrated out, leaving two massive tensor modes as the only propagating degrees of freedom. In conclusion, we discuss several examples relevant to theories of massive gravity.
Gauged R-symmetry and its anomalies in 4D N=1 supergravity and phenomenological implications
NASA Astrophysics Data System (ADS)
Antoniadis, I.; Ghilencea, D. M.; Knoops, R.
2015-02-01
We consider a class of models with gauged U(1) R symmetry in 4D N=1 super-gravity that have, at the classical level, a metastable ground state, an infinitesimally small (tunable) positive cosmological constant and a TeV gravitino mass. We analyse if these properties are maintained under the addition of visible sector (MSSM-like) and hidden sector state(s), where the latter may be needed for quantum consistency. We then discuss the anomaly cancellation conditions in supergravity as derived by Freedman, Elvang and Körs and apply their results to the special case of a U(1) R symmetry, in the presence of the Fayet-Iliopoulos term ( ξ) and Green-Schwarz mechanism(s). We investigate the relation of these anomaly cancellation conditions to the "naive" field theory approach in global SUSY, in which case U(1) R cannot even be gauged. We show the two approaches give similar conditions. Their induced constraints at the phenomenological level, on the above models, remain strong even if one lifted the GUT-like conditions for the MSSM gauge couplings. In an anomaly-free model, a tunable, TeV-scale gravitino mass may remain possible provided that the U(1) R charges of additional hidden sector fermions (constrained by the cubic anomaly alone) do not conflict with the related values of U(1) R charges of their scalar superpartners, constrained by existence of a stable ground state. This issue may be bypassed by tuning instead the coefficients of the Kahler connection anomalies ( b K , b CK ).
Some comments on unitarity gauge
NASA Astrophysics Data System (ADS)
Lopez-Osorio, M. A.; Martinez-Pascual, E.; Toscano, J. J.
2004-04-01
A pedagogical discussion on the unitarity gauge within the context of Hamiltonian path integral formalism is presented. A model based on the group O(N), spontaneously broken down to the subgroup O(N - 1), is used to illustrate the main aspects of this gauge-fixing procedure. Among the issues, discussed with some extent, are: (1) the structure of model's constraints following the Dirac's method, (2) the gauge-fixing procedure, using the unitarity gauge for the massive gauge fields and the Coulomb one for the massless gauge fields, (3) the absence of BRST symmetry in this gauge-fixing procedure and its implications on the renormalizability of the theory, and (4) the static role of the ghost and anti-ghost fields associated with the massive gauge fields and how their contributions can be eliminated by using the dimensional regularization scheme.
Dark matter, {mu} problem, and neutrino mass with gauged R symmetry
Choi, Ki-Young; Chun, Eung Jin; Lee, Hyun Min
2010-11-15
We show that the {mu} problem and the strong CP problem can be resolved in the context of the gauged U(1){sub R} symmetry, realizing an automatic Peccei-Quinn symmetry. In this scheme, right-handed neutrinos can be introduced to explain small Majorana or Dirac neutrino mass. The U(1){sub R} D-term mediated supersymmetry (SUSY) breaking, called the U(1){sub R} mediation, gives rise to a specific form of the flavor-conserving superpartner masses. For the given solution to the {mu} problem, electroweak symmetry breaking condition requires the superpartners of the standard model at low energy to be much heavier than the gravitino. Thus, the dark matter candidate can be either gravitino or right-handed sneutrino. In the Majorana neutrino case, only gravitino is a natural dark matter candidate. On the other hand, in the Dirac neutrino case, the right-handed sneutrino can be also a dark matter candidate as it gets mass only from SUSY breaking. We discuss the non-thermal production of our dark matter candidates from the late decay of stau and find that the constraints from the big bang nucleosynthesis can be evaded for a TeV-scale stau mass.
Muresan, Nicoleta; Lu, Connie C; Ghosh, Meenakshi; Peters, Jonas C; Abe, Megumi; Henling, Lawrence M; Weyhermöller, Thomas; Bill, Eckhard; Wieghardt, Karl
2008-06-02
The electronic structure of a family comprising tetrahedral (alpha-diimine)iron dichloride, and tetrahedral bis(alpha-diimine)iron compounds has been investigated by Mossbauer spectroscopy, magnetic susceptibility measurements, and X-ray crystallography. In addition, broken-symmetry density functional theoretical (B3LYP) calculations have been performed. A detailed understanding of the electronic structure of these complexes has been obtained. A paramagnetic (St=2), tetrahedral complex [FeII(4L)2], where (4L)1- represents the diamagnetic monoanion N-tert-butylquinolinylamide, has been synthesized and characterized to serve as a benchmark for a Werner-type complex containing a tetrahedral FeIIN4 geometry and a single high-spin ferrous ion. In contrast to the most commonly used description of the electronic structure of bis(alpha-diimine)iron(0) complexes as low-valent iron(0) species with two neutral alpha-diimine ligands, it is established here that they are, in fact, complexes containing two (alpha-diiminato)1-* pi radical monoanions and a high-spin ferrous ion (in tetrahedral N4 geometry) (SFe=2). Intramolecular antiferromagnetic coupling between the pi radical ligands (Srad=1/2) and the ferrous ion (SFe=2) yields the observed St=1 ground state. The study confirms that alpha-diimines are redox noninnocent ligands with an energetically low-lying antibonding pi* lowest unoccupied molecular orbital which can accept one or two electrons from a transition metal ion. The (alpha-diimine)FeCl2 complexes (St=2) are shown to contain a neutral alpha-diimine ligand, a high spin ferrous ion, and two chloride ligands.
Einstein-vector gravity, emerging gauge symmetry, and de Sitter bounce
NASA Astrophysics Data System (ADS)
Geng, Wei-Jian; Lü, H.
2016-02-01
We construct a class of Einstein-vector theories where the vector field couples bilinearly to the curvature polynomials of arbitrary order in such a way that only the Riemann tensor rather than its derivative enters the equations of motion. The theories can thus be ghost free. The U (1 ) gauge symmetry may emerge in the vacuum and also in some weak-field limit. We focus on the two-derivative theory and study a variety of applications. We find that in this theory, the energy-momentum tensor of dark matter provides a position-dependent gauge-violating term to the Maxwell field. We also use the vector as an inflaton and construct cosmological solutions. We find that the expansion can accelerate without a bare cosmological constant, indicating a new candidate for dark energy. Furthermore, we obtain exact solutions of de Sitter bounce, generated by the vector which behaves like a Maxwell field at later times. We also obtain a few new exact black holes that are asymptotic to flat and Lifshitz spacetimes. In addition, we construct exact wormholes and Randall-Sundrum II domain walls.
Boundaries, mirror symmetry, and symplectic duality in 3d N=4 gauge theory
NASA Astrophysics Data System (ADS)
Bullimore, Mathew; Dimofte, Tudor; Gaiotto, Davide; Hilburn, Justin
2016-10-01
We introduce several families of N=(2, 2) UV boundary conditions in 3d N=4 gaugetheoriesandstudytheirIRimagesinsigma-modelstotheHiggsandCoulomb branches. In the presence of Omega deformations, a UV boundary condition defines a pair of modules for quantized algebras of chiral Higgs- and Coulomb-branch operators, respec-tively, whose structure we derive. In the case of abelian theories, we use the formalism of hyperplane arrangements to make our constructions very explicit, and construct a half-BPS interface that implements the action of 3d mirror symmetry on gauge theories and boundary conditions. Finally, by studying two-dimensional compactifications of 3d N=4 gauge theories and their boundary conditions, we propose a physical origin for symplectic duality — an equivalence of categories of modules associated to families of Higgs and Coulomb branches that has recently appeared in the mathematics literature, and generalizes classic results on Koszul duality in geometric representation theory. We make several predictions about the structure of symplectic duality, and identify Koszul duality as a special case of wall crossing.
NASA Astrophysics Data System (ADS)
Wang, Juven; Gu, Zheng-Cheng; Wen, Xiao-Gang
The challenge of identifying symmetry-protected topological states (SPTs) is due to their lack of symmetry-breaking order parameters and intrinsic topological orders. For this reason, it is impossible to formulate SPTs under Ginzburg-Landau theory or probe SPTs via fractionalized bulk excitations and topology-dependent ground state degeneracy. However, the partition functions from path integrals with various symmetry twists are universal SPT invariants, fully characterizing SPTs. In this work, we use gauge fields to represent those symmetry twists in closed spacetimes of any dimensionality and arbitrary topology. This allows us to express the SPT invariants in terms of continuum field theory. We show that SPT invariants of pure gauge actions describe the SPTs predicted by group cohomology, while the mixed gauge-gravity actions describe the beyond-group-cohomology SPTs, recently observed by Kapustin. We find new examples of mixed gauge-gravity actions for U(1) SPTs in 3+1D and 4+1D via the Stiefel-Whitney class and the gravitational Chern-Simons term. [Work based on Phys. Rev. Lett. 114, 031601 (2015) arXiv:1405.7689
Mouesca, Jean-Marie
2014-01-01
The goal of this "how to" chapter is to present in a way as simple and practical as possible some of the concepts, key issues, and practices behind the so-called broken symmetry (BS) state which is widely used within the density functional theory (DFT) (for a very nice but thoughtful introduction to DFT (without equations!), read Perdew et al. (J Chem Theory Comput 5:902-908, 2009)) community to compute energetic as well as spectroscopic properties pertaining to (poly-)radicals, bioinorganic clusters (especially those containing transition metal ions), etc. Such properties encompass exchange coupling constants J (molecular magnetism) but also (among other things) g-tensors and hyperfine coupling tensors A (from electron paramagnetic resonance), isomer shifts δ and quadrupolar tensors ΔE Q (from Mössbauer), etc.Hopefully, this chapter will appeal to those DFT practitioners who would like to understand the basics behind the BS state and help them "demystify" some of the issues involved with them. More technical issues will only be alluded to, and appropriate references will be given for those interested to go beyond this mere introduction. This chapter is however not a review of the field. Consequently, it will be primarily based on my own experience. The goal here (in the spirit of a "how to" chapter) is to accompany the readers' thoughts in a progressive way along increasingly complex issues rather than encumbering the same thoughts with too complicate mathematical details (the few derivations which are given will therefore be explicit). Moreover, I will emphasize in this chapter the interplay between the computation of BS states on the one hand, and the derivation of phenomenological models on the other hand, whose parameters can be supplied from appropriate BS states. Finally, this chapter is dedicated to Louis Noodleman (Scripps Research Institute, CA, USA), pioneer (Noodleman, J Chem Phys 74:5737-5743, 1981; Noodleman, Chem Phys 109:131-143, 1986) and
NASA Astrophysics Data System (ADS)
He, Huan; Zheng, Yunqin; von Keyserlingk, Curt
2017-01-01
Dijkgraaf-Witten (DW) theories are of recent interest to the condensed matter community, in part because they represent topological phases of matter, but also because they characterize the response theory of certain symmetry protected topological (SPT) phases. However, as yet there has not been a comprehensive treatment of the spectra of these models in the field theoretic setting even for Abelian gauge groups, the goal of this work is to fill the gap in the literature, especially for a selection of DW models with Abelian gauge groups but non-Abelian topological order. Particularly, we focus on the appearance of non-Abelian statistics in type-III twisted DW theories with Abelian gauge groups Z2⊗3. There are only 22 distinguishable line operators, and their fusion rules and correlation functions are calculated. The flux insertion operators have quantum dimension 2, which clearly demonstrates the non-Abelian topological order of type-III twisted DW theories.
Kasamatsu, Kenichi; Ichinose, Ikuo; Matsui, Tetsuo
2013-09-13
Recently, the possibility of quantum simulation of dynamical gauge fields was pointed out by using a system of cold atoms trapped on each link in an optical lattice. However, to implement exact local gauge invariance, fine-tuning the interaction parameters among atoms is necessary. In the present Letter, we study the effect of violation of the U(1) local gauge invariance by relaxing the fine-tuning of the parameters and showing that a wide variety of cold atoms is still a faithful quantum simulator for a U(1) gauge-Higgs model containing a Higgs field sitting on sites. The clarification of the dynamics of this gauge-Higgs model sheds some light upon various unsolved problems, including the inflation process of the early Universe. We study the phase structure of this model by Monte Carlo simulation and also discuss the atomic characteristics of the Higgs phase in each simulator.
NASA Astrophysics Data System (ADS)
Almeida Firmo, Ines
Unconventional superconductors provide, today, some of the most fundamental challenges in condensed-matter physics, besides their unimaginable potential for applications. Here, we will discuss two of these materials. Firstly, we will focus on Sr2RuO4, one of the most promising candidates to exhibit chiral p-wave superconductivity, analogously to a two-dimensional (2D) film of 3He-A. Some of the outstanding challenges regarding this multi-band superconductor remain, including the knowledge of which band(s) are primarily responsible for the appearance of superconductivity. Solving this issue will help us understand the symmetry of the pairing and, eventually, the pairing mechanism. We report scanning tunneling microscopy (STM) studies confirming a nodal superconducting gap structure and indicating that the quasi-one-dimensional (1D) bands are most important for superconductivity in Sr2RuO4. We suggest an experimental avenue to confirm this observation and determine the pairing symmetry beyond doubt. We then turn to a discussion of the hole-doped cuprate high-temperature superconductors, with a focus on their mysterious pseudogap regime and its Q = 0 and Q ≠ 0 electronic broken symmetries. Development of novel spectroscopic imaging STM (SI-STM) techniques allowed the quantitative measurement of such broken symmetries (also seen by other probes) and their inter-relations. We report on these novel techniques in detail, in particular Fourier phase determination of STM data, and study extensively the hole doping, p, dependence of the broken symmetries as well as the Fermi surface topology for Bi2Sr 2CaCu2O8+delta samples spanning the phase diagram between 0.06 ≤ p ≤ 0.23. We show that the electronic symmetry breaking tendencies weaken with increasing p and disappear close to pc = 0.19. Concomitantly, the coherent k-space topology undergoes an abrupt transition, from arcs to closed contours, at the same pc. These data reveal that the k-space topology transformation
NASA Technical Reports Server (NTRS)
Lee, Kimyeong; Stein-Schabes, Jaime A.; Watkins, Richard; Widrow, Lawrence M.
1988-01-01
Classical non-topological soliton configurations are considered within the theory of a complex scalar field with a gauged U symmetry. Their existence and stability against dispersion are demonstrated and some of their properties are investigated analytically and numerically. The soliton configuration is such that inside the soliton the local U symmetry is broken, the gauge field becomes massive and for a range of values of the coupling constants the soliton becomes a superconductor pushing the charge to the surface. Furthermore, because of the repulsive Coulomb force, there is a maximum size for these objects, making impossible the existence of Q-matter in bulk form. Also briefly discussed are solitons with fermions in a U gauge theory.
Supersymmetry breaking from superstrings and the gauge hierarchy
Gaillard, M.K. California Univ., Berkeley, CA . Dept. of Physics)
1990-07-11
The gauge hierarchy problem is reviewed and a class of effective field theories obtained from superstrings is described. These are characterized by a classical symmetry, related to the space-time duality of string theory, that is responsible for the suppression of observable supersymmetry breaking effects. At the quantum level, the symmetry is broken by anomalies that provide the seed of observable supersymmetry breaking, and an acceptably large gauge hierarchy may be generated. 39 refs.
de la Lande, A.; Maddaluno, J.; Parisel, O.; Darden, T. A.; Piquemal, J-P
2010-01-01
Following our previous study (Piquemal et al., New J. Chem., 2003, 27, 909), we present here a DFT study of the inhibition of the Tyrosinase enzyme. Broken-symmetry DFT computations are supplemented with Spin-Flip TD-DFT calculations, which, for the first time, are applied to such a dicopper enzyme. The chosen biomimetic model encompasses a dioxygen molecule, two Cu(II) cations, and six imidazole rings. The docking energy of a natural substrate, namely phenolate, together with those of several inhibitor and non-inhibitor compounds, are reported and show the ability of the model to rank the most potent inhibitors in agreement with experimental data. With respect to broken-symmetry calculations, the Spin-Flip TD-DFT approach reinforces the possibility for theory to point out potent inhibitors: the need for the deprotonation of the substrates, natural or inhibitors, is now clearly established. Moreover, Electron Localization Function (ELF) topological analysis computations are used to deeply track the particular electronic distribution of the Cu-O-Cu three-center bonds involved in the enzymatic Cu2O2 metallic core (Piquemal and Pilmé, J. Mol. Struct.: Theochem, 2006, 77, 764). It is shown that such bonds exhibit very resilient out-of-plane density expansions that play a key role in docking interactions: their 3D-orientation could be the topological electronic signature of oxygen activation within such systems. PMID:20396590
de la Lande, A; Maddaluno, J; Parisel, O; Darden, T A; Piquemal, J-P
2010-03-01
Following our previous study (Piquemal et al., New J. Chem., 2003, 27, 909), we present here a DFT study of the inhibition of the Tyrosinase enzyme. Broken-symmetry DFT computations are supplemented with Spin-Flip TD-DFT calculations, which, for the first time, are applied to such a dicopper enzyme. The chosen biomimetic model encompasses a dioxygen molecule, two Cu(II) cations, and six imidazole rings. The docking energy of a natural substrate, namely phenolate, together with those of several inhibitor and non-inhibitor compounds, are reported and show the ability of the model to rank the most potent inhibitors in agreement with experimental data. With respect to broken-symmetry calculations, the Spin-Flip TD-DFT approach reinforces the possibility for theory to point out potent inhibitors: the need for the deprotonation of the substrates, natural or inhibitors, is now clearly established. Moreover, Electron Localization Function (ELF) topological analysis computations are used to deeply track the particular electronic distribution of the Cu-O-Cu three-center bonds involved in the enzymatic Cu(2)O(2) metallic core (Piquemal and Pilmé, J. Mol. Struct.: Theochem, 2006, 77, 764). It is shown that such bonds exhibit very resilient out-of-plane density expansions that play a key role in docking interactions: their 3D-orientation could be the topological electronic signature of oxygen activation within such systems.
Origin of Abelian gauge symmetries in heterotic/F-theory duality
Cvetič, Mirjam; Grassi, Antonella; Klevers, Denis; Poretschkin, Maximilian; Song, Peng
2016-04-07
Here, we study aspects of heterotic/F-theory duality for compactifications with Abelian gauge symmetries. We consider F-theory on general Calabi-Yau manifolds with a rank one Mordell-Weil group of rational sections. By rigorously performing the stable degeneration limit in a class of toric models, and also derive both the Calabi-Yau geometry and the spectral cover describing the vector bundle in the heterotic dual theory. We carefully investigate the spectral cover employing the group law on the elliptic curve in the heterotic theory. We find in explicit examples that there are three different classes of heterotic duals that have U(1) factors in their low energy effective theories: split spectral covers describing bundles with S(U(m) x U(1)) structure group, spectral covers containing torsional sections that seem to give rise to bundles with SU(m) x Z_k structure group and bundles with purely non-Abelian structure groups having a centralizer in E_8 containing a U(1) factor. In the former two cases, it is required that the elliptic fibration on the heterotic side has a non-trivial Mordell-Weil group. And while the number of geometrically massless U(1)'s is determined entirely by geometry on the F-theory side, on the heterotic side the correct number of U(1)'s is found by taking into account a Stuckelberg mechanism in the lower-dimensional effective theory. Finally, in geometry, this corresponds to the condition that sections in the two half K3 surfaces that arise in the stable degeneration limit of F-theory can be glued together globally.
Origin of Abelian gauge symmetries in heterotic/F-theory duality
Cvetič, Mirjam; Grassi, Antonella; Klevers, Denis; ...
2016-04-07
Here, we study aspects of heterotic/F-theory duality for compactifications with Abelian gauge symmetries. We consider F-theory on general Calabi-Yau manifolds with a rank one Mordell-Weil group of rational sections. By rigorously performing the stable degeneration limit in a class of toric models, and also derive both the Calabi-Yau geometry and the spectral cover describing the vector bundle in the heterotic dual theory. We carefully investigate the spectral cover employing the group law on the elliptic curve in the heterotic theory. We find in explicit examples that there are three different classes of heterotic duals that have U(1) factors in theirmore » low energy effective theories: split spectral covers describing bundles with S(U(m) x U(1)) structure group, spectral covers containing torsional sections that seem to give rise to bundles with SU(m) x Z_k structure group and bundles with purely non-Abelian structure groups having a centralizer in E_8 containing a U(1) factor. In the former two cases, it is required that the elliptic fibration on the heterotic side has a non-trivial Mordell-Weil group. And while the number of geometrically massless U(1)'s is determined entirely by geometry on the F-theory side, on the heterotic side the correct number of U(1)'s is found by taking into account a Stuckelberg mechanism in the lower-dimensional effective theory. Finally, in geometry, this corresponds to the condition that sections in the two half K3 surfaces that arise in the stable degeneration limit of F-theory can be glued together globally.« less
NASA Astrophysics Data System (ADS)
Ščepka, T.; Polakovič, T.; Šoltýs, J.; Tóbik, J.; Kulich, M.; Kúdela, R.; Dérer, J.; Cambel, V.
2015-11-01
We studied vortex nucleation/annihilation process and its temperature dependence in micromagnetic objects with lowered symmetry using micro-Hall magnetometry. Magnetization reversal curves were obtained for the Pacman-like nanodots placed directly on Hall probes. Lowered symmetry of the object leads to good control of its chirality. Vortex nucleation and annihilation fields strongly depend on the angle of the external in-plane magnetic field with respect on the nanodot symmetry. The micromagnetic simulations support the experimental results - the vortex nucleation fields are controlled by local magnetization configurations present in the object (C-, S-, and double S-states) for field just above vortex nucleation field. The experiments also confirm that the vortex nucleation proceeds via thermal activation over an energy barrier.
Okada, Yoshinori; Dhital, Chetan; Zhou, Wenwen; Huemiller, Erik D; Lin, Hsin; Basak, S; Bansil, A; Huang, Y-B; Ding, H; Wang, Z; Wilson, Stephen D; Madhavan, V
2011-05-20
We study interference patterns of a magnetically doped topological insulator Bi(2-x)Fe(x)Te(3+d) by using Fourier transform scanning tunneling spectroscopy and observe several new scattering channels. A comparison with angle-resolved photoemission spectroscopy allows us to unambiguously ascertain the momentum-space origin of distinct dispersing channels along high-symmetry directions and identify those originating from time-reversal symmetry breaking. Our analysis also reveals that the surface state survives far above the energy where angle-resolved photoemission spectroscopy finds the onset of continuum bulk bands.
Gauge and global symmetries of the candidate partially massless bimetric gravity
NASA Astrophysics Data System (ADS)
Apolo, Luis; Hassan, S. F.; Lundkvist, Anders
2016-12-01
In this paper we investigate a particular ghost-free bimetric theory that exhibits the partially massless (PM) symmetry at quadratic order. At this order the global S O (1 ,4 ) symmetry of the theory is enhanced to S O (1 ,5 ). We show that this global symmetry becomes inconsistent at cubic order, in agreement with a previous calculation. Furthermore, we find that the PM symmetry of this theory cannot be extended beyond cubic order in the PM field. More importantly, it is shown that the PM symmetry cannot be extended to quartic order in any theory with one massless and one massive spin-2 fields.
Aspelmeier, T; Wang, Wenlong; Moore, M A; Katzgraber, Helmut G
2016-08-01
The one-dimensional Ising spin-glass model with power-law long-range interactions is a useful proxy model for studying spin glasses in higher space dimensions and for finding the dimension at which the spin-glass state changes from having broken replica symmetry to that of droplet behavior. To this end we have calculated the exponent that describes the difference in free energy between periodic and antiperiodic boundary conditions. Numerical work is done to support some of the assumptions made in the calculations and to determine the behavior of the interface free-energy exponent of the power law of the interactions. Our numerical results for the interface free-energy exponent are badly affected by finite-size problems.
NASA Astrophysics Data System (ADS)
Aspelmeier, T.; Wang, Wenlong; Moore, M. A.; Katzgraber, Helmut G.
2016-08-01
The one-dimensional Ising spin-glass model with power-law long-range interactions is a useful proxy model for studying spin glasses in higher space dimensions and for finding the dimension at which the spin-glass state changes from having broken replica symmetry to that of droplet behavior. To this end we have calculated the exponent that describes the difference in free energy between periodic and antiperiodic boundary conditions. Numerical work is done to support some of the assumptions made in the calculations and to determine the behavior of the interface free-energy exponent of the power law of the interactions. Our numerical results for the interface free-energy exponent are badly affected by finite-size problems.
NASA Astrophysics Data System (ADS)
Zhang, Lei; Chen, Zhida
2001-09-01
Magnetic exchange interaction for the μ-hydroxo bridged vanadium(IV) dimers is investigated based on calculations of density functional theory combined with the broken-symmetry approach. It is found that there is an exponential correlation between the V-O(hydroxo)-V angle, the V-O(hydroxo) distance and the exchange coupling constants J. Meanwhile, the calculated results reveal that the deprotonation of the bridging hydroxo ligand causes a sharp increase of the exchange coupling interaction, but the magnetic coupling constant J is insensitive to the deprotonation of the bridging aquo ligand. Moreover, simplifying each 1,2-bridging squarate ligand with two -OCH 2 groups almost does not influence magnetic exchange behavior between the two vanadium(IV) ions, and the principle of the shortest superexchange pathway is available for the multiplicity of the bridging ligand in the μ-hydroxo bridged vanadium(IV) dimers.
NASA Astrophysics Data System (ADS)
Miyakawa, Takahiko; Nakamura, Shin; Yabu, Hiroyuki
2017-03-01
We study the ground state of a two-component dipolar Fermi gas in a spherically symmetric harmonic trap at zero temperature. On the basis of the Thomas-Fermi-von Weizsäcker approximation, we obtain a phase diagram of the system with equal but opposite values of the magnetic moment. We find that a phase-separated state, which spontaneously breaks the spherical symmetry of the system, emerges.
Cooper, Fred; Ghoshal, Gourab; Pérez-Mercader, Juan
2013-10-01
We give a first principles derivation of the stochastic partial differential equations that describe the chemical reactions of the Gray-Scott model (GS): U+2V →[λ]3V and V → [μ]P, U → [ν]Q, with a constant feed rate for U. We find that the conservation of probability ensured by the chemical master equation leads to a modification of the usual differential equations for the GS model, which now involves two composite fields and also intrinsic noise terms. One of the composites is ψ(1) = φ(v)(2), where {φ(v)}(η) =v is the concentration of the species V and the averaging is over the internal noise η(u,v,ψ(1)). The second composite field is the product of three fields χ = λφ(u)φ(v)(2) and requires a noise source to ensure probability conservation. A third composite ψ(2) = φ(u)φ(v) can also be identified from the noise-induced reactions. The Hamiltonian that governs the time evolution of the many-body wave function, associated with the master equation, has a broken U(1) symmetry related to particle number conservation. By expanding around the (broken symmetry) zero-energy solution of the Hamiltonian (by performing a Doi shift) one obtains from our path integral formulation the usual reaction diffusion equation, at the classical level. The Langevin equations that are derived from the chemical master equation have multiplicative noise sources for the density fields φ(u), φ(v),χ that induce higher-order processes such as n → n scattering for n>3. The amplitude of the noise acting on φ(v) is itself stochastic in nature.
Becker, D. Reuter, M.
2014-11-15
The most momentous requirement a quantum theory of gravity must satisfy is Background Independence, necessitating in particular an ab initio derivation of the arena all non-gravitational physics takes place in, namely spacetime. Using the background field technique, this requirement translates into the condition of an unbroken split-symmetry connecting the (quantized) metric fluctuations to the (classical) background metric. If the regularization scheme used violates split-symmetry during the quantization process it is mandatory to restore it in the end at the level of observable physics. In this paper we present a detailed investigation of split-symmetry breaking and restoration within the Effective Average Action (EAA) approach to Quantum Einstein Gravity (QEG) with a special emphasis on the Asymptotic Safety conjecture. In particular we demonstrate for the first time in a non-trivial setting that the two key requirements of Background Independence and Asymptotic Safety can be satisfied simultaneously. Carefully disentangling fluctuation and background fields, we employ a ‘bi-metric’ ansatz for the EAA and project the flow generated by its functional renormalization group equation on a truncated theory space spanned by two separate Einstein–Hilbert actions for the dynamical and the background metric, respectively. A new powerful method is used to derive the corresponding renormalization group (RG) equations for the Newton- and cosmological constant, both in the dynamical and the background sector. We classify and analyze their solutions in detail, determine their fixed point structure, and identify an attractor mechanism which turns out instrumental in the split-symmetry restoration. We show that there exists a subset of RG trajectories which are both asymptotically safe and split-symmetry restoring: In the ultraviolet they emanate from a non-Gaussian fixed point, and in the infrared they loose all symmetry violating contributions inflicted on them by the
Stacking-dependent interlayer coupling in trilayer MoS_{2} with broken inversion symmetry
Yan, Jiaxu; Wang, Xingli; Tay, Beng Kang; Zhou, Wu; Liu, Zheng; Shen, Ze Xiang; Xia, Juan; Liu, Lei; Kuo, Jer -Lai; Chen, Shoushun
2015-11-13
The stacking configuration in few-layer two-dimensional (2D) materials results in different structural symmetries and layer-to-layer interactions, and hence it provides a very useful parameter for tuning their electronic properties. For example, ABA-stacking trilayer graphene remains semimetallic similar to that of monolayer, while ABC-stacking is predicted to be a tunable band gap semiconductor under an external electric field. Such stacking dependence resulting from many-body interactions has recently been the focus of intense research activities. Here we demonstrate that few-layer MoS_{2} samples grown by chemical vapor deposition with different stacking configurations (AA, AB for bilayer; AAB, ABB, ABA, AAA for trilayer) exhibit distinct coupling phenomena in both photoluminescence and Raman spectra. By means of ultralow-frequency (ULF) Raman spectroscopy, we demonstrate that the evolution of interlayer interaction with various stacking configurations correlates strongly with layer-breathing mode (LBM) vibrations. Our ab initio calculations reveal that the layer-dependent properties arise from both the spin–orbit coupling (SOC) and interlayer coupling in different structural symmetries. Lastly, such detailed understanding provides useful guidance for future spintronics fabrication using various stacked few-layer MoS_{2} blocks.
NASA Astrophysics Data System (ADS)
Tanuma, Y.; Tanaka, Y.; Kashiwaya, S.
2001-12-01
In order to clarify the influence of (the presence of) the broken time-reversal symmetry state (BTRSS) induced near the interface, tunneling conductance spectra in normal metal/dx2-y2-wave superconductor junctions are calculated on the basis of the quasiclassical Green's function method. The spatial dependence of the pair potential in the superconductor side is determined self-consistently. We discuss two types of the symmetry on the BTRSS: (i) dx2-y2+is-wave state and (ii) dx2-y2+idxy-wave state. It is shown that the amplitude of the subdominant component (is wave or idxy wave) is quite sensitive to the transmission coefficient of the junction. As the results, the splitting of the zero-bias conductance peak due to the BTRSS inducement is detectable only at junctions with small transmission coefficients for both cases. When the transmission coefficients are relatively large, the explicit peak splitting does not occur and the difference in the two cases appears in the height of the zero-bias peaks.
Reta, Daniel; Moreira, Ibério de P R; Illas, Francesc
2016-07-12
In the most general case of three electrons in three symmetry unrelated centers with Ŝ1 = Ŝ2 = Ŝ3 = 1/2 localized magnetic moments, the low energy spectrum consists of one quartet (Q) and two doublet (D1, D2) pure spin states. The energy splitting between these spin states can be described with the well-known Heisenberg-Dirac-Van Vleck (HDVV) model spin Hamiltonian, and their corresponding energy expressions are expressed in terms of the three different two-body magnetic coupling constants J12, J23, and J13. However, the values of all three magnetic coupling constants cannot be extracted using the calculated energy of the three spin-adapted states since only two linearly independent energy differences between pure spin states exist. This problem has been recently investigated by Reta et al. (J. Chem. Theory Comput. 2015, 11, 3650), resulting in an alternative proposal to the original Noodleman's broken symmetry mapping approach. In the present work, this proposal is validated by means of ab initio effective Hamiltonian theory, which allows a direct extraction of all three J values from the one-to-one correspondence between the matrix elements of both effective and HDVV Hamiltonian. The effective Hamiltonian matrix representation has been constructed from configuration interaction wave functions for the three spin states obtained for two model systems showing a different degree of delocalization of the unpaired electrons. These encompass a trinuclear Cu(II) complex and a π-conjugated purely organic triradical.
NASA Astrophysics Data System (ADS)
Dawber, Matthew
2013-03-01
In this talk I will present results on two superlattice systems which contain ultra fine layers of PbTiO3 and another perovskite material. In recent years, much work has been done on the PbTiO3/SrTiO3 system, with a focus on improper ferroelectricity and the arrangement of ferroelectric domains. Here, we consider two different partner materials for PbTiO3, each of which introduces markedly different behavior in the resulting superlattice. PbTiO3/SrRuO3 superlattices with ultra-thin SrRuO3 layers were studied both experimentally and using density functional theory. Due to the superlattice geometry, the samples show a large anisotropy in their electrical resistivity, which can be controlled by changing the thickness of the PbTiO3 layers. Therefore, along the ferroelectric direction, SrRuO3 layers can act as dielectric, rather than metallic, elements. We show that, by reducing the thickness of the PbTiO3 layers, an increasingly important effect of polarization asymmetry due to compositional inversion symmetry breaking occurs. The compositional inversion symmetry breaking is seen in this bi-color superlattice due to the combined variation of A and B site ions within the superlattice. We have also achieved an experimental enhancement of the piezoelectric response and dielectric tunability in artificially layered epitaxial PbTiO3/CaTiO3 superlattices through an engineered rotation of the polarization direction. As the relative layer thicknesses within the superlattice were changed from sample to sample we found evidence for polarization rotation in multiple x-ray diffraction measurements. Associated changes in functional properties were seen in electrical measurements and piezoforce microscopy. These results demonstrate a new approach to inducing polarization rotation under ambient conditions in an artificially layered thin film. Work supported by NSF DMR1055413
Simplified DM models with the full SM gauge symmetry: the case of t-channel colored scalar mediators
NASA Astrophysics Data System (ADS)
Ko, P.; Natale, Alexander; Park, Myeonghun; Yokoya, Hiroshi
2017-01-01
The general strategy for dark matter (DM) searches at colliders currently relies on simplified models. In this paper, we propose a new t-channel UV-complete simplified model that improves the existing simplified DM models in two important respects: (i) we impose the full SM gauge symmetry including the fact that the left-handed and the right-handed fermions have two independent mediators with two independent couplings, and (ii) we include the renormalization group evolution when we derive the effective Lagrangian for DM-nucleon scattering from the underlying UV complete models by integrating out the t-channel mediators. The first improvement will introduce a few more new parameters compared with the existing simplified DM models. In this study we look at the effect this broader set of free parameters has on direct detection and the mono- X + MET ( X=jet, W,Z) signatures at 13TeV LHC while maintaining gauge invariance of the simplified model under the full SM gauge group. We find that the direct detection constraints require DM masses less than 10 GeV in order to produce phenomenologically interesting collider signatures. Additionally, for a fixed mono-W cross section it is possible to see very large differences in the mono-jet cross section when the usual simplified model assumptions are loosened and isospin violation between RH and LH DM-SM quark couplings are allowed.
NASA Astrophysics Data System (ADS)
Bandos, Igor A.; Ortín, Tomás
2016-08-01
We review and investigate different aspects of scalar fields in supergravity theories both when they parametrize symmetric spaces and when they parametrize spaces of special holonomy which are not necessarily symmetric (Kähler and Quaternionic-Kähler spaces): their rôle in the definition of derivatives of the fermions covariant under the R-symmetry group and (in gauged supergravities) under some gauge group, their dualization into ( d - 2)-forms, their role in the supersymmetry transformation rules (via fermion shifts, for instance) etc. We find a general definition of momentum map that applies to any manifold admitting a Killing vector and coincides with those of the holomorphic and tri-holomorphic momentum maps in Kähler and quaternionic-Kähler spaces and with an independent definition that can be given in symmetric spaces. We show how the momen-tum map occurs ubiquitously: in gauge-covariant derivatives of fermions, in fermion shifts, in the supersymmetry transformation rules of ( d - 2)-forms etc. We also give the general structure of the Noether-Gaillard-Zumino conserved currents in theories with fields of different ranks in any dimension.
Alexandru, Andrei; Horváth, Ivan
2016-01-22
The validity of recently proposed equivalence between valence spontaneous chiral symmetry breaking (vSChSB) and chiral polarization of low energy Dirac spectrum (ChP) in SU(3) gauge theory, is examined for the case of twelve mass–degenerate fundamental quark flavors. We find that the vSChSB–ChP correspondence holds for regularized systems studied. Moreover, our results suggest that vSChSB occurs in two qualitatively different circumstances: there is a quark mass m{sub c} such that for m > m{sub c} the mode condensing Dirac spectrum exhibits standard monotonically increasing density, while for m{sub ch} < m < m{sub c} the peak around zero separates from the bulk of the spectrum, with density showing a pronounced depletion at intermediate scales. Valence chiral symmetry restoration may occur at yet smaller masses m < m{sub ch}, but this has not yet been seen by overlap valence probe, leaving the m{sub ch} = 0 possibility open. The latter option could place massless N{sub f}=12 theory outside of conformal window. Anomalous behavior of overlap Dirac spectrum for m{sub ch} < m < m{sub c} is qualitatively similar to one observed previously in zero and few–flavor theories as an effect of thermal agitation.
The role of broken symmetry in solvation of a spherical cavity in classical and quantum water models
Remsing, Richard C.; Baer, Marcel D.; Schenter, Gregory K.; Mundy, Christopher J.; Weeks, John D.
2014-08-21
Insertion of a hard sphere cavity in liquid water breaks translational symmetry and generates an electrostatic potential difference between the region near the cavity and the bulk. Here, we clarify the physical interpretation of this potential and its calculation. We also show that the electrostatic potential in the center of small, medium, and large cavities depends very sensitively on the form of the assumed molecular interactions for dfferent classical simple point-charge models and quantum mechanical DFT-based interaction potentials, as reected in their description of donor and acceptor hydrogen bonds near the cavity. These dfferences can signifcantly affect the magnitude of the scalar electrostatic potential. We argue that the result of these studies will have direct consequences toward our understanding of the thermodynamics of ion solvation through the cavity charging process. JDW and RCR are supported by the National Science Foundation (Grants CHE0848574 and CHE1300993). CJM and GKS are supported by the U.S. Department of Energy`s (DOE) Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is operated for the Department of Energy by Battelle. MDB is grateful for the support of the Linus Pauling Distinguished Postdoctoral Fellowship Program at PNNL. We acknowledge illuminating discussions and sharing of ideas and preprints with Dr. Shawn M. Kathmann and Prof. Tom Beck. The DFT simulations used resources of the National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Additional computing resources were generously allocated by PNNL's Institutional Computing program.
... through — like when you try to break a green stick of wood. Most broken bones in children ... subside before they are casted. Immobilization Restricting the movement of a broken bone in your leg is ...
... what happens when you try to break a green stick of wood. Most broken bones in children ... a general anesthetic before this procedure. Immobilization Restricting movement of a broken bone is critical to healing. ...
... include contact sports, physical fights, falls and motor vehicle accidents that result in facial trauma. A broken ... such as football or hockey Physical altercations Motor vehicle accidents Falls A broken nose can even be ...
Gauge Symmetry of the N-body Problem in the Hamilton-Jacobi Approach
2006-05-31
Mechanics. Springer- Verlag, NY. [29] Subbotin, M. F. 1958. ” Leonhard Euler and the Astronomical Problems of his Time.” In: Voprosy Istorii...space. It coincides with the regular Lagrange gauge when the perturbation is velocity-independent. 1 Euler and Lagrange 1.1 The history The planetary...exerted upon one another by Saturn and Jupiter. In the publication on the Lunar motion, dated by 1753, Euler derived the equations for the longitude of the
Single field inflation in supergravity with a U(1) gauge symmetry
Heurtier, L.; Khalil, S.; Moursy, A. E-mail: skhalil@zewailcity.edu.eg
2015-10-01
A single field inflation based on a supergravity model with a shift symmetry and U(1) extension of the MSSM is analyzed. We show that one of the real components of the two U(1) charged scalar fields plays the role of inflaton with an effective scalar potential similar to the ''new chaotic inflation'' scenario. Both non-anomalous and anomalous (with Fayet-Iliopoulos term) U(1) are studied. We show that the non-anomalous U(1) scenario is consistent with data of the cosmic microwave background and recent astrophysical measurements. A possible kinetic mixing between U(1) and U(1){sub B−L} is considered in order to allow for natural decay channels of the inflaton, leading to a reheating epoch. Upper limits on the reheating temperature thus turn out to favour an intermediate (∼ O(10{sup 13}) GeV) scale B−L symmetry breaking.
Single field inflation in supergravity with a U(1) gauge symmetry
Heurtier, L.; Khalil, S.; Moursy, A.
2015-10-19
A single field inflation based on a supergravity model with a shift symmetry and U(1) extension of the MSSM is analyzed. We show that one of the real components of the two U(1) charged scalar fields plays the role of inflaton with an effective scalar potential similar to the “new chaotic inflation” scenario. Both non-anomalous and anomalous (with Fayet-Iliopoulos term) U(1) are studied. We show that the non-anomalous U(1) scenario is consistent with data of the cosmic microwave background and recent astrophysical measurements. A possible kinetic mixing between U(1) and U(1){sub B−L} is considered in order to allow for natural decay channels of the inflaton, leading to a reheating epoch. Upper limits on the reheating temperature thus turn out to favour an intermediate (∼O(10{sup 13}) GeV) scale B−L symmetry breaking.
Natural Electroweak Breaking from a Mirror Symmetry
Chacko, Z.; Goh, Hock-Seng; Harnik, Roni
2006-06-16
We present ''twin Higgs models,'' simple realizations of the Higgs boson as a pseudo Goldstone boson that protect the weak scale from radiative corrections up to scales of order 5-10 TeV. In the ultraviolet these theories have a discrete symmetry which interchanges each standard model particle with a corresponding particle which transforms under a twin or a mirror standard model gauge group. In addition, the Higgs sector respects an approximate global symmetry. When this global symmetry is broken, the discrete symmetry tightly constrains the form of corrections to the pseudo Goldstone Higgs potential, allowing natural electroweak symmetry breaking. Precision electroweak constraints are satisfied by construction. These models demonstrate that, contrary to the conventional wisdom, stabilizing the weak scale does not require new light particles charged under the standard model gauge groups.
7D bosonic higher spin gauge theory: symmetry algebra and linearized constraints
NASA Astrophysics Data System (ADS)
Sezgin, E.; Sundell, P.
2002-07-01
We construct the minimal bosonic higher spin extension of the 7D AdS algebra SO(6,2), which we call hs(8 ∗) . The generators, which have spin s=1,3,5,… , are realized as monomials in Grassmann even spinor oscillators. Irreducibility, in the form of tracelessness, is achieved by modding out an infinite-dimensional ideal containing the traces. In this a key role is played by the tree bilinear traces which form an SU(2) K algebra. We show that gauging of hs(8 ∗) yields a spectrum of physical fields with spin s=0,2,4,… which make up a UIR of hs(8 ∗) isomorphic to the symmetric tensor product of two 6D scalar doubletons. The scalar doubleton is the unique SU(2) K invariant 6D doubleton. The spin s⩾2 sector comes from an hs(8 ∗) -valued one-form which also contains the auxiliary gauge fields required for writing the curvature constraints in covariant form. The physical spin s=0 field arises in a separate zero-form in a 'quasi-adjoint' representation of hs(8 ∗) . This zero-form also contains the spin s⩾2 Weyl tensors, i.e., the curvatures which are non-vanishing on-shell. We suggest that the hs(8 ∗) gauge theory describes the minimal bosonic, massless truncation of M-theory on AdS7× S4 in an unbroken phase where the holographic dual is given by N free (2,0) tensor multiplets for large N.
TeV-scale gauged B-L symmetry with inverse seesaw mechanism
Khalil, Shaaban
2010-10-01
We propose a modified version of the TeV-scale B-L extension of the standard model, where neutrino masses are generated through the inverse seesaw mechanism. We show that heavy neutrinos in this model can be accessible via clean signals at the LHC. The search for the extra gauge boson Z{sub B-L}{sup '} through the decay into dileptons or two dileptons plus missing energy is studied. We also show that the B-L extra Higgs boson can be directly probed at the LHC via a clean dilepton and missing energy signal.
The gauge sector of the SME with Lorentz-symmetry violation by symplectic projector method
NASA Astrophysics Data System (ADS)
Belich, H.; Santos, M. A.; Orlando, M. T. D.
2015-09-01
We propose to analyze a modified electromagnetism inspired from the gauge sector of the Standard Model extension (SME). From the point of view of a canonical formulation, we carried out the usual analysis on the constraints structure of the odd sector (Carroll-Field-Jackiw term) and a Maxwell term with an effective metric. This effective metric is obtained by a vectorial decomposition of the CPT-even term, that is absorbed in the ordinary Maxwell term. Using symplectic projector method (SPM), we obtain the dispersions relations and we have verified conditions of stability to determine the valid spectrum.
Multi-Higgs doublet models with local U(1){sub H} gauge symmetry and neutrino physics therein
Ko, P.; Yu, Chaehyun; Omura, Yuji
2014-01-01
Multi-Higgs doublet models appear in many interesting extensions of the standard model (SM). But they suffer from Higgs-mediated flavor changing neutral current (FCNC) problem which is very generic. In this talk, I describe that this problem can be resolved or mitigated if we introduce local U(1){sub H} Higgs flavor gauge symmetry. As examples, I describe chiral U(1){sub H} models where the right-handed up-type quarks also carry U(1){sub H} charges and discuss the top forward-backward asymmetry (FBA) and B → D{sup (*)}τν puzzle. Next I describe the two-Higgs doublet models where the usual Z₂ symmetry is implemented to U(1){sub H} and show how the Type-I and Type-II models are extended. One possible extension of Type-II has the same fermion contents with the leptophobic E₆Z´ model by Rosner, and I discuss the neutrino sector in this model briefly.
Gauging spacetime symmetries on the worldsheet and the geometric Langlands program — II
NASA Astrophysics Data System (ADS)
Tan, Meng-Chwan
2008-09-01
We generalise the analysis carried out in [1], and find that our previous results can be extended beyond the case of SL (N,C). In particular, we show that an equivalence — at the level of the holomorphic chiral algebra — between a bosonic string on a smooth coset manifold G/B and a B-gauged version of itself on G, will imply an isomorphism of classical Script W-algebras and a level relation which underlie a geometric Langlands correspondence for the simply-laced, complex ADE-groups. In addition, as opposed to line operators and branes of an open topological sigma-model, the Hecke operators and Hecke eigensheaves, can, instead, be physically interpreted in terms of the correlation functions of local operators in the holomorphic chiral algebra of a closed, quasi-topological sigma-model. Our present results thus serve as an alternative physical interpretation — to that of an electric-magnetic duality of four-dimensional gauge theory demonstrated earlier by Kapustin and Witten in [2]—of the geometric Langlands correspondence for complex ADE-groups. The cases with tame and mild ``ramifications'' are also discussed.
Gauging spacetime symmetries on the worldsheet and the geometric Langlands program
NASA Astrophysics Data System (ADS)
Tan, Meng-Chwan
2008-03-01
We study the two-dimensional twisted (0, 2) sigma-model on various smooth complex flag manifolds G/B, and explore its relevance to the geometric Langlands program. We find that an equivalence—at the level of the holomorphic chiral algebra—between a bosonic string on G/B and a B-gauged version of itself on G, will imply an isomorphism of classical Script W-algebras and a level relation which underlie a geometric Langlands correspondence for G = SL(N, C). This furnishes an alternative physical interpretation of the geometric Langlands correspondence for G = SL(N, C), to that demonstrated earlier by Kapustin and Witten via an electric-magnetic duality of four-dimensional gauge theory. Likewise, the Hecke operators and Hecke eigensheaves will have an alternative physical interpretation in terms of the correlation functions of local operators in the holomorphic chiral algebra of a quasi-topological sigma-model without boundaries. A forthcoming paper will investigate the interpretation of a ``quantum'' geometric Langlands correspondence for G = SL(N, C) in a similar setting, albeit with fluxes of the sigma-model moduli which induce a ``quantum'' deformation of the relevant classical algebras turned on.
Stokes' theorem, gauge symmetry and the time-dependent Aharonov-Bohm effect
Macdougall, James Singleton, Douglas
2014-04-15
Stokes' theorem is investigated in the context of the time-dependent Aharonov-Bohm effect—the two-slit quantum interference experiment with a time varying solenoid between the slits. The time varying solenoid produces an electric field which leads to an additional phase shift which is found to exactly cancel the time-dependent part of the usual magnetic Aharonov-Bohm phase shift. This electric field arises from a combination of a non-single valued scalar potential and/or a 3-vector potential. The gauge transformation which leads to the scalar and 3-vector potentials for the electric field is non-single valued. This feature is connected with the non-simply connected topology of the Aharonov-Bohm set-up. The non-single valued nature of the gauge transformation function has interesting consequences for the 4-dimensional Stokes' theorem for the time-dependent Aharonov-Bohm effect. An experimental test of these conclusions is proposed.
Generalizing twisted gauge invariance
Duenas-Vidal, Alvaro; Vazquez-Mozo, Miguel A.
2009-05-01
We discuss the twisting of gauge symmetry in noncommutative gauge theories and show how this can be generalized to a whole continuous family of twisted gauge invariances. The physical relevance of these twisted invariances is discussed.
Destri, C.; Vega, H. J. de; Sanchez, N. G.
2008-02-15
We perform a Monte Carlo Markov chains (MCMC) analysis of the available cosmic microwave background (CMB) and large scale structure (LSS) data (including the three years WMAP data) with single field slow-roll new inflation and chaotic inflation models. We do this within our approach to inflation as an effective field theory in the Ginsburg-Landau spirit with fourth degree trinomial potentials in the inflaton field {phi}. We derive explicit formulae and study in detail the spectral index n{sub s} of the adiabatic fluctuations, the ratio r of tensor to scalar fluctuations, and the running index dn{sub s}/dlnk. We use these analytic formulas as hard constraints on n{sub s} and r in the MCMC analysis. Our analysis differs in this crucial aspect from previous MCMC studies in the literature involving the WMAP3 data. Our results are as follows: (i) The data strongly indicate the breaking (whether spontaneous or explicit) of the {phi}{yields}-{phi} symmetry of the inflaton potentials both for new and for chaotic inflation. (ii) Trinomial new inflation naturally satisfies this requirement and provides an excellent fit to the data. (iii) Trinomial chaotic inflation produces the best fit in a very narrow corner of the parameter space. (iv) The chaotic symmetric trinomial potential is almost certainly ruled out (at 95% C.L.). In trinomial chaotic inflation the MCMC runs go towards a potential in the boundary of the parameter space and which resembles a spontaneously symmetry broken potential of new inflation. (v) The above results and further physical analysis here lead us to conclude that new inflation gives the best description of the data. (vi) We find a lower bound for r within trinomial new inflation potentials: r>0.016(95%CL) and r>0.049(68%CL). (vii) The preferred new inflation trinomial potential is a double well, even function of the field with a moderate quartic coupling yielding as most probable values: n{sub s}{approx_equal}0.958, r{approx_equal}0.055. This value
NASA Astrophysics Data System (ADS)
Inotani, Daisuke; Hanai, Ryo; Ohashi, Yoji
2016-10-01
We extend our recent work [Y. Endo et al., Phys. Rev. A 92, 023610 (2015)], 10.1103/PhysRevA.92.023610 for a parity-mixing effect in a model of two-dimensional lattice fermions to a realistic three-dimensional ultracold Fermi gas. Including effects of broken local spatial inversion symmetry by a trap potential within the framework of the real-space Bogoliubov-de Gennes theory at T =0 , we point out that an odd-parity p -wave Cooper-pair amplitude is expected to have already been realized in previous experiments on an (even-parity) s -wave superfluid Fermi gas with spin imbalance. This indicates that when one suddenly changes the s -wave pairing interaction to an appropriate p -wave one by using a Feshbach technique in this case, a nonvanishing p -wave superfluid order parameter is immediately obtained, which is given by the product of the p -wave interaction and the p -wave pair amplitude that has already been induced in the spin-imbalanced s -wave superfluid Fermi gas. Thus, by definition, the system is in the p -wave superfluid state, at least just after this manipulation. Since the achievement of a p -wave superfluid state is one of the most exciting challenges in cold Fermi gas physics, our results may provide an alternative approach to this unconventional pairing state. In addition, since the parity-mixing effect cannot be explained as far as one deals with a trap potential in the local density approximation (LDA), it is considered as a crucial example which requires us to go beyond the LDA.
NASA Astrophysics Data System (ADS)
Konstantinou, Georgios; Moulopoulos, Konstantinos
2016-11-01
Due to the importance of gauge symmetry in all fields of physics, and motivated by an article written almost three decades ago that warns against a naive handling of gauge transformations in the Landau level problem (a quantum electron moving in a spatially uniform magnetic field), we point out a proper use of the generators of dynamical symmetries combined with gauge transformation methods to easily obtain exact analytical solutions for all Landau level-wavefunctions in arbitrary gauge. Our method is different from the old argument and provides solutions in an easier manner and in a broader set of geometries and gauges; in so doing, it eliminates the need for extra procedures (i.e. a change of basis) pointed out as a necessary step in the old literature, and gives back the standard simple result, provided that an appropriate use is made of the dynamical symmetries of the system and their generators. In this way the present work will at least be useful for university-level education, i.e. in advanced classes in quantum mechanics and condensed matter physics. In addition, it clarifies the actual role of the gauge in the Landau level problem, which often appears confusing in the usual derivations provided in textbooks. Finally, we go further by showing that a similar methodology can be made to apply to the more difficult case of a spatially non-uniform magnetic field (where closed analytical results are rare), in which case the various generators (pseudomomentum and pseudo-angular momentum) appear as line integrals of the inhomogeneous magnetic field; we give closed analytical solutions for all cases, and show how the old and rather forgotten Bawin-Burnel gauge shows up naturally as a ‘reference gauge’ in all solutions.
Gauge Theories of Vector Particles
DOE R&D Accomplishments Database
Glashow, S. L.; Gell-Mann, M.
1961-04-24
The possibility of generalizing the Yang-Mills trick is examined. Thus we seek theories of vector bosons invariant under continuous groups of coordinate-dependent linear transformations. All such theories may be expressed as superpositions of certain "simple" theories; we show that each "simple theory is associated with a simple Lie algebra. We may introduce mass terms for the vector bosons at the price of destroying the gauge-invariance for coordinate-dependent gauge functions. The theories corresponding to three particular simple Lie algebras - those which admit precisely two commuting quantum numbers - are examined in some detail as examples. One of them might play a role in the physics of the strong interactions if there is an underlying super-symmetry, transcending charge independence, that is badly broken. The intermediate vector boson theory of weak interactions is discussed also. The so-called "schizon" model cannot be made to conform to the requirements of partial gauge-invariance.
SU(3) gauge symmetry for collective rotational states in deformed nuclei
NASA Astrophysics Data System (ADS)
Rosensteel, George; Sparks, Nick
2016-09-01
How do deformed nuclei rotate? The qualitative answer is that a velocity-dependent interaction causes a strong coupling between the angular momentum and the vortex momentum (or Kelvin circulation). To achieve a quantitative explanation, we propose a significant extension of the Bohr-Mottelson legacy model in which collective wave functions are vector-valued in an irreducible representation of SU(3). This SU(3) is not the usual Elliott choice, but rather describes internal vorticity in the rotating frame. The circulation values C of an SU(3) irreducible representation, say the (8,0) for 20Ne, are C = 0, 2, 4, 6, 8, which is the same as the angular momentum spectrum in the Elliott model; the reason is a reciprocity theorem in the symplectic model. The differential geometry of Yang-Mills theory provides a natural mathematical framework to solve the angular-vortex coupling riddle. The requisite strong coupling is a ``magnetic-like'' interaction arising from the covariant derivative and the bundle connection. The model builds on prior work about the Yang-Mills SO(3) gauge group model.
Fendley, Paul; Moore, Joel E; Xu, Cenke
2007-05-01
We study a constrained statistical-mechanical model in two dimensions that has three useful descriptions. They are (i) the Ising model on the honeycomb lattice, constrained to have three up spins and three down spins on every hexagon, (ii) the three-color and fully packed loop model on the links of the honeycomb lattice, with loops around a single hexagon forbidden, and (iii) three Ising models on interleaved triangular lattices, with domain walls of the different Ising models not allowed to cross. Unlike the three-color model, the configuration space on the sphere or plane is connected under local moves. On higher-genus surfaces there are infinitely many dynamical sectors, labeled by a noncontractible set of nonintersecting loops. We demonstrate that at infinite temperature the transfer matrix admits an unusual structure related to a gauge symmetry for the same model on an anisotropic lattice. This enables us to diagonalize the original transfer matrix for up to 36 sites, finding an entropy per plaquette S/k{B} approximately 0.3661 ... centered and substantial evidence that the model is not critical. We also find the striking property that the eigenvalues of the transfer matrix on an anisotropic lattice are given in terms of Fibonacci numbers. We comment on the possibility of a topological phase, with infinite topological degeneracy, in an associated two-dimensional quantum model.
NASA Astrophysics Data System (ADS)
Dartora, C. A.; Cabrera, G. G.; Nobrega, K. Z.; Montagner, V. F.; Matielli, Marina H. K.; de Campos, Fillipi Klos Rodrigues; Filho, Horacio Tertuliano S.
2011-01-01
In the context of the paraxial regime, usually valid for optical frequencies and also in the microwave spectrum of guided waves, the propagation of electromagnetic fields can be analyzed through a paraxial wave equation, which is analogous to the nonrelativistic Schrödinger equation of quantum mechanics but replacing time t with spatial coordinate z. Considering that, here it is shown that for lossless media in optical frequencies it is possible to construct a Lagrangian operator with an one-to-one correspondence with nonrelativistic quantum mechanics, which allows someone to use the same mathematical methods and techniques for solving problems. To demonstrate that, we explore a few applications in optics with increasing levels of complexity. In the spirit of a Hamiltonian formulation, the ray-tracing trajectories of geometric optics in paraxial regime are obtained in a clear manner. Following that, the gauge symmetries of the optical-field Lagrangian density is discussed in a detailed way, leading to the general form of the interaction Hamiltonian. Through the use of perturbation theory, we discuss a classical analog for a quantum not gate, making use of mode coupling in an isotropic chiral medium. At last, we explore the optical spin Hall effect and its possible applications using an effective geometric optics equation derived from an interaction Hamiltonian for the optical fields. We also predict within the framework of paraxial optics a spin Hall effect of light induced by gravitational fields.
Dartora, C. A.; Matielli, Marina H. K.; Klos Rodrigues de Campos, Fillipi; Filho, Horacio Tertuliano S.; Cabrera, G. G.; Nobrega, K. Z.; Montagner, V. F.
2011-01-15
In the context of the paraxial regime, usually valid for optical frequencies and also in the microwave spectrum of guided waves, the propagation of electromagnetic fields can be analyzed through a paraxial wave equation, which is analogous to the nonrelativistic Schroedinger equation of quantum mechanics but replacing time t with spatial coordinate z. Considering that, here it is shown that for lossless media in optical frequencies it is possible to construct a Lagrangian operator with an one-to-one correspondence with nonrelativistic quantum mechanics, which allows someone to use the same mathematical methods and techniques for solving problems. To demonstrate that, we explore a few applications in optics with increasing levels of complexity. In the spirit of a Hamiltonian formulation, the ray-tracing trajectories of geometric optics in paraxial regime are obtained in a clear manner. Following that, the gauge symmetries of the optical-field Lagrangian density is discussed in a detailed way, leading to the general form of the interaction Hamiltonian. Through the use of perturbation theory, we discuss a classical analog for a quantum not gate, making use of mode coupling in an isotropic chiral medium. At last, we explore the optical spin Hall effect and its possible applications using an effective geometric optics equation derived from an interaction Hamiltonian for the optical fields. We also predict within the framework of paraxial optics a spin Hall effect of light induced by gravitational fields.
NASA Astrophysics Data System (ADS)
Bakke, K.; Belich, H.
2015-11-01
We discuss the appearance of geometric quantum phases for a Dirac neutral particle in the context of relativistic quantum mechanics based on possible scenarios of the Lorentz symmetry violation tensor background in the CPT-even gauge sector of Standard Model Extension. We assume that the Lorentz symmetry breaking is determined by a tensor background given by (KF)μναβ, then, relativistic analogues of the Anandan quantum phase [J. Anandan, Phys. Lett. A 138, 347 (1989)] are obtained based on the parity-even and parity-odd sectors of the tensor (KF)μναβ.
Seiberg duality versus hidden local symmetry
NASA Astrophysics Data System (ADS)
Abel, Steven; Barnard, James
2012-05-01
It is widely believed that the emergent magnetic gauge symmetry of SQCD is analogous to a hidden local symmetry (HLS). We explore this idea in detail, deriving the entire (spontaneously broken) magnetic theory by applying the HLS formalism to spontaneously broken SU( N) SQCD. We deduce the Kähler potential in the HLS description, and show that gauge and flavour symmetry are smoothly restored along certain scaling directions in moduli space. We propose that it is these symmetry restoring directions, associated with the R-symmetry of the theory, that allow full Seiberg duality. Reconsidering the origin of the magnetic gauge bosons as the ρ-mesons of the electric theory, colour-flavour locking allows a simple determination of the parameter a. Its value continuously interpolates between a = 2 on the baryonic branch of moduli space — corresponding to "vector meson dominance" — and a = 1 on the mesonic branch. Both limiting values are consistent with previous results in the literature. The HLS formalism is further applied to SO and Sp groups, where the usual Seiberg duals are recovered, as well as adjoint SQCD. Finally we discuss some possible future applications, including (naturally) the unitarisation of composite W scattering, blended Higgs/technicolour models, real world QCD and non-supersymmetric dualities.
Cao Qinghong; Khalil, Shaaban; Ma, Ernest; Okada, Hiroshi
2011-10-01
We discuss how {theta}{sub 13}{ne}0 is accommodated in a recently proposed renormalizable model of neutrino mixing using the non-Abelian discrete symmetry T{sub 7} in the context of a supersymmetric extension of the standard model with gauged U(1){sub B-L}. We predict a correlation between {theta}{sub 13} and {theta}{sub 23}, as well as the effective neutrino mass m{sub ee} in neutrinoless double beta decay.
Gauge-invariant extensions of the Proca model in a noncommutative space-time
NASA Astrophysics Data System (ADS)
Abreu, Everton M. C.; Neto, Jorge Ananias; Fernandes, Rafael L.; Mendes, Albert C. R.
2016-09-01
The gauge invariance analysis of theories described in noncommutative (NC) space-times can lead us to interesting results since noncommutativity is one of the possible paths to investigate quantum effects in classical theories such as general relativity, for example. This theoretical possibility has motivated us to analyze the gauge invariance of the NC version of the Proca model, which is a second-class system, in Dirac’s classification, since its classical formulation (commutative space-time) has its gauge invariance broken thanks to the mass term. To obtain such gauge invariant model, we have used the gauge unfixing method to construct a first-class NC version of the Proca model. We have also questioned if the gauge symmetries of NC theories are affected necessarily or not by the NC parameter. In this way, we have calculated its respective symmetries in a standard way via Poisson brackets.
Asymptotically Free Gauge Theories. I
DOE R&D Accomplishments Database
Wilczek, Frank; Gross, David J.
1973-07-01
Asymptotically free gauge theories of the strong interactions are constructed and analyzed. The reasons for doing this are recounted, including a review of renormalization group techniques and their application to scaling phenomena. The renormalization group equations are derived for Yang-Mills theories. The parameters that enter into the equations are calculated to lowest order and it is shown that these theories are asymptotically free. More specifically the effective coupling constant, which determines the ultraviolet behavior of the theory, vanishes for large space-like momenta. Fermions are incorporated and the construction of realistic models is discussed. We propose that the strong interactions be mediated by a "color" gauge group which commutes with SU(3)xSU(3). The problem of symmetry breaking is discussed. It appears likely that this would have a dynamical origin. It is suggested that the gauge symmetry might not be broken, and that the severe infrared singularities prevent the occurrence of non-color singlet physical states. The deep inelastic structure functions, as well as the electron position total annihilation cross section are analyzed. Scaling obtains up to calculable logarithmic corrections, and the naive lightcone or parton model results follow. The problems of incorporating scalar mesons and breaking the symmetry by the Higgs mechanism are explained in detail.
P T -invariant Weyl semimetals in gauge-symmetric systems
NASA Astrophysics Data System (ADS)
Lepori, L.; Fulga, I. C.; Trombettoni, A.; Burrello, M.
2016-08-01
Weyl semimetals typically appear in systems in which either time-reversal (T ) or inversion (P ) symmetry is broken. Here we show that in the presence of gauge potentials these topological states of matter can also arise in fermionic lattices preserving both T and P . We analyze in detail the case of a cubic lattice model with π fluxes, discussing the role of gauge symmetries in the formation of Weyl points and the difference between the physical and the canonical T and P symmetries. We examine the robustness of this P T -invariant Weyl semimetal phase against perturbations that remove the chiral sublattice symmetries, and we discuss further generalizations. Finally, motivated by advances in ultracold-atom experiments and by the possibility of using synthetic magnetic fields, we study the effect of random perturbations of the magnetic fluxes, which can be compared to a local disorder in realistic scenarios.
Dark matter and vectorlike leptons from gauged lepton number
NASA Astrophysics Data System (ADS)
Schwaller, Pedro; Tait, Tim M. P.; Vega-Morales, Roberto
2013-08-01
We investigate a simple model where lepton number is promoted to a local U(1)L gauge symmetry which is then spontaneously broken, leading to a viable thermal dark matter (DM) candidate and vectorlike leptons as a byproduct. The dark matter arises as part of the exotic lepton sector required by the need to satisfy anomaly cancellation and is a Dirac electroweak (mostly) singlet neutrino. It is stabilized by an accidental global symmetry of the renormalizable Lagrangian which is preserved even after the gauged lepton number is spontaneously broken and can annihilate efficiently to give the correct thermal relic abundance. We examine the ability of this model to give a viable DM candidate and discuss both direct and indirect detection implications. We also examine some of the LHC phenomenology of the associated exotic lepton sector and in particular its effects on Higgs decays.
Friedberg-Lee symmetry and tribimaximal neutrino mixing in the inverse seesaw mechanism
NASA Astrophysics Data System (ADS)
Chan, Aik Hui; Low, Hwee Boon; Xing, Zhi-Zhong
2009-10-01
The inverse seesaw mechanism with three pairs of gauge-singlet neutrinos offers a natural interpretation of the tiny masses of three active neutrinos at the TeV scale. We combine this picture with the newly proposed Friedberg-Lee (FL) symmetry in order to understand the observed pattern of neutrino mixing. We show that the FL symmetry requires only two pairs of the gauge-singlet neutrinos to be massive, implying that one active neutrino must be massless. We propose a phenomenological ansatz with broken FL symmetry and exact μ-τ symmetry in the gauge-singlet neutrino sector, and obtain the tribimaximal neutrino mixing pattern by means of the inverse seesaw relation. We demonstrate that nonunitary corrections to this result can possibly reach the percent level, and a soft breaking of μ-τ symmetry can give rise to CP violation in such a TeV-scale seesaw scenario.
Synthetic-gauge-field-induced Dirac semimetal state in an acoustic resonator system
NASA Astrophysics Data System (ADS)
Yang, Zhaoju; Gao, Fei; Shi, Xihang; Zhang, Baile
2016-12-01
Recently, a proposal of synthetic gauge field in reduced two-dimensional (2D) system from three-dimensional (3D) acoustic structure shows an analogue of the gapped Haldane model with fixed k z , and achieves the gapless Weyl semimetal phase in 3D momentum space. Here, extending this approach of synthetic gauge flux, we propose a reduced square lattice of acoustic resonators, which exhibits Dirac nodes with broken effective time-reversal symmetry. Protected by an additional hidden symmetry, these Dirac nodes with quantized values of topological charge are characterized by nonzero winding number and the finite structure exhibits flat edge modes that cannot be destroyed by perturbations.
NASA Astrophysics Data System (ADS)
Paliathanasis, A.; Krishnakumar, K.; Leach, P. G. L.
2016-04-01
We discuss the relationship between the Noether point symmetries of the geodesic Lagrangian, in a (pseudo)Riemannian manifold, with the elements of the Homothetic algebra of the space. We observe that the classification problem of the Noether symmetries for the geodesic Lagrangian is equivalent with the classification of the Homothetic algebra of the space, which in the case of a Friedmann-Lemaître-Robertson-Walker spacetime is a well-known result in the literature.
NASA Astrophysics Data System (ADS)
Shirkov, Dmitrii V.
2009-06-01
This is a retrospective historical review of the ideas that led to the concept of the spontaneous symmetry breaking (SSB), the issue that has been implemented in quantum field theory in the form of the Higgs mechanism. The key stages covered include: the Bogoliubov microscopic theory of superfluidity (1946); the Bardeen-Cooper-Schrieffer-Bogoliubov microscopic theory of superconductivity (1957); superconductivity as superfluidity of Cooper pairs (Bogoliubov, 1958); the extension of the SSB concept to simple quantum field models (early 1960s); triumph of the Higgs model in electroweak theory (early 1980s). The role and status of the Higgs mechanism in the current Standard Model are discussed.
... Feeding Your 1- to 2-Year-Old Broken Bones KidsHealth > For Parents > Broken Bones Print A A ... bone fragments in place. When Will a Broken Bone Heal? Fractures heal at different rates, depending upon ...
Global symmetries and renormalizability of Lee-Wick theories
Chivukula, R. Sekhar; Farzinnia, Arsham; Foadi, Roshan; Simmons, Elizabeth H.
2010-08-01
In this paper we discuss the global symmetries and the renormalizability of Lee-Wick (LW) scalar QED. In particular, in the ''auxiliary-field'' formalism we identify softly broken SO(1,1) global symmetries of the theory. We introduce SO(1,1) invariant gauge-fixing conditions that allow us to show in the auxiliary-field formalism directly that the number of superficially divergent amplitudes in a LW Abelian gauge theory is finite. To illustrate the renormalizability of the theory, we explicitly carry out the one-loop renormalization program in LW scalar QED and demonstrate how the counterterms required are constrained by the joint conditions of gauge and SO(1,1) invariance. We also compute the one-loop beta functions in LW scalar QED and contrast them with those of ordinary scalar QED.
NASA Astrophysics Data System (ADS)
Arakawa, Naoya
2016-11-01
I propose the emergence of the spin-orbital-coupled vector chirality in a nonfrustrated Mott insulator with the strong spin-orbit coupling due to a b -plane's inversion-symmetry (IS) breaking. I derive the superexchange interactions for a t2 g-orbital Hubbard model on a square lattice with the strong spin-orbit coupling and the IS-breaking-induced hopping integrals, and explain the microscopic origins of the Dzyaloshinsky-Moriya (DM) -type and the Kitaev-type interactions. Then, by adopting the mean-field approximation to a minimal model including only the Heisenberg-type and the DM-type nearest-neighbor interactions, I show that the IS breaking causes the spin-orbital-coupled chirality as a result of stabilizing the screw state. I also highlight the limit of the hard-pseudospin approximation in discussing the stability of the screw states in the presence of both the DM-type and the Kitaev-type interactions, and discuss its meaning. I finally discuss the effects of tetragonal crystal field and Jeff=3/2 states, and the application to the iridates near the [001 ] surface of Sr2IrO4 and the interface between Sr2IrO4 and Sr3Ir2O7 .
Toward realistic gauge-Higgs grand unification
NASA Astrophysics Data System (ADS)
Furui, Atsushi; Hosotani, Yutaka; Yamatsu, Naoki
2016-09-01
The SO(11) gauge-Higgs grand unification in the Randall-Sundrum warped space is presented. The 4D Higgs field is identified as the zero mode of the fifth-dimensional component of the gauge potentials, or as the fluctuation mode of the Aharonov-Bohm phase θ along the fifth dimension. Fermions are introduced in the bulk in the spinor and vector representations of SO(11). SO(11) is broken to SO(4)×SO(6) by the orbifold boundary conditions, which is broken to SU2×U1×SU3 by a brane scalar. Evaluating the effective potential V(θ), we show that the electroweak symmetry is dynamically broken to U1. The quark-lepton masses are generated by the Hosotani mechanism and brane interactions, with which the observed mass spectrum is reproduced. Proton decay is forbidden thanks to the new fermion number conservation. It is pointed out that there appear light exotic fermions. The Higgs boson mass is determined with the quark-lepton masses given; however, it turns out to be smaller than the observed value.
Remarks on a Lorentz-breaking 4D chiral gauge theory
NASA Astrophysics Data System (ADS)
Scarpelli, A. P. Baêta; Gomes, M.; Petrov, A. Yu.; da Silva, A. J.
2016-01-01
We investigate a Lorentz-violating chiral model composed of two fermions, a complex scalar field, and a gauge field. We show that, by conveniently adjusting the parameters of the model, it is possible to generate an unambiguous Carroll-Field-Jackiw term and, at the same time, provide the cancellation of the chiral anomaly. The renormalizability of the model is investigated, and it is shown that the same counterterms needed in the symmetric phase also renormalize the model with broken symmetry.
Onofrio, Nicolas; Mouesca, Jean-Marie
2010-05-27
In this paper we aim at presenting a full-VB (valence-bond) analysis of the DFT broken symmetry (BS) exchange coupling constant J(BS). We extend Kahn and Briat's "two sites-two electrons" VB original formalism (Kahn, O.; Briat, B. J. Chem. Soc. Farady Trans. II, 1976, 72, 268) by taking into account the covalent-ionic singlet state mixing, here translated into intersite magnetic orbital delocalization. In this way, two explicit contributions to the magnetic orbital overlap appear, one from the purely covalent state, and the other one from the covalent-ionic mixing. This scheme allows us to relax the strict orthogonality constraint of Kahn and Briat's chemically heuristic model resulting into ferromagnetism. Moreover, we show how DFT-BS calculations applied to various copper(II) dimers yield effective parameters that can be injected into the full-VB model, allowing for a breaking down of J(BS) into various contributions, one of which being either ferromagnetic or antiferromagnetic depending on the bridging ligand topology. Two classes of systems emerge from this analysis and the exceptional ferromagnetic coupling property of the "end-on" azido-bridged copper dimer is especially emphasized.
Exact BPS domain walls at finite gauge coupling
NASA Astrophysics Data System (ADS)
Blaschke, Filip
2017-01-01
Bogomol'nyi-Prasad-Sommerfield solitons in models with spontaneously broken gauge symmetry have been intensively studied at the infinite gauge coupling limit, where the governing equation-the so-called master equation-is exactly solvable. Except for a handful of special solutions, the standing impression is that analytic results at finite coupling are generally unavailable. The aim of this paper is to demonstrate, using domain walls in Abelian-Higgs models as the simplest example, that exact solitons at finite gauge coupling can be readily obtained if the number of Higgs fields (N) is large enough. In particular, we present a family of exact solutions, describing N domain walls at arbitrary positions in models with at least N≥2N+1. We have also found that adding together any pair of solutions can produce a new exact solution if the combined tension is below a certain limit.
Benini, Francesco; Dymarsky, Anatoly; Franco, Sebastian; Kachru, Shamit; Simic, Dusan; Verlinde, Herman; /Princeton, Inst. Advanced Study
2009-06-19
We discuss gravitational backgrounds where supersymmetry is broken at the end of a warped throat, and the SUSY-breaking is transmitted to the Standard Model via gauginos which live in (part of) the bulk of the throat geometry. We find that the leading effect arises from splittings of certain 'messenger mesons,' which are adjoint KK-modes of the D-branes supporting the Standard Model gauge group. This picture is a gravity dual of a strongly coupled field theory where SUSY is broken in a hidden sector and transmitted to the Standard Model via a relative of semi-direct gauge mediation.
The algebra of physical observables in non-linearly realized gauge theories
NASA Astrophysics Data System (ADS)
Quadri, Andrea
2010-11-01
We classify the physical observables in spontaneously broken non-linearly realized gauge theories in the recently proposed loopwise expansion governed by the Weak Power-Counting (WPC) and the Local Functional Equation. The latter controls the non-trivial quantum deformation of the classical non-linearly realized gauge symmetry, to all orders in the loop expansion. The Batalin-Vilkovisky (BV) formalism is used. We show that the dependence of the vertex functional on the Goldstone fields is obtained via a canonical transformation w.r.t. the BV bracket associated with the BRST symmetry of the model. We also compare the WPC with strict power-counting renormalizability in linearly realized gauge theories. In the case of the electroweak group we find that the tree-level Weinberg relation still holds if power-counting renormalizability is weakened to the WPC condition.
Some General Thoughts about Broken Symmetry.
1981-01-21
Higgs boson excitations, the long-range elastic-like forces (such as Suhl-Nakamura interactions in magnets) but most important of all the property I call...parameter is also a constant of the motion, which has important consequences for the nature of the relevant Goldstone bosons . It is too bad that in
... Room? What Happens in the Operating Room? Broken Bones KidsHealth > For Kids > Broken Bones Print A A ... sticking through the skin . What Happens When a Bone Breaks? It hurts to break a bone! It's ...
NASA Astrophysics Data System (ADS)
Brading, Katherine; Castellani, Elena
2010-01-01
Preface; Copyright acknowledgements; List of contributors; 1. Introduction; Part I. Continuous Symmetries: 2. Classic texts: extracts from Weyl and Wigner; 3. Review paper: On the significance of continuous symmetry to the foundations of physics C. Martin; 4. The philosophical roots of the gauge principle: Weyl and transcendental phenomenological idealism T. Ryckman; 5. Symmetries and Noether's theorems K. A. Brading and H. R. Brown; 6. General covariance, gauge theories, and the Kretschmann objection J. Norton; 7. The interpretation of gauge symmetry M. Redhead; 8. Tracking down gauge: an ode to the constrained Hamiltonian formalism J. Earman; 9. Time-dependent symmetries: the link between gauge symmetries and indeterminism D. Wallace; 10. A fourth way to the Aharanov-Bohm effect A. Nounou; Part II. Discrete Symmetries: 11. Classic texts: extracts from Lebniz, Kant and Black; 12. Review paper: Understanding permutation symmetry S. French and D. Rickles; 13. Quarticles and the identity of discernibles N. Hugget; 14. Review paper: Handedness, parity violation, and the reality of space O. Pooley; 15. Mirror symmetry: what is it for a relational space to be orientable? N. Huggett; 16. Physics and Leibniz's principles S. Saunders; Part III. Symmetry Breaking: 17: Classic texts: extracts from Curie and Weyl; 18. Extract from G. Jona-Lasinio: Cross-fertilization in theoretical physics: the case of condensed matter and particle physics G. Jona-Lasinio; 19. Review paper: On the meaning of symmetry breaking E. Castellani; 20. Rough guide to spontaneous symmetry breaking J. Earman; 21. Spontaneous symmetry breaking: theoretical arguments and philosophical problems M. Morrison; Part IV. General Interpretative Issues: 22. Classic texts: extracts from Wigner; 23. Symmetry as a guide to superfluous theoretical structure J. Ismael and B. van Fraassen; 24. Notes on symmetries G. Belot; 25. Symmetry, objectivity, and design P. Kosso; 26. Symmetry and equivalence E. Castellani.
Confinement and flavor symmetry breaking via monopolecondensation
Murayama, Hitoshi
2000-09-19
We discuss dynamics of N=2 supersymmetric SU(n_c) gaugetheories with n_f quark hypermultiplets. Upon N=1 perturbation ofintroducing a finite mass for the adjoint chiral multiplet, we show thatthe flavor U(n_f) symmetry is dynamically broken to U(r) times U(n_f-r),where r\\leq [n_f/2]is an integer. This flavor symmetry breaking occursdue to the condensates of magnetic degrees of freedom which acquireflavor quantum numbers due to the quark zero modes. We briefly comment onthe USp(2n_c) gauge theories. This talk is based on works with GiuseppeCarlino and Ken Konishi, hep-th/0001036 and hep-th/0005076.
Dynamical supersymmetry breaking and late-time R symmetry breaking as the origin of cosmic inflation
NASA Astrophysics Data System (ADS)
Schmitz, Kai; Yanagida, Tsutomu T.
2016-10-01
Spontaneously broken supersymmetry (SUSY) and a vanishingly small cosmological constant imply that R symmetry must be spontaneously broken at low energies. Based on this observation, we suppose that, in the sector responsible for low-energy R symmetry breaking, a discrete R symmetry remains preserved at high energies and only becomes dynamically broken at relatively late times in the cosmological evolution, i.e., after the dynamical breaking of SUSY. Prior to R symmetry breaking, the Universe is then bound to be in a quasi-de Sitter phase—which offers a dynamical explanation for the occurrence of cosmic inflation. This scenario yields a new perspective on the interplay between SUSY breaking and inflation, which neatly fits into the paradigm of high-scale SUSY: inflation is driven by the SUSY-breaking vacuum energy density, while the chiral field responsible for SUSY breaking, the Polonyi field, serves as the inflaton. Because R symmetry is broken only after inflation, slow-roll inflation is not spoiled by otherwise dangerous gravitational corrections in supergravity. We illustrate our idea by means of a concrete example, in which both SUSY and R symmetry are broken by strong gauge dynamics and in which late-time R symmetry breaking is triggered by a small inflaton field value. In this model, the scales of inflation and SUSY breaking are unified, the inflationary predictions are similar to those of F-term hybrid inflation in supergravity, reheating proceeds via gravitino decay at temperatures consistent with thermal leptogenesis, and the sparticle mass spectrum follows from pure gravity mediation. Dark matter consists of thermally produced winos with a mass in the TeV range.
Broken Scale Invariance and Anomalous Dimensions
DOE R&D Accomplishments Database
Wilson, K. G.
1970-05-01
Mack and Kastrup have proposed that broken scale invariance is a symmetry of strong interactions. There is evidence from the Thirring model and perturbation theory that the dimensions of fields defined by scale transformations will be changed by the interaction from their canonical values. We review these ideas and their consequences for strong interactions.
BOOK REVIEW: Symmetry Breaking
NASA Astrophysics Data System (ADS)
Ryder, L. H.
2005-11-01
One of the most fruitful and enduring advances in theoretical physics during the last half century has been the development of the role played by symmetries. One needs only to consider SU(3) and the classification of elementary particles, the Yang Mills enlargement of Maxwell's electrodynamics to the symmetry group SU(2), and indeed the tremendous activity surrounding the discovery of parity violation in the weak interactions in the late 1950s. This last example is one of a broken symmetry, though the symmetry in question is a discrete one. It was clear to Gell-Mann, who first clarified the role of SU(3) in particle physics, that this symmetry was not exact. If it had been, it would have been much easier to discover; for example, the proton, neutron, Σ, Λ and Ξ particles would all have had the same mass. For many years the SU(3) symmetry breaking was assigned a mathematical form, but the importance of this formulation fell away when the quark model began to be taken seriously; the reason the SU(3) symmetry was not exact was simply that the (three, in those days) quarks had different masses. At the same time, and in a different context, symmetry breaking of a different type was being investigated. This went by the name of `spontaneous symmetry breaking' and its characteristic was that the ground state of a given system was not invariant under the symmetry transformation, though the interactions (the Hamiltonian, in effect) was. A classic example is ferromagnetism. In a ferromagnet the atomic spins are aligned in one direction only—this is the ground state of the system. It is clearly not invariant under a rotation, for that would change the ground state into a (similar but) different one, with the spins aligned in a different direction; this is the phenomenon of a degenerate vacuum. The contribution of the spin interaction, s1.s2, to the Hamiltonian, however, is actually invariant under rotations. As Coleman remarked, a little man living in a ferromagnet would
Han Du, Wen-Ge; Götz, Andreas W; Yang, Longhua; Walker, Ross C; Noodleman, Louis
2016-08-21
Broken-symmetry density functional calculations have been performed on the [Fea3, CuB] dinuclear center (DNC) of ba3 cytochrome c oxidase from Thermus thermophilus in the states of [Fea3(3+)-(HO2)(-)-CuB(2+), Tyr237(-)] and [Fea3(4+)[double bond, length as m-dash]O(2-), OH(-)-CuB(2+), Tyr237˙], using both PW91-D3 and OLYP-D3 functionals. Tyr237 is a special tyrosine cross-linked to His233, a ligand of CuB. The calculations have shown that the DNC in these states strongly favors the protonation of His376, which is above propionate-A, but not of the carboxylate group of propionate-A. The energies of the structures obtained by constrained geometry optimizations along the O-O bond cleavage pathway between [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] and [Fea3(4+)[double bond, length as m-dash]O(2-)HO(-)-CuB(2+), Tyr237˙] have also been calculated. The transition of [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] → [Fea3(4+)[double bond, length as m-dash]O(2-)HO(-)-CuB(2+), Tyr237˙] shows a very small barrier, which is less than 3.0/2.0 kcal mol(-1) in PW91-D3/OLYP-D3 calculations. The protonation state of His376 does not affect this O-O cleavage barrier. The rate limiting step of the transition from state A (in which O2 binds to Fea3(2+)) to state PM ([Fea3(4+)[double bond, length as m-dash]O(2-), OH(-)-CuB(2+), Tyr237˙], where the O-O bond is cleaved) in the catalytic cycle is, therefore, the proton transfer originating from Tyr237 to O-O to form the hydroperoxo [Fea3(3+)-(O-OH)(-)-CuB(2+), Tyr237(-)] state. The importance of His376 in proton uptake and the function of propionate-A/neutral-Asp372 as a gate to prevent the proton from back-flowing to the DNC are also shown.
NASA Technical Reports Server (NTRS)
Stecker, F. W.; Brown, R. W.
1979-01-01
Grand unified theories (GUT) such as SU(5), with spontaneous symmetry breaking, can lead more naturally to a globally baryon symmetric big bang cosmology with a domain structure than to a totally asymmetric cosmology. The symmetry is broken at random in causally independent domains, favoring neither a baryon nor an antibaryon excess on a universal scale. Because of the additional freedom in the high-energy physics allowed by such GUT gauge theories, new observational tests may be possible. Arguments in favor of this cosmology and various observational tests are discussed.
BRST symmetry in the Schrödinger picture
NASA Astrophysics Data System (ADS)
Lee, Hyuk-Jae; Yee, Jae Hyung
1993-05-01
We show that the effective Lagrangian including the gauge-fixing and ghost terms of the non-Abelian gauge theories can be derived in the functional Schrödinger picture by using the residual symmetry of the gauge-fixed Lagrangian. This residual gauge symmetry is shown to be equivalent to the well-known Becchi-Rouet-Stora-Tyutin symmetry.
Hak, David J; McElvany, Matthew
2008-02-01
Despite advances in metallurgy, fatigue failure of hardware is common when a fracture fails to heal. Revision procedures can be difficult, usually requiring removal of intact or broken hardware. Several different methods may need to be attempted to successfully remove intact or broken hardware. Broken intramedullary nail cross-locking screws may be advanced out by impacting with a Steinmann pin. Broken open-section (Küntscher type) intramedullary nails may be removed using a hook. Closed-section cannulated intramedullary nails require additional techniques, such as the use of guidewires or commercially available extraction tools. Removal of broken solid nails requires use of a commercial ratchet grip extractor or a bone window to directly impact the broken segment. Screw extractors, trephines, and extraction bolts are useful for removing stripped or broken screws. Cold-welded screws and plates can complicate removal of locked implants and require the use of carbide drills or high-speed metal cutting tools. Hardware removal can be a time-consuming process, and no single technique is uniformly successful.
NASA Astrophysics Data System (ADS)
Teyssandier, Pierre; Tucker, Robin W.
1996-01-01
We discuss the definitions of standard clocks in theories of gravitation. These definitions are motivated by the invariance of actions under different gauge symmetries. We contrast the definition of a standard Weyl clock with that of a clock in general relativity and argue that the historical criticisms of theories based on non-metric compatible connections by Einstein, Pauli and others must be considered in the context of Weyl's original gauge symmetry. We argue that standard Einsteinian clocks can be defined in non-Riemannian theories of gravitation by adopting the Weyl group as a local gauge symmetry that preserves the metric and discuss the hypothesis that atomic clocks may be adopted to measure proper time in the presence of non-Riemannian gravitational fields. These ideas are illustrated in terms of a recently developed model of gravitation based on a non-Riemannian spacetime geometry.
Dynamical generation of the Peccei-Quinn scale in gauge mediation
NASA Astrophysics Data System (ADS)
Festuccia, Guido; Opferkuch, Toby; Ubaldi, Lorenzo
2015-07-01
The Peccei-Quinn (PQ) mechanism provides an elegant solution to the strong charge parity (C P ) problem. However astrophysical constraints on axions require the PQ breaking scale to be far higher than the electroweak scale. In supersymmetric models the PQ symmetry can be broken at an acceptable scale if the effective potential for the pseudomodulus in the axion multiplet develops a minimum at large enough field values. In this work we classify systematically hadronic axion models in the context of gauge mediation and study their effective potentials at one loop. We find that some models generate a PQ scale comparable to the messenger scale. Our result may prove useful for constructing full realistic models of gauge mediation that address the strong C P problem. We also comment briefly on the cosmological aspects related to the saxion and axino, and on the quality of the PQ symmetry.
NASA Technical Reports Server (NTRS)
Burow, G. H.
1984-01-01
Safety wire retains pieces of broken tool. Retrieval wire running through shaft of tool used to pull pieces of tool out of hole, should tool break during use. Safety wire concept suitable for pins subject to deflection or breakage.
Contact symmetries and Hamiltonian thermodynamics
Bravetti, A.; Lopez-Monsalvo, C.S.; Nettel, F.
2015-10-15
It has been shown that contact geometry is the proper framework underlying classical thermodynamics and that thermodynamic fluctuations are captured by an additional metric structure related to Fisher’s Information Matrix. In this work we analyse several unaddressed aspects about the application of contact and metric geometry to thermodynamics. We consider here the Thermodynamic Phase Space and start by investigating the role of gauge transformations and Legendre symmetries for metric contact manifolds and their significance in thermodynamics. Then we present a novel mathematical characterization of first order phase transitions as equilibrium processes on the Thermodynamic Phase Space for which the Legendre symmetry is broken. Moreover, we use contact Hamiltonian dynamics to represent thermodynamic processes in a way that resembles the classical Hamiltonian formulation of conservative mechanics and we show that the relevant Hamiltonian coincides with the irreversible entropy production along thermodynamic processes. Therefore, we use such property to give a geometric definition of thermodynamically admissible fluctuations according to the Second Law of thermodynamics. Finally, we show that the length of a curve describing a thermodynamic process measures its entropy production.
Chiral symmetry and chiral-symmetry breaking
Peskin, M.E.
1982-12-01
These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed. (WHK)
NASA Astrophysics Data System (ADS)
Lovelady, Benjamin C.; Wheeler, James T.
2016-04-01
According to the Coleman-Mandula theorem, any gauge theory of gravity combined with an internal symmetry based on a Lie group must take the form of a direct product in order to be consistent with basic assumptions of quantum field theory. However, we show that an alternative gauging of a simple group can lead dynamically to a spacetime with compact internal symmetry. The biconformal gauging of the conformal symmetry of n-dimensional Euclidean space doubles the dimension to give a symplectic manifold. Examining one of the Lagrangian submanifolds in the flat case, we find that in addition to the expected S O (n ) connection and curvature, the solder form necessarily becomes Lorentzian. General coordinate invariance gives rise to an S O (n -1 ,1 ) connection on the spacetime. The principal fiber bundle character of the original S O (n ) guarantees that the two symmetries enter as a direct product, in agreement with the Coleman-Mandula theorem.
NASA Technical Reports Server (NTRS)
2005-01-01
18 May 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows broken-up blocks of sedimentary rock in western Candor Chasma. There are several locations in western Candor that exhibit this pattern of broken rock. The manner in which these landforms were created is unknown; it is possible that there was a landslide or a meteoritic impact that broke up the materials. One attribute that is known: in some of these cases, it seems that the rock was broken and then buried by later sedimentary rocks, before later being exhumed so that they can be seen from orbit today.
Location near: 6.9oS, 75.5oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Winter
Spontaneous breakdown of Lorentz symmetry in scalar QED with higher order derivatives
Polonyi, Janos; Siwek, Alicja
2011-10-15
Scalar QED is studied with higher order derivatives for the scalar-field kinetic energy. A local potential is generated for the gauge field due to the covariant derivatives and the vacuum with nonvanishing expectation value for the scalar field, and the vector potential is constructed in the leading-order saddle-point expansion. This vacuum breaks the global gauge and Lorentz symmetry spontaneously. The unitarity of time evolution is assured in the physical, positive norm subspace, and the linearized equations of motion are calculated. The Goldstone theorem always keeps the radiation field massless. A particular model is constructed where the full set of standard Maxwell equations is recovered on the tree level, thereby relegating the effects of broken Lorentz symmetry to the level of radiative corrections.
Supersymmetric moose models: An extra dimension from a broken deformed conformal field theory
Erlich, Joshua; Anly Tan, Jong
2006-09-15
We find a class of four dimensional deformed conformal field theories which appear extra dimensional when their gauge symmetries are spontaneously broken. The theories are supersymmetric moose models which flow to interacting conformal fixed points at low energies, deformed by superpotentials. Using a-maximization we give strong nonperturbative evidence that the hopping terms in the resulting latticized action are relevant deformations of the fixed-point theories. These theories have an intricate structure of RG flows between conformal fixed points. Our results suggest that at the stable fixed points each of the bulk gauge couplings and superpotential hopping terms is turned on, in favor of the extra-dimensional interpretation of the theory. However, we argue that the higher-dimensional gauge coupling is generically small compared to the size of the extra dimension. In the presence of a brane the topology of the extra dimension is determined dynamically and depends on the numbers of colors and bulk and brane flavors, which suggests phenomenological applications. The RG flows between fixed points in these theories provide a class of tests of Cardy's conjectured a-theorem.
Calculation of the Mass Spectrum and Deconfining Temperature in Non-Abelian Gauge Theory.
NASA Astrophysics Data System (ADS)
Vohwinkel, Claus
1989-03-01
Using a small volume expansion the mass spectrum and deconfining temperature of SU(2) and SU(3) gauge theory are evaluated. Including non-perturbative features by restoring symmetries which were broken in perturbation theory we obtain results which are valid up to intermediate volumes. The mass spectrum obtained is in good agreement with Luscher's small volume expansion in the small-volume limit and with Monte Carlo Data in medium sized volumes. Using asymmetric volumes we are able to derive the deconfining temperature and find a reasonable agreement with Monte Carlo calculations.
Gauge coupling unification and nonequilibrium thermal dark matter.
Mambrini, Yann; Olive, Keith A; Quevillon, Jérémie; Zaldívar, Bryan
2013-06-14
We study a new mechanism for the production of dark matter in the Universe which does not rely on thermal equilibrium. Dark matter is populated from the thermal bath subsequent to inflationary reheating via a massive mediator whose mass is above the reheating scale T(RH). To this end, we consider models with an extra U(1) gauge symmetry broken at some intermediate scale (M(int) ≃ 10(10)-10(12) GeV). We show that not only does the model allow for gauge coupling unification (at a higher scale associated with grand unification) but it can provide a dark matter candidate which is a standard model singlet but charged under the extra U(1). The intermediate scale gauge boson(s) which are predicted in several E6/SO(10) constructions can be a natural mediator between dark matter and the thermal bath. We show that the dark matter abundance, while never having achieved thermal equilibrium, is fixed shortly after the reheating epoch by the relation T(RH)(3)/M(int)(4). As a consequence, we show that the unification of gauge couplings which determines M(int) also fixes the reheating temperature, which can be as high as T(RH) ≃ 10(11) GeV.
Behavior in strong fields of Euclidean gauge theories. II
NASA Astrophysics Data System (ADS)
Haba, Z.
1984-04-01
Functional determinants resulting from functional integration in quantum gauge theories are studied. We derive an expansion around the constant field strength for the (renormalized) spinor determinant detMF in QED. We show that, if the field strength F is large and its derivatives are bounded, then detMF≡exp(-W)~exp(cF2lnF2), where c>0. Hence, the effective action W in (four-dimensional) QED is unbounded from below. Moreover, we prove that exp(-W) is not integrable. A similar result is established in the Yukawa model [detMY~exp(φ4lnφ4)]. We estimate the scalar determinant detMA2 for a non-Abelian gauge field. We show that (like in the Abelian case studied earlier) detMA2=exp[c|F|2ln|F|2+r2(F,DF,DDF)], where c>0 and r2 is bounded by a quadratic form of the gauge-invariant variables |F|, |DF|, and |DDF|. We investigate the effect of gluon self-interaction on the stability of models with broken gauge symmetry G-->H (we discuss in detail the Georgi-Glashow model). We sum up (in an approximation) the contribution of massive gluons to the O(2)-invariant effective action. It is shown that this effective action is bounded from below for slowly varying fields, if the couplings are asymptotically free at the one-loop level.
NASA Astrophysics Data System (ADS)
Ma, Yong-Liang; Harada, Masayasu; Lee, Hyun Kyu; Oh, Yongseok; Park, Byung-Yoon; Rho, Mannque
2014-08-01
We find that, when the dilaton is implemented as a (pseudo-)Nambu-Goldstone boson using a conformal compensator or "conformon" in a hidden gauge symmetric Lagrangian written to O(p4) from which baryons arise as solitons, namely, skyrmions, the vector manifestation and chiral symmetry restoration at high density predicted in hidden local symmetry theory—which is consistent with Brown-Rho scaling—are lost or sent to infinite density. It is shown that they can be restored if in medium the behavior of the ω field is taken to deviate from that of the ρ meson in such a way that the flavor U(2) symmetry is strongly broken at increasing density. The hitherto unexposed crucial role of the ω meson in the structure of elementary baryon and multibaryon systems is uncovered in this work. In the state of half-skyrmions to which the skyrmions transform at a density n1/2≳n0 (where n0 is the normal nuclear matter density), characterized by the vanishing (space averaged) quark condensate but nonzero pion decay constant, the nucleon mass remains more or less constant at a value ≳60% of the vacuum value, indicating a large component of the nucleon mass that is not associated with the spontaneous breaking of chiral symmetry. We discuss its connection to the chiral-invariant mass m0 that figures in the parity-doublet baryon model.
Nonlinear realization of spontaneously broken N = 1 supersymmetry revisited
NASA Astrophysics Data System (ADS)
Luo, Hui; Luo, Mingxing; Wang, Liucheng
2010-02-01
This paper revisits the nonlinear realization of spontaneously broken N = 1 supersymmetry. It is shown that the constrained superfield formalism as proposed in [6] can be reinterpreted in the language of standard realization of nonlinear supersymmetry via a new and simpler route. Explicit formulas of actions are presented for general renormalizable theories with or without gauge interactions. The nonlinearWess-Zumino gauge is discussed and relations are pointed out for different definitions of gauge fields. In addition, a general procedure is provided to deal with theories of arbitrary Kahler potentials.
Therkleson, Tessa; Stronach, Shona
2015-01-01
This case describes a combination external treatment for “Broken Heart Syndrome” that includes a lavender footbath, massage using moor extract, and oxalis ointment to the abdomen applied by an Anthroposophic nurse for a specific personality type. Lavender footbaths have been used since ancient times for relaxation and calming, while moor extract has been used medicinally in Europe since the middle ages for warmth and environmental protection. Rhythmical massage using moor extract and oxalis ointment poultice to the abdomen are part of the tradition of Anthroposophic nursing when managing stress induced by emotional and physical trauma. An elderly lady with specific characteristics diagnosed as Broken Heart Syndrome received one treatment a week for 4 weeks given by an Anthroposophic nurse at an integrative medical center. Between treatments, education was given to enable self-treatment in the home. The nursing treatments, each using lavender footbaths, moor extract massage, and oxalis ointment poultice to the abdomen, proved very effect, and no negative effects were reported. External applications need to be considered by nurses caring for specific personality types with Broken Heart Syndrome. PMID:25673580
Gauge-symmetric approach to effective lagrangians: The η' meson from QCD
NASA Astrophysics Data System (ADS)
Damgaard, P. H.; Nielsen, H. B.; Sollacher, R.
1994-02-01
We present a general scheme for extracting effective degrees of freedom from an underlying fundamental lagrangian, through a series of well-defined transformations in the functional integral of the cut-off theory. This is done by introducing collective fields in a gauge-symmetric manner. Through appropriate gauge fixings of this symmetry one can remove long-distance degrees of freedom from the underlying theory, replacing them by the collective fields. Applying this technique to QCD, we set out to extract the long-distance dynamics in the pseudoscalar flavour singlet sector through a gauging (and subsequent gauge fixing) of the U (1) A flavour symmetry which is broken by the anomaly. By this series of exact transformations of a cut-off generating functional for QCD, we arrive at a theory describing the long-distance physics of a pseudoscalar flavour singlet meson coupled to the residual quark-gluon degrees of freedom. As an example we show how to derive a Witten-Veneziano-like relation between the η' mass and the topological susceptibility. The resulting effective lagrangian contains an axial vector field, which shares the relevant features with the Veneziano ghost. This field is responsible for removing the η' degree of freedom from the fundamental QCD lagrangian.
Raduta, C. M.; Raduta, A. A.
2010-12-15
A many-body Hamiltonian involving the mean field for a projected spherical single-particle basis, the pairing interactions for alike nucleons, and the dipole-dipole proton-neutron interactions in the particle-hole (ph) channel and the ph dipole pairing potential is treated by the projected gauge fully renormalized proton-neutron quasiparticle random phase approximation approach. The resulting wave functions and energies for the mother and daughter nuclei are used to calculate the 2{nu}{beta}{beta} decay rate and the process half-life. For illustration, the formalism is applied for the decay {sup 100}Mo{yields}{sup 100}Ru. The calculated half-life is in agreement with the corresponding experimental data. The Ikeda sum rule is obeyed.
Non-abelian gauge fields and topological insulators in shaken optical lattices.
Hauke, Philipp; Tieleman, Olivier; Celi, Alessio; Olschläger, Christoph; Simonet, Juliette; Struck, Julian; Weinberg, Malte; Windpassinger, Patrick; Sengstock, Klaus; Lewenstein, Maciej; Eckardt, André
2012-10-05
Time-periodic driving like lattice shaking offers a low-demanding method to generate artificial gauge fields in optical lattices. We identify the relevant symmetries that have to be broken by the driving function for that purpose and demonstrate the power of this method by making concrete proposals for its application to two-dimensional lattice systems: We show how to tune frustration and how to create and control band touching points like Dirac cones in the shaken kagome lattice. We propose the realization of a topological and a quantum spin Hall insulator in a shaken spin-dependent hexagonal lattice. We describe how strong artificial magnetic fields can be achieved for example in a square lattice by employing superlattice modulation. Finally, exemplified on a shaken spin-dependent square lattice, we develop a method to create strong non-abelian gauge fields.
Spontaneous Breaking of Scale Invariance in U(N) Chern-Simons Gauge Theories in Three Dimensions
Bardeen, William
2014-10-24
I explore the existence of a massive phase in a conformally invariant U(N) Chern-Simons gauge theories in D = 3 with matter fields in the fundamental representation. These models have attracted recent attention as being dual, in the conformal phase, to theories of higher spin gravity on AdS 4. Using the 1t Hooft large N expansion, exact solutions are obtained for scalar current correlators in the massive phase where the conformal symmetry is spontaneously broken. A massless dilaton appears as a composite state, and its properties are discussed. Solutions exist for matters field that are either bosons or fermions.
Spontaneous Breaking of Scale Invariance in U(N) Chern-Simons Gauge Theories in Three Dimensions
Bardeen, William A.
2015-09-24
I explore the existence of a massive phase in a conformally invariant U(N) Chern-Simons gauge theories in D = 3 with matter fields in the fundamental representation. These models have attracted recent attention as being dual, in the conformal phase, to theories of higher spin gravity on AdS 4. Using the 0t Hooft large N expansion, exact solutions are obtained for scalar current correlators in the massive phase where the conformal symmetry is spontaneously broken. A massless dilaton appears as a composite state, and its properties are discussed. Solutions exist for matters field that are either bosons or fermions.
Broken current anomalous dimensions, conformal manifolds, and renormalization group flows
NASA Astrophysics Data System (ADS)
Bashmakov, Vladimir; Bertolini, Matteo; Raj, Himanshu
2017-03-01
We consider deformations of a conformal field theory that explicitly break some global symmetries of the theory. If the deformed theory is still a conformal field theory, one can exploit the constraints put by conformal symmetry to compute broken currents anomalous dimensions. We consider several instances of this scenario, using field theory techniques and also holographic ones, where necessary. Field theoretical methods suffice to discuss examples of symmetry-breaking deformations of the O (N ) model in d =4 -ɛ dimensions. Holography is instrumental, instead, for computing current anomalous dimensions in β -deformed superconformal field theories and in a class of supersymmetric renormalization group flows at large N .
Gauge invariants and correlators in flavoured quiver gauge theories
NASA Astrophysics Data System (ADS)
Mattioli, Paolo; Ramgoolam, Sanjaye
2016-10-01
In this paper we study the construction of holomorphic gauge invariant operators for general quiver gauge theories with flavour symmetries. Using a characterisation of the gauge invariants in terms of equivalence classes generated by permutation actions, along with representation theory results in symmetric groups and unitary groups, we give a diagonal basis for the 2-point functions of holomorphic and anti-holomorphic operators. This involves a generalisation of the previously constructed Quiver Restricted Schur operators to the flavoured case. The 3-point functions are derived and shown to be given in terms of networks of symmetric group branching coefficients. The networks are constructed through cutting and gluing operations on the quivers.
Cosmological Solutions in a Spontaneously Broken Gauge Theory
NASA Astrophysics Data System (ADS)
Brihaye, Yves; Hartmann, Betti; Radu, Eugen
2006-02-01
We consider solutions of the Yang-Mills-Higgs system coupled to gravity in asymptotically de Sitter space-time. The basic features of two classes of solutions are discussed, one of them corresponding to magnetic monopoles, the other one to sphalerons. We find that although the total mass within the cosmological horizon of these configurations is finite, their mass evaluated at timelike infinity generically diverges for most values of the cosmological constant. Also, no solutions exist in the absence of a Higgs potential.
Spontaneous Breaking of Lie Groups to Discrete Symmetries
NASA Astrophysics Data System (ADS)
Rachlin, Bradley; Kephart, Thomas
2017-01-01
Many models of beyond Standard Model physics connect flavor symmetry with a discrete group. Having this symmetry arise spontaneously from a gauge theory maintains compatibility with quantum gravity and prevents anomalies. We detail ways to set up Higgs potentials to break gauge groups to discrete symmetries of interest. The scalar mass spectra are examined. Research Assistantship funded by Department of Energy (DOE).
Dynamical Messengers for Gauge Mediation
Hook, Anson; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept.
2011-08-17
We construct models of indirect gauge mediation where the dynamics responsible for breaking supersymmetry simultaneously generates a weakly coupled subsector of messengers. This provides a microscopic realization of messenger gauge mediation where the messenger and hidden sector fields are unified into a single sector. The UV theory is SQCD with massless and massive quarks plus singlets, and at low energies it flows to a weakly coupled quiver gauge theory. One node provides the primary source of supersymmetry breaking, which is then transmitted to the node giving rise to the messenger fields. These models break R-symmetry spontaneously, produce realistic gaugino and sfermion masses, and give a heavy gravitino.
Generalized gaugino condensation in super Yang-Mills theories: Discrete R symmetries and vacua
NASA Astrophysics Data System (ADS)
Kehayias, John
2010-12-01
One can define generalized models of gaugino condensation as theories that dynamically break a discrete R symmetry but do not break supersymmetry. We consider general examples consisting of gauge and matter fields and the minimal number of gauge-singlet fields to avoid flat directions in the potential. We explore which R symmetries can arise and their spontaneous breaking. In general, we find that the discrete symmetry is Z2b0R, and the number of supersymmetric vacua is b0, where b0 is the coefficient of the one-loop beta function. Results are presented for various groups, including SU(Nc), SO(Nc), Sp(2Nc), and G2, for various numbers of flavors, Nf, by several methods. This analysis can also apply to the other exceptional groups and, thus, all simple Lie groups. We also comment on model-building applications where a discrete R symmetry, broken by the singlet vacuum expectation values, can account for μ-type terms and allow a realistic Higgs spectrum naturally.
Gauge natural formulation of conformal gravity
Campigotto, M.; Fatibene, L.
2015-03-15
We consider conformal gravity as a gauge natural theory. We study its conservation laws and superpotentials. We also consider the Mannheim and Kazanas spherically symmetric vacuum solution and discuss conserved quantities associated to conformal and diffeomorphism symmetries.
NASA Astrophysics Data System (ADS)
Field, R. W.; Park, G. B.; Changala, P. B.; Baraban, J. H.; Stanton, J. F.; Merer, A. J.
2013-06-01
Spectroscopy - it is all about patterns. Some patterns look so indescribably complicated that, unlike pornography, you do not know one when you see one. It is tempting to say that, at high vibrational excitation, interactions among normal mode basis states are so strong and widespread that all patterns are obliterated. But this is not true. When normal mode frequencies are in near integer multiple ratios, polyads emerge. A polyad is a robust pattern often comprising many vibrational eigenstates. Each such pattern might span many hundreds of cm^{-1}, and it is inevitable that several unrelated polyad patterns overlap. When polyads overlap, it might seem impossible to disentangle them. However, the key to disentanglement is that polyads come in families in which successive generations are related by harmonic oscillator matrix element selection and scaling rules. Families of polyads are described by families of scaling-based effective Hamiltonian matrices, {H}^{{eff}}. No matter how complex and overlapped, the polyad {H}^{{eff}} serves as a magic decoder for picking out the polyad pattern. Sometimes the polyad patterns are systematically broken (a meta-pattern), owing to proximity to an isomerization barrier, as occurs in highly excited bending levels of the S_{1} state of HCCH, which encode the trans-cis minimum energy isomerization path. Quantum Chemists often dismiss {H}^{{eff}} models, precisely because they are models that do not express the full dimensionality of the complete Hamiltonian. But an {H}^{{eff}} explains rather than describes. Shunning {H}^{{eff}}s is like throwing out the baby with the bath water. Don't do it!
Supersymmetry Breaking and Gauge Mediation
NASA Astrophysics Data System (ADS)
Kitano, Ryuichiro; Ooguri, Hirosi; Ookouchi, Yutaka
2010-11-01
We review recent works on supersymmetry breaking and gauge mediation. We survey our current understanding of dynamical supersymmetry-breaking mechanisms and describe new model-building tools that use duality, metastability, and stringy construction. We discuss phenomenological constraints and their solutions, paying particular attention to gaugino masses and electroweak symmetry breaking.
Broken Bones, Sprains, and Strains (For Parents)
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Digital lattice gauge theories
NASA Astrophysics Data System (ADS)
Zohar, Erez; Farace, Alessandro; Reznik, Benni; Cirac, J. Ignacio
2017-02-01
We propose a general scheme for a digital construction of lattice gauge theories with dynamical fermions. In this method, the four-body interactions arising in models with 2 +1 dimensions and higher are obtained stroboscopically, through a sequence of two-body interactions with ancillary degrees of freedom. This yields stronger interactions than the ones obtained through perturbative methods, as typically done in previous proposals, and removes an important bottleneck in the road towards experimental realizations. The scheme applies to generic gauge theories with Lie or finite symmetry groups, both Abelian and non-Abelian. As a concrete example, we present the construction of a digital quantum simulator for a Z3 lattice gauge theory with dynamical fermionic matter in 2 +1 dimensions, using ultracold atoms in optical lattices, involving three atomic species, representing the matter, gauge, and auxiliary degrees of freedom, that are separated in three different layers. By moving the ancilla atoms with a proper sequence of steps, we show how we can obtain the desired evolution in a clean, controlled way.
NASA Astrophysics Data System (ADS)
Weisz, Peter; Majumdar, Pushan
2012-03-01
Lattice gauge theory is a formulation of quantum field theory with gauge symmetries on a space-time lattice. This formulation is particularly suitable for describing hadronic phenomena. In this article we review the present status of lattice QCD. We outline some of the computational methods, discuss some phenomenological applications and a variety of non-perturbative topics. The list of references is severely incomplete, the ones we have included are text books or reviews and a few subjectively selected papers. Kronfeld and Quigg (2010) supply a reasonably comprehensive set of QCD references. We apologize for the fact that have not covered many important topics such as QCD at finite density and heavy quark effective theory adequately, and mention some of them only in the last section "In Brief". These topics should be considered in further Scholarpedia articles.
Broken Symmetry and Coherent Structure in MHD Turbulence
NASA Technical Reports Server (NTRS)
Shebalin, John V.
2007-01-01
Absolute equilibrium ensemble theory for ideal homogeneous magnetohydrodynamic (MHD) turbulence is fairly well developed. Theory and Simulation indicate that ideal MHD turbulence non-ergodic and contains coherent structure. The question of applicability real (i.e., dissipative) MHD turbulence is examined. Results from several very long time numerical simulations on a 64(exp 3) grid are presented. It is seen that coherent structure begins to form before decay dominates over nonlinearity. The connection with inverse spectral cascades and selective decay will also be discussed.
Vacuum stability and radiative electroweak symmetry breaking in an SO(10) dark matter model
NASA Astrophysics Data System (ADS)
Mambrini, Yann; Nagata, Natsumi; Olive, Keith A.; Zheng, Jiaming
2016-06-01
Vacuum stability in the Standard Model is problematic as the Higgs quartic self-coupling runs negative at a renormalization scale of about 1010 GeV . We consider a nonsupersymmetric SO(10) grand unification model for which gauge coupling unification is made possible through an intermediate scale gauge group, Gint=SU (3 )C⊗SU (2 )L⊗SU (2 )R⊗U (1 )B -L . Gint is broken by the vacuum expectation value of a 126 of SO(10) which not only provides for neutrino masses through the seesaw mechanism but also preserves a discrete Z2 that can account for the stability of a dark matter candidate, here taken to be the Standard Model singlet component of a bosonic 16 . We show that in addition to these features the model insures the positivity of the Higgs quartic coupling through its interactions to the dark matter multiplet and 126 . We also show that the Higgs mass squared runs negative, triggering electroweak symmetry breaking. Thus, the vacuum stability is achieved along with radiative electroweak symmetry breaking and captures two more important elements of supersymmetric models without low-energy supersymmetry. The conditions for perturbativity of quartic couplings and for radiative electroweak symmetry breaking lead to tight upper and lower limits on the dark matter mass, respectively, and this dark matter mass region (1.35-2 TeV) can be probed in future direct detection experiments.
Optical Abelian lattice gauge theories
Tagliacozzo, L.; Celi, A.; Zamora, A.; Lewenstein, M.
2013-03-15
We discuss a general framework for the realization of a family of Abelian lattice gauge theories, i.e., link models or gauge magnets, in optical lattices. We analyze the properties of these models that make them suitable for quantum simulations. Within this class, we study in detail the phases of a U(1)-invariant lattice gauge theory in 2+1 dimensions, originally proposed by P. Orland. By using exact diagonalization, we extract the low-energy states for small lattices, up to 4 Multiplication-Sign 4. We confirm that the model has two phases, with the confined entangled one characterized by strings wrapping around the whole lattice. We explain how to study larger lattices by using either tensor network techniques or digital quantum simulations with Rydberg atoms loaded in optical lattices, where we discuss in detail a protocol for the preparation of the ground-state. We propose two key experimental tests that can be used as smoking gun of the proper implementation of a gauge theory in optical lattices. These tests consist in verifying the absence of spontaneous (gauge) symmetry breaking of the ground-state and the presence of charge confinement. We also comment on the relation between standard compact U(1) lattice gauge theory and the model considered in this paper. - Highlights: Black-Right-Pointing-Pointer We study the quantum simulation of dynamical gauge theories in optical lattices. Black-Right-Pointing-Pointer We focus on digital simulation of abelian lattice gauge theory. Black-Right-Pointing-Pointer We rediscover and discuss the puzzling phase diagram of gauge magnets. Black-Right-Pointing-Pointer We detail the protocol for time evolution and ground-state preparation in any phase. Black-Right-Pointing-Pointer We provide two experimental tests to validate gauge theory quantum simulators.
Betts, Robert E.; Crawford, John F.
1989-01-01
An aging gauge comprising a container having a fixed or a variable sized t opening with a cap which can be opened to control the sublimation rate of a thermally sublimational material contained within the container. In use, the aging gauge is stored with an item to determine total heat the item is subjected to and also the maximum temperature to which the item has been exposed. The aging gauge container contains a thermally sublimational material such as naphthalene or similar material which has a low sublimation rate over the temperature range from about 70.degree. F. to about 160.degree. F. The aging products determined by analyses of a like item aged along with the aging gauge for which the sublimation amount is determined is employed to establish a calibration curve for future aging evaluation. The aging gauge is provided with a means for determining the maximum temperature exposure (i.e., a thermally indicating material which gives an irreversible color change, Thermocolor pigment). Because of the relationship of doubling reaction rates for increases of 10.degree. C., equivalency of item used in accelerated aging evaluation can be obtained by referring to a calibration curve depicting storage temperature on the abscissa scale and multiplier on the ordinate scale.
Betts, Robert E.; Crawford, John F.
1989-04-04
An aging gauge comprising a container having a fixed or a variable sized t opening with a cap which can be opened to control the sublimation rate of a thermally sublimational material contained within the container. In use, the aging gauge is stored with an item to determine total heat the item is subjected to and also the maximum temperature to which the item has been exposed. The aging gauge container contains a thermally sublimational material such as naphthalene or similar material which has a low sublimation rate over the temperature range from about 70.degree. F. to about 160.degree. F. The aging products determined by analyses of a like item aged along with the aging gauge for which the sublimation amount is determined is employed to establish a calibration curve for future aging evaluation. The aging gauge is provided with a means for determining the maximum temperature exposure (i.e., a thermally indicating material which gives an irreversible color change, Thermocolor pigment). Because of the relationship of doubling reaction rates for increases of 10.degree. C., equivalency of item used in accelerated aging evaluation can be obtained by referring to a calibration curve depicting storage temperature on the abscissa scale and multiplier on the ordinate scale.
Cartan gravity, matter fields, and the gauge principle
Westman, Hans F.; Zlosnik, Tom G.
2013-07-15
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 of 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
Personal recollections on chiral symmetry breaking
NASA Astrophysics Data System (ADS)
Kobayashi, Makoto
2016-07-01
The author's work on the mass of pseudoscalar mesons is briefly reviewed. The emergence of the study of CP violation in the renormalizable gauge theory from consideration of chiral symmetry in the quark model is discussed.
Harada–Tsutsui gauge recovery procedure: From Abelian gauge anomalies to the Stueckelberg mechanism
Lima, Gabriel Di Lemos Santiago
2014-02-15
Revisiting a path-integral procedure developed by Harada and Tsutsui for recovering gauge invariance from anomalous effective actions, it is shown that there are two ways to achieve gauge symmetry: one already presented by the authors, which is shown to preserve the anomaly in the sense of standard current conservation law, and another one which is anomaly-free, preserving current conservation. It is also shown that the application of the Harada–Tsutsui technique to other models which are not anomalous but do not exhibit gauge invariance allows the identification of the gauge invariant formulation of the Proca model, also done by the referred authors, with the Stueckelberg model, leading to the interpretation of the gauge invariant map as a generalization of the Stueckelberg mechanism. -- Highlights: • A gauge restoration technique from Abelian anomalous models is discussed. • It is shown that there is another way that leads to gauge symmetry restoration from such technique. • It is shown that the first gauge restoration preserves the anomaly, while the proposed second one is free from anomalies. • It is shown that the proposed gauge symmetry restoration can be identified with the Stueckelberg mechanism.
Symmetry impedes symmetry discrimination.
Tjan, Bosco S; Liu, Zili
2005-12-16
Objects in the world, natural and artificial alike, are often bilaterally symmetric. The visual system is likely to take advantage of this regularity to encode shapes for efficient object recognition. The nature of encoding a symmetric shape, and of encoding any departure from it, is therefore an important matter in visual perception. We addressed this issue of shape encoding empirically, noting that a particular encoding scheme necessarily leads to a specific profile of sensitivity in perceptual discriminations. We studied symmetry discrimination using human faces and random dots. Each face stimulus was a frontal view of a three-dimensional (3-D) face model. The 3-D face model was a linearly weighted average (a morph) between the model of an original face and that of the corresponding mirror face. Using this morphing technique to vary the degree of asymmetry, we found that, for faces and analogously generated random-dot patterns alike, symmetry discrimination was worst when the stimuli were nearly symmetric, in apparent opposition to almost all studies in the literature. We analyzed the previous work and reconciled the old and new results using a generic model with a simple nonlinearity. By defining asymmetry as the minimal difference between the left and right halves of an object, we found that the visual system was disproportionately more sensitive to larger departures from symmetry than to smaller ones. We further demonstrated that our empirical and modeling results were consistent with Weber-Fechner's and Stevens's laws.
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Broken Homes: Impact on Adolescents.
ERIC Educational Resources Information Center
Koziey, Paul W.; Davies, Leigh
1982-01-01
Tends to support assertion that children from homes broken by separation, divorce, or death are less well-adjusted in terms of California Personality Inventory scales of self-control, socialization, femininity, and good impression, than children from intact homes. Age and sex were not found to be linked to the degree of maladjustment. (AH)
ERIC Educational Resources Information Center
Grabowski, Carl
2008-01-01
Taking over a broken program can be one of the hardest tasks to take on. However, working towards a vision and a common goal--and eventually getting there--makes it all worth it in the end. In this article, the author shares the lessons she learned as the new director for the Bright Horizons Center in Ashburn, Virginia. She suggests that new…
Green-Schwarz superstring on doubled-yet-gauged spacetime
NASA Astrophysics Data System (ADS)
Park, Jeong-Hyuck
2016-11-01
We construct a world-sheet action for Green-Schwarz superstring in terms of doubled-yet-gauged spacetime coordinates. For an arbitrarily curved NS-NS background, the action possesses O(10, 10) T-duality, Spin(1, 9) × Spin(9, 1) Lorentz symmetry, coordinate gauge symmetry, spacetime doubled-yet-gauged diffeomorphisms, world-sheet diffeomorphisms and Weyl symmetry. Further, restricted to flat backgrounds, it enjoys maximal spacetime supersymmetry and kappa-symmetry. After the auxiliary coordinate gauge symmetry potential being integrated out, our action can consistently reduce to the original undoubled Green-Schwarz action. Thanks to the twofold spin groups, the action is unique: it is specific choices of the NS-NS backgrounds that distinguish IIA or IIB, as well as lead to non-Riemannian or non-relativistic superstring a la Gomis-Ooguri which might deserve the nomenclature, type IIC.
Light dilaton in walking gauge theories
Appelquist, Thomas; Bai Yang
2010-10-01
We analyze the existence of a dilaton in gauge theories with approximate infrared conformal symmetry. To the extent that these theories are governed in the infrared by an approximate fixed point (walking), the explicit breaking of the conformal symmetry at these scales is vanishingly small. If confinement and spontaneous chiral-symmetry breaking set in at some infrared scale, the resultant breaking of the approximate conformal symmetry can lead to the existence of a dilaton with mass parametrically small compared to the confinement scale, and potentially observable at the LHC.
Gauge-Higgs unification and quark-lepton phenomenology in the warped spacetime
Hosotani, Y.; Noda, S.; Sakamura, Y.; Shimasaki, S.
2006-05-01
In the dynamical gauge-Higgs unification of electroweak interactions in the Randall-Sundrum warped spacetime, the Higgs boson mass is predicted in the range 120-290 GeV, provided that the spacetime structure is determined at the Planck scale. Couplings of quarks and leptons to gauge bosons and their Kaluza-Klein excited states are determined by the masses of quarks and leptons. All quarks and leptons other than top quarks have very small couplings to the Kaluza-Klein excited states of gauge bosons. The universality of weak interactions is slightly broken by magnitudes of 10{sup -8}, 10{sup -6}, and 10{sup -2} for {mu}-e, {tau}-e and t-e, respectively. Yukawa couplings become substantially smaller than those in the standard model, by a factor cos(1/2){theta}{sub W} where {theta}{sub W} is the non-Abelian Aharonov-Bohm phase (the Wilson line phase) associated with dynamical electroweak symmetry breaking.
Gauge formulation of gravitation theories. I. The Poincaré, de Sitter, and conformal cases
NASA Astrophysics Data System (ADS)
Ivanov, E. A.; Niederle, J.
1982-02-01
The gauge formulations of various gravitation theories are discussed. They are based on the approach in which we have the group Diff R4 acting on xμ and in which we attach to every xμ a tangent space with the group of action H. Group H does not act on xμ and plays the role of an internal (global) symmetry group in the standard Yang-Mills theory. The matter fields in the theory transform according to representations of H and are assumed to be scalars of Diff R4. The full invariance group of the Lagrangian is then of the form Hloc⊗Diff R4. Here Hloc is a local gauge group obtained from H exactly as in the Yang-Mills theory. The approach has two characteristic features: (i) The group Hloc must be spontaneously broken in order to exclude redundant gauge fields (the Lorentz connections) from the theory in a way covariant with respect to the gauge transformations. (ii) To different H there correspond different gravitational theories, all invariant under Diff R4 but differing in backgrounds. Thus if H is isomorphic to the Poincaré group the corresponding gauge theory turns out to be equivalent to the usual Einstein or Einstein-Cartan theory of gravity in the Minkowski space as a background. The other choices for H considered in the paper are the de Sitter groups and the conformal group. They yield the Einstein theory with a negative (or positive) cosmological term in the corresponding de Sitter space and the Weyl or Cartan-Weyl theory (depending on realization of the conformal group), respectively.
Topological symmetry breaking by quantum wormholes
Mignemi, S.; Moss, I. )
1993-10-15
In multiply connected spacetimes which contain quantum wormholes it may be possible to break gauge symmetries without the usual Higgs fields. In a simple model, symmetry breaking is favored by the quantum effects of Dirac Fermions and leads to vector boson masses related to the wormhole separation.
Electroweak symmetry breaking: Top quard condensates
Bardeen, W.A.
1990-12-01
The fundamental mechanisms for the dynamical breaking of the electroweak gauge symmetries remain a mystery. This paper examines the possible role of heavy fermions, particularly the top quark, in generating the observed electroweak symmetry breaking, the masses of the W and Z bosons and the masses of all observed quarks and leptons. 27 refs., 10 figs., 4 tabs.
A broken E6 solution to the solar neutrino problem
NASA Astrophysics Data System (ADS)
Ross, G. G.; Segrè, G. C.
1987-10-01
Broken E6 models, as suggested by superstrings, may have stable massive neutrinos in matter multiplets. These can be candidates for the dark matter of the universe. If we choose an additional Z' in the E6 gauge multiplet to couple to these neutrinos, but not ordinary leptons, we may also solve the solar neutrino problem, without violating known experimental bounds. The Z' must have a mass comparable to the ordinary Z mass. On sabbatical leave from Department of Physics, University of Pennsylvania, Philadelphia, PA 19104, USA.
Symmetry enrichment in three-dimensional topological phases
NASA Astrophysics Data System (ADS)
Ning, Shang-Qiang; Liu, Zheng-Xin; Ye, Peng
2016-12-01
While two-dimensional symmetry-enriched topological phases (SETs ) have been studied intensively and systematically, three-dimensional ones are still open issues. We propose an algorithmic approach of imposing global symmetry Gs on gauge theories (denoted by GT) with gauge group Gg. The resulting symmetric gauge theories are dubbed "symmetry-enriched gauge theories" (SEG), which may be served as low-energy effective theories of three-dimensional symmetric topological quantum spin liquids. We focus on SEGs with gauge group Gg=ZN1×ZN2×⋯ and onsite unitary symmetry group Gs=ZK1×ZK2×⋯ or Gs=U (1 ) ×ZK 1×⋯ . Each SEG(Gg,Gs) is described in the path-integral formalism associated with certain symmetry assignment. From the path-integral expression, we propose how to physically diagnose the ground-state properties (i.e., SET orders) of SEGs in experiments of charge-loop braidings (patterns of symmetry fractionalization) and the mixed multiloop braidings among deconfined loop excitations and confined symmetry fluxes. From these symmetry-enriched properties, one can obtain the map from SEGs to SETs . By giving full dynamics to background gauge fields, SEGs may be eventually promoted to a set of new gauge theories (denoted by GT*). Based on their gauge groups, GT*s may be further regrouped into different classes, each of which is labeled by a gauge group Gg*. Finally, a web of gauge theories involving GT,SEG,SET, and GT* is achieved. We demonstrate the above symmetry-enrichment physics and the web of gauge theories through many concrete examples.
Symmetries in nuclei: New methods and applications
NASA Astrophysics Data System (ADS)
Caprio, Mark A.
2011-04-01
When a symmetry is a ``good'' symmetry of the nuclear system, as in the dynamical symmetries of the shell model and interacting boson model, this symmetry can directly give the spectroscopic properties of the nucleus, without the need for involved calculations. However, even if a symmetry is strongly broken, it nonetheless provides a calculational tool, classifying the basis states used in a full computational treatment of the many-body problem and greatly simplifying the underlying computational machinery. The symmetry then serves as the foundation for a physically meaningful truncation scheme for the calculation. This talk will provide an introduction to new applications of symmetry approaches to the nuclear problem, including the required mathematical developments. Supported by the US DOE under grant DE-FG02-95ER-40934 and by the Research Corporation for Science Advancement under a Cottrell Scholar Award.
Topological orders with global gauge anomalies
NASA Astrophysics Data System (ADS)
You, Yi-Zhuang; Xu, Cenke
2015-08-01
By definition, the physics of the d -dimensional (dim) boundary of a (d +1 ) -dim symmetry protected topological (SPT) state cannot be realized as itself on a d -dim lattice. If the symmetry of the system is unitary, then a formal way to determine whether a d -dim theory must be a boundary or not, is to couple this theory to a gauge field (or to "gauge" its symmetry), and check if there is a gauge anomaly. In this paper we discuss the following question: Can the boundary of a SPT state be driven into a fully gapped topological order which preserves all the symmetries? We argue (conjecture) that if the gauge anomaly of the boundary is "perturbative," then the boundary must remain gapless; while if the boundary only has global gauge anomaly but no perturbative anomaly, then it is possible to gap out the boundary by driving it into a topological state, when d ≥2 . We will demonstrate this conjecture with two examples: (1) the 3 d spin-1/2 chiral fermion with the well-known Witten's global anomaly [Phys. Lett. 117, 324 (1982), 10.1016/0370-2693(82)90728-6], which can be realized on the boundary of a 4 d topological superconductor with SU(2) or U (1 ) ⋊Z2 symmetry; and (2) the 4 d boundary of a 5 d topological superconductor with the same symmetry. We show that these boundary systems can be driven into a fully gapped Z2 N topological order with topological degeneracy, but this Z2 N topological order cannot be future driven into a trivial confined phase that preserves all the symmetries due to some special properties of its topological defects. Our study also leads to exotic states of matter in pure 3 d space.
NASA Astrophysics Data System (ADS)
Nucci, M. C.
2016-09-01
We review some of our recent work devoted to the problem of quantization with preservation of Noether symmetries, finding hidden linearity in superintegrable systems, and showing that nonlocal symmetries are in fact local. In particular, we derive the Schrödinger equation for the isochronous Calogero goldfish model using its relation to Darwin equation. We prove the linearity of a classical superintegrable system on a plane of nonconstant curvature. We find the Lie point symmetries that correspond to the nonlocal symmetries (also reinterpreted as λ-symmetries) of the Riccati chain.
Renormalization In Quantum Gauge Theory Using Zeta-Function Method
Chiritoiu, Viorel; Zet, Gheorghe
2009-05-22
It is possible to consider space-time symmetries (for example Poincare or de Sitter) as purely inner symmetries. A formulation of the de Sitter symmetry as purely inner symmetry defined on a fixed Minkowski space-time is presented. We define the generators of the de Sitter group and write the equations of structure using a constant deformation parameter {lambda}. Local gauge transformations and corresponding covariant derivative depending on gauge fields are obtained. The method of generalized zeta-function is used to realize the renormalization. An effective integral of action is obtained and a comparison with other results is given.
Gauge-independent Higgs mechanism and the implications for quark confinement
NASA Astrophysics Data System (ADS)
Kondo, Kei-Ichi
2017-03-01
We propose a gauge-invariant description for the Higgs mechanism by which a gauge boson acquires the mass. We do not need to assume spontaneous breakdown of gauge symmetry signaled by a non-vanishing vacuum expectation value of the scalar field. In fact, we give a manifestly gauge-invariant description of the Higgs mechanism in the operator level, which does not rely on spontaneous symmetry breaking. For concreteness, we discuss the gauge-Higgs models with U(1) and SU(2) gauge groups explicitly. This enables us to discuss the confinement-Higgs complementarity from a new perspective.
Identical Wells, Symmetry Breaking, and the Near-Unitary Limit
NASA Astrophysics Data System (ADS)
Harshman, N. L.
2017-03-01
Energy level splitting from the unitary limit of contact interactions to the near unitary limit for a few identical atoms in an effectively one-dimensional well can be understood as an example of symmetry breaking. At the unitary limit in addition to particle permutation symmetry there is a larger symmetry corresponding to exchanging the N! possible orderings of N particles. In the near unitary limit, this larger symmetry is broken, and different shapes of traps break the symmetry to different degrees. This brief note exploits these symmetries to present a useful, geometric analogy with graph theory and build an algebraic framework for calculating energy splitting in the near unitary limit.
Noether's therorem for local gauge transformations
Karatas, D.L.; Kowalski, K.L.
1989-05-22
The variational methods of classical field theory may be applied to any theory with an action which is invariant under local gauge transformations. What is the significance of the resulting Noether current. This paper examines such currents for both Abelian and non-Abelian gauge theories and provides an explanation for their form and limited range of physical significance on a level accessible to those with a basic knowledge of classical field theory. Several of the more subtle aspects encountered in the application of the residual local gauge symmetry found by Becchi, Rouet, Stora, and Tyutin are also considered in detail in a self-contained manner. 23 refs.
Tuning the cosmological constant, broken scale invariance, unitarity
Förste, Stefan; Manz, Paul
2016-06-10
We study gravity coupled to a cosmological constant and a scale but not conformally invariant sector. In Minkowski vacuum, scale invariance is spontaneously broken. We consider small fluctuations around the Minkowski vacuum. At the linearised level we find that the trace of metric perturbations receives a positive or negative mass squared contribution. However, only for the Fierz-Pauli combination the theory is free of ghosts. The mass term for the trace of metric perturbations can be cancelled by explicitly breaking scale invariance. This reintroduces fine-tuning. Models based on four form field strength show similarities with explicit scale symmetry breaking due to quantisation conditions.
Flavor mixing in gauge-Higgs unification
Adachi, Y.; Kurahashi, N.; Lim, C. S.; Maru, N.; Tanabe, K.
2012-07-27
Gauge-Higgs unification is the fascinating scenario solving the hierarchy problem without supersymmetry. In this scenario, the Standard Model (SM) Higgs doublet is identified with extra component of the gauge field in higher dimensions and its mass becomes finite and stable under quantum corrections due to the higher dimensional gauge symmetry. On the other hand, Yukawa coupling is provided by the gauge coupling, which seems to mean that the flavor mixing and CP violation do not arise at it stands. In this talk, we discuss that the flavor mixing is originated from simultaneously non-diagonalizable bulk and brane mass matrices. Then, this mechanism is applied to various flavor changing neutral current (FCNC) processes via Kaluza-Klein (KK) gauge boson exchange at tree level and constraints for compactification scale are obtained.
O'Raifeartaigh models with spontaneous R-symmetry breaking
Ferretti, Luca
2007-11-20
O'Raifeartaigh models with general R-charge assignments can have vacua where both supersymmetry and R-symmetry are spontaneously broken. Most of these vacua are metastable because the potential shows a runaway behaviour. We explain the relation between runaway directions and R-symmetry.
Self-consistent Models of Strong Interaction with Chiral Symmetry
DOE R&D Accomplishments Database
Nambu, Y.; Pascual, P.
1963-04-01
Some simple models of (renormalizable) meson-nucleon interaction are examined in which the nucleon mass is entirely due to interaction and the chiral ( gamma {sub 5}) symmetry is "broken'' to become a hidden symmetry. It is found that such a scheme is possible provided that a vector meson is introduced as an elementary field. (auth)
Parity anomalies in gauge theories in 2 + 1 dimensions
Rao, S.; Yahalom, R.
1986-01-01
We show that the introduction of massless fermions in an abelian gauge theory in 2+1 dimensions does not lead to any parity anomaly despite a non-commutativity of limits in the structure function of the odd part of the vacuum polarization tensor. However, parity anomaly does exist in non-abelian theories due to a conflict between gauge invariance under large gauge transformations and the parity symmetry. 6 refs.
Generalized mixing angles in gauge theories with natural flavor conservation
Rothman, Arthur C.; Kang, Kyungsik
1981-01-01
A number of theorems, relating Natural Flavor Conservation and Calculability are proven for general gauge models of the weak and electromagnetic interactions with an unbroken U(1) symmetry. The concept of nontriviality - a necessary condition that all naturally flavor conserving gauge models must obey in order to have nontrivial mixing angles - is introduced. It is found that naturality groups guaranteeing Natural Flavor Conservation cannot generate meaningful mixing angles in any gauge model.
Strong Electroweak Symmetry Breaking in the Large Hadron Collider Era
NASA Astrophysics Data System (ADS)
Evans, Jared Andrew
2011-12-01
With the Large Hadron Collider collecting data, both the pursuit of novel detection techniques and the exploration of new ideas are more important than ever. Novel detection techniques are essential in order for the community to garner the most worth from the machine. New ideas are needed both to expand the boundaries of what could be observed and to foster the creative mindset of the community that moves particle physics into fascinating, and often unexpected, directions. Discovering whether electroweak symmetry is broken strongly or weakly is one of the most pressing questions to be answered. Exploring the possibility of strong electroweak symmetry breaking is the topic of this work. The first of two major sectors in this work concerns the theory of conformal technicolor. We present the low energy minimal model for conformal technicolor and verify that it can satisfy current constraints from experiment. We will also provide a UV completion for this model, which realistically extends the sector with high-energy supersymmetry. Two complete models of flavor are presented. This is the first example of a complete, consistent model of strong electroweak symmetry breaking. The second of the two sectors discusses experimental signatures arising in a large class of general technicolor models at the Large Hadron Collider. The possible existence of narrow scalar states that can be produced via gluon-gluon fusion is first discussed. These states can decay into exotic final states of multiple electroweak gauge bosons, third generation particles and even light composite Higgs particles. A two Higgs doublet model is proposed as an effective way to model these exciting states. Lastly, we discuss the array of possible final states and their possible discovery.
Unsal, Mithat
2007-03-06
We study the phase diagrams of N = {infinity} vector-like, asymptotically free gauge theories as a function of volume, on S{sup 3} x S{sup 1}. The theories of interest are the ones with fermions in two index representations [adjoint, (anti)symmetric, and bifundamental abbreviated as QCD(adj), QCD(AS/S) and QCD(BF)], and are interrelated via orbifold or orientifold projections. The phase diagrams reveal interesting phenomena such as disentangled realizations of chiral and center symmetry, confinement without chiral symmetry breaking, zero temperature chiral transitions, and in some cases, exotic phases which spontaneously break the discrete symmetries such as C, P, T as well as CPT. In a regime where the theories are perturbative, the deconfinement temperature in SYM, and QCD(AS/S/BF) coincide. The thermal phase diagrams of thermal orbifold QCD(BF), orientifold QCD(AS/S), and N = 1 SYM coincide, provided charge conjugation symmetry for QCD(AS/S) and Z{sub 2} interchange symmetry of the QCD(BF) are not broken in the phase continuously connected to R{sup 4} limit. When the S{sup 1} circle is endowed with periodic boundary conditions, the (nonthermal) phase diagrams of orbifold and orientifold QCD are still the same, however, both theories possess chirally symmetric phases which are absent in N=1 SYM. The match and mismatch of the phase diagrams depending on the spin structure of fermions along the S{sup 1} circle is naturally explained in terms of the necessary and sufficient symmetry realization conditions which determine the validity of the nonperturbative orbifold orientifold equivalence.
Moubayidin, Laila; Østergaard, Lars
2015-09-01
985 I. 985 II. 986 III. 987 IV. 988 V. 989 989 References 989 SUMMARY: The development of multicellular organisms depends on correct establishment of symmetry both at the whole-body scale and within individual tissues and organs. Setting up planes of symmetry must rely on communication between cells that are located at a distance from each other within the organism, presumably via mobile morphogenic signals. Although symmetry in nature has fascinated scientists for centuries, it is only now that molecular data to unravel mechanisms of symmetry establishment are beginning to emerge. As an example we describe the genetic and hormonal interactions leading to an unusual bilateral-to-radial symmetry transition of an organ in order to promote reproduction.
[Dehydration due to "mouth broken"].
Meijler, D P M; van Mossevelde, P W J; van Beek, R H T
2012-09-01
Two children were admitted to a medical centre due to dehydration after an oral injury and the extraction of a tooth. One child complained of "mouth broken". Dehydration is the most common water-electrolyte imbalance in children. Babies and young children are prone to dehydration due to their relatively large body surface area, the high percentage extracellular fluid, and the limited ability of the kidneys to conserve water. After the removal ofa tooth, after an oral trauma or in case of oral discomfort, a child is at greater risk of dehydration by reduced fluid and food intake due to oral pain and/or discomfort and anxiety to drink. In those cases, extra attention needs to be devoted to the intake of fluids.
Spontaneous breaking of the BRST symmetry in the ABJM theory
NASA Astrophysics Data System (ADS)
Faizal, Mir; Upadhyay, Sudhaker
2014-09-01
In this paper, we will analyze the ghost condensation in the ABJM theory. We will perform our analysis in N=1 superspace. We show that in the Delbourgo-Jarvis-Baulieu-Thierry-Mieg gauge the spontaneous breaking of BRST symmetry can occur in the ABJM theory. This spontaneous breaking of BRST symmetry is caused by ghost-anti-ghost condensation. We will also show that in the ABJM theory, the ghost-anti-ghost condensates remain present in the modified abelian gauge. Thus, the spontaneous breaking of BRST symmetry in ABJM theory can even occur in the modified abelian gauge.
Generalization of Friedberg-Lee symmetry
NASA Astrophysics Data System (ADS)
Huang, Chao-Shang; Li, Tianjun; Liao, Wei; Zhu, Shou-Hua
2008-07-01
We study the possible origin of Friedberg-Lee symmetry. First, we propose the generalized Friedberg-Lee symmetry in the potential by including the scalar fields in the field transformations, which can be broken down to the Friedberg-Lee symmetry spontaneously. We show that the generalized Friedberg-Lee symmetry allows a typical form of Yukawa couplings, and the realistic neutrino masses and mixings can be generated via the seesaw mechanism. If the right-handed neutrinos transform nontrivially under the generalized Friedberg-Lee symmetry, we can have the testable TeV scale seesaw mechanism. Second, we present two models with the SO(3)×U(1) global flavor symmetry in the lepton sector. After the flavor symmetry breaking, we can obtain the charged lepton masses, and explain the neutrino masses and mixings via the seesaw mechanism. Interestingly, the complete neutrino mass matrices are similar to those of the above models with generalized Friedberg-Lee symmetry. So the Friedberg-Lee symmetry is the residual symmetry in the neutrino mass matrix after the SO(3)×U(1) flavor symmetry breaking.
Spontaneous breaking of nilpotent symmetry in boundary BLG theory
NASA Astrophysics Data System (ADS)
Upadhyay, Sudhaker
2015-09-01
We exploit boundary term to preserve the supersymmetric gauge invariance of Bagger-Lambert-Gustavsson (BLG) theory. The fermionic rigid BRST and anti-BRST symmetries are studied in linear and nonlinear gauges. Remarkably, for Delbourgo-Jarvis-Baulieu-Thierry-Mieg (DJBTM) type gauge the spontaneous breaking of BRST symmetry occurs in the BLG theory. The responsible guy for such spontaneous breaking is ghost-antighost condensation. Further, we discuss the ghost-antighost condensates in the modified maximally Abelian (MMA) gauge in the BLG theory.
Quantum Field Theory Tools:. a Mechanism of Mass Generation of Gauge Fields
NASA Astrophysics Data System (ADS)
Flores-Baez, F. V.; Godina-Nava, J. J.; Ordaz-Hernandez, G.
We present a simple mechanism for mass generation of gauge fields for the Yang-Mills theory, where two gauge SU(N)-connections are introduced to incorporate the mass term. Variations of these two sets of gauge fields compensate each other under local gauge transformations with the local gauge transformations of the matter fields, preserving gauge invariance. In this way the mass term of gauge fields is introduced without violating the local gauge symmetry of the Lagrangian. Because the Lagrangian has strict local gauge symmetry, the model is a renormalizable quantum model. This model, in the appropriate limit, comes from a class of universal Lagrangians which define a new massive Yang-Mills theories without Higgs bosons.
Possible violations of spacetime symmetries
NASA Astrophysics Data System (ADS)
Urrutia, Luis
2016-10-01
The identification of symmetries has played a fundamental role in our understanding of physical phenomena. Nevertheless, in most cases such symmetries constitute only a zeroth-order approximation and they need to be broken so that the predictions of the theory are consistent with experimental observation. In particular, the almost sacred CPT and Lorentz symmetries, which are certainly part of the fundamental ideas of modern physics, need to be probed experimentally. Recently, such efforts have been intensified because different theoretical approaches aiming to understand the microstructure of space-time suggest the possibility that such symmetries could present minute violations. Up to now, and with increasing experimental sensitivities, no signs of violation have been found. Nevertheless, we observe that even the persistence of such negative results will have a profound impact. On one hand, they will provide those symmetries with a firm experimental basis. On the other, they will set stringent experimental bounds to be compared with the possible emergence of such violations in quantum gravity models based upon a discrete structure of space. We present a very general perspective of the research on Lorentz symmetry breaking, together with a review of a few specific topics.
On lattice chiral gauge theories
NASA Technical Reports Server (NTRS)
Maiani, L.; Rossi, G. C.; Testa, M.
1991-01-01
The Smit-Swift-Aoki formulation of a lattice chiral gauge theory is presented. In this formulation the Wilson and other non invariant terms in the action are made gauge invariant by the coupling with a nonlinear auxilary scalar field, omega. It is shown that omega decouples from the physical states only if appropriate parameters are tuned so as to satisfy a set of BRST identities. In addition, explicit ghost fields are necessary to ensure decoupling. These theories can give rise to the correct continuum limit. Similar considerations apply to schemes with mirror fermions. Simpler cases with a global chiral symmetry are discussed and it is shown that the theory becomes free at decoupling. Recent numerical simulations agree with those considerations.
SU{sub {ital q}}(2) lattice gauge theory
Bimonte, G.; Stern, A.; Vitale, P.
1996-07-01
We reformulate the Hamiltonian approach to lattice gauge theories such that, at the classical level, the gauge group does not act canonically, but instead as a Poisson-Lie group. At the quantum level, the symmetry gets promoted to a quantum group gauge symmetry. The theory depends on two parameters: the deformation parameter {lambda} and the lattice spacing {ital a}. We show that the system of Kogut and Susskind is recovered when {lambda}{r_arrow}0, while QCD is recovered in the continuum limit (for any {lambda}). We, thus, have the possibility of having a two-parameter regularization of QCD. {copyright} {ital 1996 The American Physical Society.}
Sufficient symmetry conditions for Topological Quantum Order.
Nussinov, Zohar; Ortiz, Gerardo
2009-10-06
We prove sufficient conditions for Topological Quantum Order at zero and finite temperatures. The crux of the proof hinges on the existence of low-dimensional Gauge-Like Symmetries, thus providing a unifying framework based on a symmetry principle. These symmetries may be actual invariances of the system, or may emerge in the low-energy sector. Prominent examples of Topological Quantum Order display Gauge-Like Symmetries. New systems exhibiting such symmetries include Hamiltonians depicting orbital-dependent spin exchange and Jahn-Teller effects in transition metal orbital compounds, short-range frustrated Klein spin models, and p+ip superconducting arrays. We analyze the physical consequences of Gauge-Like Symmetries (including topological terms and charges) and show the insufficiency of the energy spectrum, topological entanglement entropy, maximal string correlators, and fractionalization in establishing Topological Quantum Order. General symmetry considerations illustrate that not withstanding spectral gaps, thermal fluctuations may impose restrictions on suggested quantum computing schemes. Our results allow us to go beyond standard topological field theories and engineer systems with Topological Quantum Order.
Constraints on gauge-Higgs unification models at the LHC
NASA Astrophysics Data System (ADS)
Kitazawa, Noriaki; Sakai, Yuki
2016-02-01
We examine the possibility of observing the Kaluza-Klein (KK) gluons in gauge-Higgs unification models at the LHC with the energy s=14 TeV. We consider a benchmark model with the gauge symmetry SU(3)C×SU(3)W in five-dimensional spacetime, where SU(3)C is the gauge symmetry of the strong interaction and SU(3)W is that for the electroweak interaction and a Higgs doublet field. It is natural in general to introduce SU(3)C gauge symmetry in five-dimensional spacetime as well as SU(3)W gauge symmetry in gauge-Higgs unification (GHU) models. Since the fifth dimension is compactified to S1/Z 2 orbifold, there are KK modes of gluons in low-energy effective theory in four-dimensional spacetime. We investigate the resonance contribution of the first KK gluon to dijet invariant mass distribution at the LHC, and provide signal-to-noise ratios in various cases of KK gluon masses and kinematical cuts. Although the results are given in a specific benchmark model, we discuss their application to general GHU models with KK gluons. GHU models can be verified or constrained through the physics of the strong interaction, though they are proposed to solve the naturalness problem in electroweak symmetry breaking.
Nonlinear realization and hidden local symmetries
NASA Astrophysics Data System (ADS)
Bando, Masako; Kugo, Taichiro; Yamawaki, Koichi
1988-07-01
The idea of dynamical gauge bosons of hidden local symmetries in nonlinear sigma models is reviewed. Starting with a fresh look at the Goldstone theorem and low energy theorems, we present a modern review of the general theory of nonlinear realization both in nonsupersymmetric and supersymmetric cases. We then show that any nonlinear sigma model based on the manifold G/ H is gauge equivalent to a “linear” model possessing a Gglobal × Hlocal symmetry, Hlocal being a hidden local symmetry. The corresponding supersymmetric formulation is also presented. The above gauge equivalence can be extended to a model having a larger symmetry Gglobal × Glocal. Also reviewed are dynamical calculatio ns showing that in some two-, three- and four-dimensional models, the gauge bosons of the hidden local symmetries acquire the kinetic terms via quantum effects, thus becoming “dynamical”. We suggest that such a dynamical gauge boson may be a rather common phenomenon realized in Nature. As a realistic example, we examine the QCD case where we identify the vector mesons (ϱ,ω,ф,K ∗) with the dynamical gauge bosons of the hidden U(3) v local symmetry in the U(3) L × U(3) R/U(3) V nonlinear sigma model. The totality of the vector meson phenomenology seems to support our basic idea. The axial-vector mesons are also incorporated into our framework. Also given is a brief sketch of some applications of this formalism to unified models beyond the standard model, such as technicolor, composite W/Z boson and supergravity models.
49 CFR 230.39 - Broken staybolts.
Code of Federal Regulations, 2010 CFR
2010-10-01
..., DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Staybolts § 230.39 Broken staybolts. (a) Maximum allowable number of broken staybolts. No boiler shall be... inside the firebox or combustion chamber on a straight line. No boiler shall be allowed to remain...
Dual technicolor with hidden local symmetry
Belitsky, A. V.
2010-08-15
We consider a dual description of the technicolor-like gauge theory within the D4/D8-brane configuration with varying confinement and electroweak symmetry breaking scales. Constructing an effective truncated model valid below a certain cutoff, we identify the particle spectrum with Kaluza-Klein modes of the model in a manner consistent with the hidden local symmetry. Integrating out heavy states, we find that the low-energy action receives nontrivial corrections stemming from the mixing between standard model and heavy gauge bosons, which results in reduction of oblique parameters.
Gauge invariance and radiative corrections in an extra dimensional theory
NASA Astrophysics Data System (ADS)
Novales-Sánchez, H.; Toscano, J. J.
2011-04-01
The gauge structure of the four dimensional effective theory originated in a pure five dimensional Yang-Mills theory compactified on the orbifold S1 /Z2, is discussed on the basis of the BRST symmetry. If gauge parameters propagate in the bulk, the excited Kaluza-Klein (KK) modes are gauge fields and the four dimensional theory is gauge invariant only if the compactification is carried out by using curvatures as fundamental objects. The four dimensional theory is governed by two types of gauge transformations, one determined by the KK zero modes of the gauge parameters and the other by the excited ones. Within this context, a gauge-fixing procedure to quantize the KK modes that is covariant under the first type of gauge transformations is shown and the ghost sector induced by the gauge-fixing functions is presented. If the gauge parameters are confined to the usual four dimensional space-time, the known result in the literature is reproduced with some minor variants, although it is emphasized that the excited KK modes are not gauge fields, but matter fields transforming under the adjoint representation of SU4(N). A calculation of the one-loop contributions of the excited KK modes of the SUL(2) gauge group on the off-shell W+W-V, with V a photon or a Z boson, is exhibited. Such contributions are free of ultraviolet divergences and well-behaved at high energies.
NASA Astrophysics Data System (ADS)
Cheng, Meng; Zaletel, Michael; Barkeshli, Maissam; Vishwanath, Ashvin; Bonderson, Parsa
2016-10-01
The Lieb-Schultz-Mattis theorem and its higher-dimensional generalizations by Oshikawa and Hastings require that translationally invariant 2D spin systems with a half-integer spin per unit cell must either have a continuum of low energy excitations, spontaneously break some symmetries, or exhibit topological order with anyonic excitations. We establish a connection between these constraints and a remarkably similar set of constraints at the surface of a 3D interacting topological insulator. This, combined with recent work on symmetry-enriched topological phases with on-site unitary symmetries, enables us to develop a framework for understanding the structure of symmetry-enriched topological phases with both translational and on-site unitary symmetries, including the effective theory of symmetry defects. This framework places stringent constraints on the possible types of symmetry fractionalization that can occur in 2D systems whose unit cell contains fractional spin, fractional charge, or a projective representation of the symmetry group. As a concrete application, we determine when a topological phase must possess a "spinon" excitation, even in cases when spin rotational invariance is broken down to a discrete subgroup by the crystal structure. We also describe the phenomena of "anyonic spin-orbit coupling," which may arise from the interplay of translational and on-site symmetries. These include the possibility of on-site symmetry defect branch lines carrying topological charge per unit length and lattice dislocations inducing degeneracies protected by on-site symmetry.
Diffractive Scattering and Gauge/String Duality
Tan, Chung-I [Brown University, Providence, Rhode Island, United States
2016-07-12
High-energy diffractive scattering will be discussed based on Gauge/String duality. As shown by Brower, Polchinski, Strassler and Tan, the ubiquitous Pomeron emerges naturally in gauge theories with string-theoretical descriptions. Its existence is intimately tied to gluons, and also to the energy-momentum tensor. With a confining dual background metric, the Pomeron can be interpreted as a 'massive graviton'. In a single unified step, both its infrared and ultraviolet properties are dealt with, reflecting confinement and conformal symmetry respectively. An effective field theory for high-energy scattering can be constructed. Applications based on this approach will also be described.
Gauge fixing in higher-derivative gravity
NASA Astrophysics Data System (ADS)
Bartoli, A.; Julve, J.; Sánchez, E. J.
1999-07-01
Linearized 4-derivative gravity with a general gauge-fixing term is considered. By a Legendre transform and a suitable diagonalization procedure it is cast into a second-order equivalent form where the nature of the physical degrees of freedom, the gauge ghosts, the Weyl ghosts and the intriguing `third ghosts', characteristic to higher-derivative theories, is made explicit. The symmetries of the theory and the structure of the compensating Faddeev-Popov ghost sector exhibit non-trivial peculiarities. The unitarity breaking negative-norm Weyl ghosts, already present in the diff-invariant theory, are out of the reach of the ghost cancellation BRST mechanism.
Gauge invariant actions for string models
Banks, T.
1986-06-01
String models of unified interactions are elegant sets of Feynman rules for the scattering of gravitons, gauge bosons, and a host of massive excitations. The purpose of these lectures is to describe the progress towards a nonperturbative formulation of the theory. Such a formulation should make the geometrical meaning of string theory manifest and explain the many ''miracles'' exhibited by the string Feynman rules. There are some new results on gauge invariant observables, on the cosmological constant, and on the symmetries of interacting string field theory. 49 refs.
Entanglement in weakly coupled lattice gauge theories
NASA Astrophysics Data System (ADS)
Radičević, Ðorđe
2016-04-01
We present a direct lattice gauge theory computation that, without using dualities, demonstrates that the entanglement entropy of Yang-Mills theories with arbitrary gauge group G contains a generic logarithmic term at sufficiently weak coupling e. In two spatial dimensions, for a region of linear size r, this term equals 1/2 dim( G) log( e 2 r) and it dominates the universal part of the entanglement entropy. Such logarithmic terms arise from the entanglement of the softest mode in the entangling region with the environment. For Maxwell theory in two spatial dimensions, our results agree with those obtained by dualizing to a compact scalar with spontaneous symmetry breaking.
Massless gauge bosons other than the photon
Dobrescu, Bogdan A.; /Fermilab
2004-11-01
Gauge bosons associated with unbroken gauge symmetries, under which all standard model fields are singlets, may interact with ordinary matter via higher-dimensional operators. A complete set of dimension-six operators involving a massless U(1) field, {gamma}', and standard model fields is presented. The {mu} {yields} e{gamma}' decay, primordial nucleosynthesis, star cooling and other phenomena set lower limits on the scale of chirality-flip operators in the 1-15 TeV range, if the operators have coefficients given by the corresponding Yukawa couplings. Simple renormalizable models induce {gamma}' interactions with leptons or quarks at two loops, and may provide a cold dark matter candidate.
Strain gauge installation tool
Conard, Lisa Marie
1998-01-01
A tool and a method for attaching a strain gauge to a test specimen by maaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.
Symmetry breaking around a wormhole
NASA Astrophysics Data System (ADS)
Choudhury, A. L.
1996-11-01
We have modified the extended version Coule and Maeda's version (D. H. Coule and Kei-ichi Maeda, Class.Quant.Grav.7,995(1990)) of the Gidding-Strominger model (S. B. Giddings and A. Strominger, Nucl.Phys. B307, 854(l988)) of the euclidean gravitational field interacting with axion. The new model has R-symmetry in contrast to the previous model. At the lowest perturbation case the model retains a wormhole solution. We assume that the scalar expands adiabatically and satisfies ideal gas law in a crude first approximation. Under the Higg's mechanism the symmetry can be broken at the tree approximation. This mechanism, we hope, can be used to introduce the degeneracy of quark masses.
ERIC Educational Resources Information Center
Attanucci, Frank J.; Losse, John
2008-01-01
In a first calculus course, it is not unusual for students to encounter the theorems which state: If f is an even (odd) differentiable function, then its derivative is odd (even). In our paper, we prove some theorems which show how the symmetry of a continuous function f with respect to (i) the vertical line: x = a or (ii) with respect to the…
Gauge engineering and propagators
NASA Astrophysics Data System (ADS)
Maas, Axel
2017-03-01
Beyond perturbation theory gauge-fixing becomes more involved due to the Gribov-Singer ambiguity: The appearance of additional gauge copies requires to define a procedure how to handle them. For the case of Landau gauge the structure and properties of these additional gauge copies will be investigated. Based on these properties gauge conditions are constructed to account for these gauge copies. The dependence of the propagators on the choice of these complete gauge-fixings will then be investigated using lattice gauge theory for Yang-Mills theory. It is found that the implications for the infrared, and to some extent mid-momentum behavior, can be substantial. In going beyond the Yang-Mills case it turns out that the influence of matter can generally not be neglected. This will be briefly discussed for various types of matter.
Kim, Hyung Do
2006-11-28
We consider gauge messenger models in which X and Y gauge bosons and gauginos are messengers of supersymmetry breaking. In simple gauge messenger models, all the soft parameters except {mu} and B{mu} are calculated in terms of a single scale parameter MSUSY which is proportional to F / MGUT. Unique prediction on dark matter in gauge messenger models is discussed. (Based on hep-ph/0601036 and hep-ph/0607169)
A Study of Confinement and Dynamical Chiral Symmetry Breaking in QED3
Sanchez, Saul; Raya, Alfredo; Bashir, Adnan
2009-04-20
We study the gauge invariance of physical observables related to confinement and dynamical chiral symmetry breaking in unquenched QED3 for a simple truncation of the corresponding Schwinger-Dyson equations in arbitrary covariant gauges. An explicit implementation of Landau-Khalatnikov-Fradkin transformations renders these observables gauge independent.
Gauged flavor, supersymmetry and grand unification
NASA Astrophysics Data System (ADS)
Mohapatra, Rabindra N.
2012-07-01
I review a recent work on gauged flavor with left-right symmetry, where all masses and all Yukawa couplings owe their origin to spontaneous flavor symmetry breaking. This is suggested as a precursor to a full understanding of flavor of quarks and leptons. An essential ingredient of this approach is the existence of heavy vector-like fermions, which is the home of flavor, which subsequently gets transmitted to the familiar quarks and leptons via the seesaw mechanism. I then discuss implications of extending this idea to include supersymmetry and finally speculate on a possible grand unified model based on the gauge group SU(5)L×SU(5)R which provides a group theoretic origin for the vector-like fermions.
Symmetry and the thermodynamics of currents in open quantum systems
NASA Astrophysics Data System (ADS)
Manzano, Daniel; Hurtado, Pablo I.
2014-09-01
Symmetry is a powerful concept in physics, and its recent application to understand nonequilibrium behavior is providing deep insights and groundbreaking exact results. Here we show how to harness symmetry to control transport and statistics in open quantum systems. Such control is enabled by a first-order-type dynamic phase transition in current statistics and the associated coexistence of different transport channels (or nonequilibrium steady states) classified by symmetry. Microreversibility then ensues, via the Gallavotti-Cohen fluctuation theorem, a twin dynamic phase transition for rare current fluctuations. Interestingly, the symmetry present in the initial state is spontaneously broken at the fluctuating level, where the quantum system selects the symmetry sector that maximally facilitates a given fluctuation. We illustrate these results in a qubit network model motivated by the problem of coherent energy harvesting in photosynthetic complexes, and introduce the concept of a symmetry-controlled quantum thermal switch, suggesting symmetry-based design strategies for quantum devices with controllable transport properties.
Applications of chiral symmetry
Pisarski, R.D.
1995-03-01
The author discusses several topics in the applications of chiral symmetry at nonzero temperature. First, where does the rho go? The answer: up. The restoration of chiral symmetry at a temperature T{sub {chi}} implies that the {rho} and a{sub 1} vector mesons are degenerate in mass. In a gauged linear sigma model the {rho} mass increases with temperature, m{sub {rho}}(T{sub {chi}}) > m{sub {rho}}(0). The author conjectures that at T{sub {chi}} the thermal {rho} - a{sub 1}, peak is relatively high, at about {approximately}1 GeV, with a width approximately that at zero temperature (up to standard kinematic factors). The {omega} meson also increases in mass, nearly degenerate with the {rho}, but its width grows dramatically with temperature, increasing to at least {approximately}100 MeV by T{sub {chi}}. The author also stresses how utterly remarkable the principle of vector meson dominance is, when viewed from the modern perspective of the renormalization group. Secondly, he discusses the possible appearance of disoriented chiral condensates from {open_quotes}quenched{close_quotes} heavy ion collisions. It appears difficult to obtain large domains of disoriented chiral condensates in the standard two flavor model. This leads to the last topic, which is the phase diagram for QCD with three flavors, and its proximity to the chiral critical point. QCD may be very near this chiral critical point, and one might thereby generated large domains of disoriented chiral condensates.
Geometric phase and gauge connection in polyatomic molecules.
Wittig, Curt
2012-05-14
Geometric phase is an interesting topic that is germane to numerous and varied research areas: molecules, optics, quantum computing, quantum Hall effect, graphene, and so on. It exists only when the system of interest interacts with something it perceives as exterior. An isolated system cannot display geometric phase. This article addresses geometric phase in polyatomic molecules from a gauge field theory perspective. Gauge field theory was introduced in electrodynamics by Fock and examined assiduously by Weyl. It yields the gauge field A(μ), particle-field couplings, and the Aharonov-Bohm phase, while Yang-Mills theory, the cornerstone of the standard model of physics, is a template for non-Abelian gauge symmetries. Electronic structure theory, including nonadiabaticity, is a non-Abelian gauge field theory with matrix-valued covariant derivative. Because the wave function of an isolated molecule must be single-valued, its global U(1) symmetry cannot be gauged, i.e., products of nuclear and electron functions such as χ(n)ψ(n) are forbidden from undergoing local phase transformation on R, where R denotes nuclear degrees of freedom. On the other hand, the synchronous transformations (first noted by Mead and Truhlar): ψ(n)→ψ(n)e(iζ) and simultaneously χ(n)→χ(n)e(-iζ), preserve single-valuedness and enable wave functions in each subspace to undergo phase transformation on R. Thus, each subspace is compatible with a U(1) gauge field theory. The central mathematical object is Berry's adiabatic connection i
Quenched domain wall QCD with DBW2 gauge action toward nucleon decay matrix element calculation
NASA Astrophysics Data System (ADS)
Aoki, Yasumichi
2001-10-01
The domain wall fermion action is a promising way to control chiral symmetry in lattice gauge theory. By the good chiral symmetry of this approach even at finite lattice spacing, one is able to extract hadronic matrix elements, like kaon weak matrix elements, for which the symmetry is extremely important. Ordinary fermions with poor chiral symmetry make calculation difficult because of the large mixing of operators with different chiral structure. Even though the domain wall fermion action with the simple Wilson gauge action has a good chiral symmetry, one can further improve the symmetry by using a different gauge action. We take a non-perturbatively improved action, the DBW2 action of the QCD Taro group. Hadron masses are systematically examined for a range of parameters. Application to nucleon decay matrix element is also discussed.
Light-cone gauge for 1 + 1 strings
NASA Astrophysics Data System (ADS)
Smith, Eric
1992-09-01
Explicit construction of the light-cone gauge quantum theory of bosonic strings in 1 + 1 space-time dimensions reveals unexpected structures. One is the existence of a gauge choice that gives a free action at the price of propagating ghosts and a nontrivial BRST charge. Fixing this gauge leaves a U(1) Kac-Moody algebra of residual symmetry, generated by a conformal tensor of rank two and a conformal scalar. Another is that the BRST charge made from these currents is nilpotent when the action includes a linear dilaton background, independent of the particular value of the dilaton gradient. Space-time Lorentz invariance in this theory is still elusive, however, because of the linear dilaton background and the nature of the gauge symmetries.
Symmetries and their breakings at microscopic and cosmic scales
NASA Astrophysics Data System (ADS)
Huo, Ran
We organize several research projects in the author's Ph.D. career which are distinct in nature into this thesis, in the view of symmetry fulfillments and breakings. Some broken gauge symmetry may give a massive neutral gauge boson Z', and this Z' may be the mediator between the SM and the dark matter sector, forming the dark portal. We consider the scenario of a leptophobic light Z' vector boson as the mediator, and study the prospect of searching for it at the 8 TeV Large Hadron Collider (LHC). To improve the reach in the low mass region, we perform a detailed study of the processes that the Z' is produced in association with jet, photon, W+/- and Z 0. We show that in the region where the mass of Z' is between 80 and 400 GeV, the constraint from associated production can be comparable or even stronger than the known monojet and dijet constraints. We study an extension of the Minimal Supersymmetric Standard Model with a gauge group SU(2)1 ⊗ SU(2) 2 breaking to SU(2)L. The extra wino has an enhanced gauge coupling to the SM-like Higgs boson and, if light, has a relevant impact on the weak scale phenomenology. Compared with the MSSM case, the low energy Higgs quartic coupling is modified both by extra D-term corrections and by a modification of its renormalization group evolution from high energies. At low values of tan beta, the latter effect may be dominant. This leads to interesting regions of parameter space in which the model can accommodate a 125 GeV Higgs with relatively light third generation squarks and an increased h → gammagamma decay branching ratio, while still satisfying the constraints from electroweak precision data and Higgs vacuum stability. We also study some toy model towards electroweak baryogenesis, which in the wino-higgsino case can be fulfilled as the above gauge extension of the MSSM model. The fermionic component have a mixing through vector like mass terms, through which the Higgs diphoton decay branching ratio can be tuned, and
Cosmological properties of a gauged axion
Coriano, Claudio; Mariano, Antonio; Guzzi, Marco; Lazarides, George
2010-09-15
We analyze the most salient cosmological features of axions in extensions of the standard model with a gauged anomalous extra U(1) symmetry. The model is built by imposing the constraint of gauge invariance in the anomalous effective action, which is extended with Wess-Zumino counterterms. These generate axionlike interactions of the axions to the gauge fields and a gauged shift symmetry. The scalar sector is assumed to acquire a nonperturbative potential after inflation, at the electroweak phase transition, which induces a mixing of the Stueckelberg field of the model with the scalars of the electroweak sector, and at the QCD phase transition. We discuss the possible mechanisms of sequential misalignments which could affect the axions of these models, and generated, in this case, at both transitions. We compute the contribution of these particles to dark matter, quantifying their relic densities as a function of the Stueckelberg mass. We also show that models with a single anomalous U(1) in general do not account for the dark energy, due to the presence of mixed U(1)-SU(3) anomalies.
General relativity as the effective theory of GL(4,R) spontaneous symmetry breaking
NASA Astrophysics Data System (ADS)
Tomboulis, E. T.
2011-10-01
We assume a GL(4,R) space-time symmetry which is spontaneously broken to SO(3,1). We carry out the coset construction of the effective theory for the nonlinearly realized broken symmetry in terms of the Goldstone fields and matter fields transforming linearly under the unbroken Lorentz subgroup. We then identify functions of the Goldstone and matter fields that transform linearly also under the broken symmetry. Expressed in terms of these quantities the effective theory reproduces the vierbein formalism of general relativity with general coordinate invariance being automatically realized nonlinearly over GL(4,R). The coset construction makes no assumptions about any underlying theory that might be responsible for the assumed symmetry breaking. We give a brief discussion of the possibility of field theories with GL(4,R) rather than Lorentz space-time symmetry providing the underlying dynamics.
Imaging chiral symmetry breaking from Kekulé bond order in graphene
NASA Astrophysics Data System (ADS)
Gutiérrez, Christopher; Kim, Cheol-Joo; Brown, Lola; Schiros, Theanne; Nordlund, Dennis; Lochocki, Edward B.; Shen, Kyle M.; Park, Jiwoong; Pasupathy, Abhay N.
2016-10-01
Chirality--or `handedness’--is a symmetry property crucial to fields as diverse as biology, chemistry and high-energy physics. In graphene, chiral symmetry emerges naturally as a consequence of the carbon honeycomb lattice. This symmetry can be broken by interactions that couple electrons with opposite momenta in graphene. Here we directly visualize the formation of Kekulé bond order, one such phase of broken chiral symmetry, in an ultraflat graphene sheet grown epitaxially on a copper substrate. We show that its origin lies in the interactions between individual vacancies in the copper substrate that are mediated electronically by the graphene. We show that this interaction causes the bonds in graphene to distort, creating a phase with broken chiral symmetry. The Kekulé ordering is robust at ambient temperature and atmospheric conditions, indicating that intercalated atoms may be harnessed to drive graphene and other two-dimensional materials towards electronically desirable and exotic collective phases.
General relativity as the effective theory of GL(4,R) spontaneous symmetry breaking
Tomboulis, E. T.
2011-10-15
We assume a GL(4,R) space-time symmetry which is spontaneously broken to SO(3,1). We carry out the coset construction of the effective theory for the nonlinearly realized broken symmetry in terms of the Goldstone fields and matter fields transforming linearly under the unbroken Lorentz subgroup. We then identify functions of the Goldstone and matter fields that transform linearly also under the broken symmetry. Expressed in terms of these quantities the effective theory reproduces the vierbein formalism of general relativity with general coordinate invariance being automatically realized nonlinearly over GL(4,R). The coset construction makes no assumptions about any underlying theory that might be responsible for the assumed symmetry breaking. We give a brief discussion of the possibility of field theories with GL(4,R) rather than Lorentz space-time symmetry providing the underlying dynamics.
Doff, A.
2007-08-01
The coupling constants g{sub L} and g{sub X} of some versions of the SU(3){sub L} x U(1){sub X} extension of the standard model are related through to relationship g{sub X}{sup 2}/g{sub L}{sup 2}=sin{sup 2}{theta}{sub W}/(1-4sin{sup 2}{theta}{sub W}). This fact suggest that the SU(3){sub L} x U(1){sub X} gauge symmetry in this class of models can be broken dynamically to the standard model at TeV scale without requiring the introduction of fundamental scalars. This possibility was investigated by Das and Jain who considered the only first version of this class of models. In this brief report we discuss an energy criterion to verify the most probable version of the SU(3){sub L} x U(1){sub X} model that is realized in nature.
Nilpotent symmetries in supergroup field cosmology
NASA Astrophysics Data System (ADS)
Upadhyay, Sudhaker
2015-04-01
In this paper, we study the gauge invariance of the third quantized supergroup field cosmology which is a model for multiverse. Further, we propose both the infinitesimal (usual) as well as the finite superfield-dependent BRST symmetry transformations which leave the effective theory invariant. The effects of finite superfield-dependent BRST transformations on the path integral (so-called void functional in the case of third quantization) are implemented. Within the finite superfield-dependent BRST formulation, the finite superfield-dependent BRST transformations with specific parameter switch the void functional from one gauge to another. We establish this result for the most general gauge with the help of explicit calculations which holds for all possible sets of gauge choices at both the classical and the quantum levels.
The experience of a broken heart.
Fernandes, Jill Renee Hecker
2005-12-01
Infants who have congenital heart disease (CHD) are born with a "broken heart." Health care professionals are presented with the challenge of caring for the infant's physiologically defective heart as well as the emotional heart of the parents as they begin to accept this diagnosis. This study allowed parents to share this experience through phenomenology as an inquiry approach. These descriptions will assist in providing a more complete and deeper understanding of the parent's experience of CHD. Thus, all will know "the experience of a broken heart."
History of electroweak symmetry breaking
NASA Astrophysics Data System (ADS)
Kibble, T. W. B.
2015-07-01
In this talk, I recall the history of the development of the unified electroweak theory, incorporating the symmetry-breaking Higgs mechanism, as I saw it from my standpoint as a member of Abdus Salam's group at Imperial College. I start by describing the state of physics in the years after the Second World War, explain how the goal of a unified gauge theory of weak and electromagnetic interactions emerged, the obstacles encountered, in particular the Goldstone theorem, and how they were overcome, followed by a brief account of more recent history, culminating in the historic discovery of the Higgs boson in 2012.
Strain gauge installation tool
Conard, L.M.
1998-06-16
A tool and a method are disclosed for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool. 6 figs.
A simple example of a classical gauge transformation
NASA Technical Reports Server (NTRS)
Whitten, R. C.
1983-01-01
Attention is given to the manner in which the interaction of a gravitational field with a diffusing gas is induced by a gauge transformation. Since the gas can be thought of as a field, the diffusion process may be represented by a Lagrangian density with the symmetry property of invariance under translation. While this property is lost when the field interacts with a static gravitational field, it is formally restored when an appropriate gauge transformation is performed. This ascription of field properties to a gas offers an illuminating illustration of the coupling of matter to a gauge field within the context of classical mechanics.
Composite gauge-bosons made of fermions
NASA Astrophysics Data System (ADS)
Suzuki, Mahiko
2016-07-01
We construct a class of Abelian and non-Abelian local gauge theories that consist only of matter fields of fermions. The Lagrangian is local and does not contain an auxiliary vector field nor a subsidiary condition on the matter fields. It does not involve an extra dimension nor supersymmetry. This Lagrangian can be extended to non-Abelian gauge symmetry only in the case of SU(2) doublet matter fields. We carry out an explicit diagrammatic computation in the leading 1 /N order to show that massless spin-one bound states appear with the correct gauge coupling. Our diagram calculation exposes the dynamical features that cannot be seen in the formal auxiliary vector-field method. For instance, it shows that the s -wave fermion-antifermion interaction in the 3S1 channel (ψ ¯ γμψ ) alone cannot form the bound gauge bosons; the fermion-antifermion pairs must couple to the d -wave state too. One feature common to our class of Lagrangian is that the Noether current does not exist. Therefore it evades possible conflict with the no-go theorem of Weinberg and Witten on the formation of the non-Abelian gauge bosons.
High temperature pressure gauge
Echtler, J. Paul; Scandrol, Roy O.
1981-01-01
A high temperature pressure gauge comprising a pressure gauge positioned in fluid communication with one end of a conduit which has a diaphragm mounted in its other end. The conduit is filled with a low melting metal alloy above the diaphragm for a portion of its length with a high temperature fluid being positioned in the remaining length of the conduit and in the pressure gauge.
The US patent system is broken.
Pieczenik, George
2013-08-01
In discussions in this issue of RBM Online relating to a patent granted to Auxogyn, Professor Renee Reijo Pera claims this is not about a "broken patent system". I shall demonstrate how dysfunctional the patent system has become and how much in denial 'inventor' Renee Reijo Pera is about her invention differing from a naturally occurring phenomenon.
Symmetry-enriched topological invariants from tensor network representations
NASA Astrophysics Data System (ADS)
Ware, Brayden; Cheng, Meng; Bauer, Bela
We examine topologically ordered quantum phases in 2+1 dimensions where in the presence of symmetries the topological phase splits into multiple symmetry enriched topological (SET) phases. These SET phases become adiabatically connected when the symmetry is broken, but are separated by phase transitions when symmetry is enforced. Using tensor network representations of representative wavefunctions for certain SET phases, we demonstrate the calculation of the extended modular matrices, a generalization of the well-known modular matrices that have been used to robustly characterize topological phases in numerical calculations. Here, the crucial extension is to systems with symmetry defects. The extended modular matrices are used to form symmetry-enriched topological invariants which distinguish different SET phases.
Modified Friedberg-Lee symmetry for neutrino mixing
NASA Astrophysics Data System (ADS)
Zhao, Zhen-hua
2015-12-01
In this paper, we put forward a special neutrino mass matrix which is invariant under a modified Friedberg-Lee (FL) transformation νe→νe-2 ξ and νμ ,τ→νμ ,τ+ξ with ξ being a space-time independent element of the Grassmann algebra. Compared to the original FL symmetry (with the transformation νe ,μ ,τ→νe ,μ ,τ+ξ ) which results in the TM2 neutrino mixing, the modified FL symmetry will lead us to the TM1 mixing which has a better agreement with the experimental results. While the original FL symmetry has to be broken in order to produce a realistic neutrino mass spectrum, the modified FL symmetry is allowed to remain intact and give us a vanishing m1. A combination of the FL symmetry with the μ -τ reflection symmetry is also discussed.
Hidden local symmetry and beyond
NASA Astrophysics Data System (ADS)
Yamawaki, Koichi
Gerry Brown was a godfather of our hidden local symmetry (HLS) for the vector meson from the birth of the theory throughout his life. The HLS is originated from very nature of the nonlinear realization of the symmetry G based on the manifold G/H, and thus is universal to any physics based on the nonlinear realization. Here, I focus on the Higgs Lagrangian of the Standard Model (SM), which is shown to be equivalent to the nonlinear sigma model based on G/H = SU(2)L ×SU(2)R/SU(2)V with additional symmetry, the nonlinearly-realized scale symmetry. Then, the SM does have a dynamical gauge boson of the SU(2)V HLS, “SM ρ meson”, in addition to the Higgs as a pseudo-dilaton as well as the NG bosons to be absorbed in to the W and Z. Based on the recent work done with Matsuzaki and Ohki, I discuss a novel possibility that the SM ρ meson acquires kinetic term by the SM dynamics itself, which then stabilizes the skyrmion dormant in the SM as a viable candidate for the dark matter, what we call “dark SM skyrmion (DSMS)”.
Geometry and symmetries in lattice spinor gravity
Wetterich, C.
2012-09-15
Lattice spinor gravity is a proposal for regularized quantum gravity based on fermionic degrees of freedom. In our lattice model the local Lorentz symmetry is generalized to complex transformation parameters. The difference between space and time is not put in a priori, and the euclidean and the Minkowski quantum field theory are unified in one functional integral. The metric and its signature arise as a result of the dynamics, corresponding to a given ground state or cosmological solution. Geometrical objects as the vierbein, spin connection or the metric are expectation values of collective fields built from an even number of fermions. The quantum effective action for the metric is invariant under general coordinate transformations in the continuum limit. The action of our model is found to be also invariant under gauge transformations. We observe a 'geometrical entanglement' of gauge- and Lorentz-transformations due to geometrical objects transforming non-trivially under both types of symmetry transformations. - Highlights: Black-Right-Pointing-Pointer We formulate the geometrical aspects of a proposal for a lattice regularized model of quantum gravity. Black-Right-Pointing-Pointer The vierbein shows an entanglement between Lorentz symmetry and gauge symmetry. Black-Right-Pointing-Pointer Euclidean and Minkowski signatures of the collective metric and the vierbein are described within the same functional integral.
Dark matter and global symmetries
NASA Astrophysics Data System (ADS)
Mambrini, Yann; Profumo, Stefano; Queiroz, Farinaldo S.
2016-09-01
General considerations in general relativity and quantum mechanics are known to potentially rule out continuous global symmetries in the context of any consistent theory of quantum gravity. Assuming the validity of such considerations, we derive stringent bounds from gamma-ray, X-ray, cosmic-ray, neutrino, and CMB data on models that invoke global symmetries to stabilize the dark matter particle. We compute up-to-date, robust model-independent limits on the dark matter lifetime for a variety of Planck-scale suppressed dimension-five effective operators. We then specialize our analysis and apply our bounds to specific models including the Two-Higgs-Doublet, Left-Right, Singlet Fermionic, Zee-Babu, 3-3-1 and Radiative See-Saw models. Assuming that (i) global symmetries are broken at the Planck scale, that (ii) the non-renormalizable operators mediating dark matter decay have O (1) couplings, that (iii) the dark matter is a singlet field, and that (iv) the dark matter density distribution is well described by a NFW profile, we are able to rule out fermionic, vector, and scalar dark matter candidates across a broad mass range (keV-TeV), including the WIMP regime.
Continuous symmetry measures for complex symmetry group.
Dryzun, Chaim
2014-04-05
Symmetry is a fundamental property of nature, used extensively in physics, chemistry, and biology. The Continuous symmetry measures (CSM) is a method for estimating the deviation of a given system from having a certain perfect symmetry, which enables us to formulate quantitative relation between symmetry and other physical properties. Analytical procedures for calculating the CSM of all simple cyclic point groups are available for several years. Here, we present a methodology for calculating the CSM of any complex point group, including the dihedral, tetrahedral, octahedral, and icosahedral symmetry groups. We present the method and analyze its performances and errors. We also introduce an analytical method for calculating the CSM of the linear symmetry groups. As an example, we apply these methods for examining the symmetry of water, the symmetry maps of AB4 complexes, and the symmetry of several Lennard-Jones clusters.
Strong Coupling Gauge Theories in LHC ERA
NASA Astrophysics Data System (ADS)
Fukaya, H.; Harada, M.; Tanabashi, M.; Yamawaki, K.
2011-01-01
AdS/QCD, light-front holography, and the nonperturbative running coupling / Stanley J. Brodsky, Guy de Teramond and Alexandre Deur -- New results on non-abelian vortices - Further insights into monopole, vortex and confinement / K. Konishi -- Study on exotic hadrons at B-factories / Toru Iijima -- Cold compressed baryonic matter with hidden local symmetry and holography / Mannque Rho -- Aspects of baryons in holographic QCD / T. Sakai -- Nuclear force from string theory / K. Hashimoto -- Integrating out holographic QCD back to hidden local symmetry / Masayasu Harada, Shinya Matsuzaki and Koichi Yamawaki -- Holographic heavy quarks and the giant Polyakov loop / Gianluca Grignani, Joanna Karczmarek and Gordon W. Semenoff -- Effect of vector-axial-vector mixing to dilepton spectrum in hot and/or dense matter / Masayasu Harada and Chihiro Sasaki -- Infrared behavior of ghost and gluon propagators compatible with color confinement in Yang-Mills theory with the Gribov horizon / Kei-Ichi Kondo -- Chiral symmetry breaking on the lattice / Hidenori Fukaya [for JLQCD and TWQCD collaborations] -- Gauge-Higgs unification: Stable Higgs bosons as cold dark matter / Yutaka Hosotani -- The limits of custodial symmetry / R. Sekhar Chivukula ... [et al.] -- Higgs searches at the tevatron / Kazuhiro Yamamoto [for the CDF and D[symbol] collaborations] -- The top triangle moose / R. S. Chivukula ... [et al.] -- Conformal phase transition in QCD like theories and beyond / V. A. Miransky -- Gauge-Higgs unification at LHC / Nobuhito Maru and Nobuchika Okada -- W[symbol]W[symbol] scattering in Higgsless models: Identifying better effective theories / Alexander S. Belyaev ... [et al.] -- Holographic estimate of Muon g - 2 / Deog Ki Hong -- Gauge-Higgs dark matter / T. Yamashita -- Topological and curvature effects in a multi-fermion interaction model / T. Inagaki and M. Hayashi -- A model of soft mass generation / J. Hosek -- TeV physics and conformality / Thomas Appelquist -- Conformal
Symmetry, conservation laws, and theoretical particle physics
NASA Astrophysics Data System (ADS)
Krumins, Andris Visvaldis
In this work, we trace the role of symmetry throughout the history of theoretical particle physics, paying particular attention to the role of group theory, the formal mathematics of symmetry. After an analysis of the role of conservation laws and invariance in the theory of general relativity, we move on to Weyl's gauge theory of 1918, which was developed within the context of general relativity as an attempt to unify gravitation and electromagnetism. Weyl was trying to exploit an invariance of scale, and although his theory was experimentally refuted, it provided a formulation of the conservation of charge. After the advent of quantum mechanics, gauge theory was reinterpreted by London as an invariance of the wave-function. Weyl and Wigner studied group theory in the context of quantum mechanics, but the broadness of its application had yet to be appreciated. Symmetry was soon exploited in the nuclear interactions, however, and we examine the events leading to the discovery of SU(2) of isotopic spin. We analyze how the discovery of strangeness was linked to the generalization of SU(2) to SU(3), and also how it led to a differentiation between the strong interactions, which conserve isotopic spin and strangeness, and the weak interactions, which violate these conservation laws, along with the conservation of parity. Yang and Mills were impressed with gauge invariance, and in 1954, they took the bold step of imposing it upon the Lagrangian of the strong interactions, forcing the introduction of three new gauge fields. There was a problem, however, because although the short-range of the strong interactions implied that these gauge bosons should be massive, they needed to be massless in order to preserve gauge invariance. In addition, efforts were made to extend Yang-Mills theory to the weak interactions, but they also faced the same zero-mass problem. This problem was finally solved in 1967, when Weinberg and Salam showed how gauge boson masses could be generated
Breaking the Symmetry in Molecular Nanorings
2016-01-01
Because of their unique electronic properties, cyclic molecular structures ranging from benzene to natural light-harvesting complexes have received much attention. Rigid π-conjugated templated porphyrin nanorings serve as excellent model systems here because they possess well-defined structures that can readily be controlled and because they support highly delocalized excitations. In this study, we have deliberately modified a series of six-porphyrin nanorings to examine the impact of lowering the rotational symmetry on their photophysical properties. We reveal that as symmetry distortions increase in severity along the series of structures, spectral changes and an enhancement of radiative emission strength occur, which derive from a transfer of oscillator strength into the lowest (k = 0) state. We find that concomitantly, the degeneracy of the dipole-allowed first excited (k = ±1) state is lifted, leading to an ultrafast polarization switching effect in the emission from strongly symmetry-broken nanorings. PMID:26735906
Bartholomew, M. J.
2016-01-01
To improve the quantitative description of precipitation processes in climate models, the Atmospheric Radiation Measurement (ARM) Climate Research Facility deployed rain gauges located near disdrometers (DISD and VDIS data streams). This handbook deals specifically with the rain gauges that make the observations for the RAIN data stream. Other precipitation observations are made by the surface meteorology instrument suite (i.e., MET data stream).
Equivalence of light-cone and conformal gauges in two-dimensional quantum gravity
Ahn, G.J.; Kim, W.T.; Park, Y.J.; Kim, K.Y. )
1992-08-20
In this paper, the authors show that the light-cone and conformal gauges are equivalent in the sense that the well known SL(2,R) current structure in the light-cone gauge is obtained from the results in the conformal one under a proper coordinate transformation. This result is due to the residual symmetry of the scalar field [Phi].
Nonlinear W∞ as asymptotic symmetry of three-dimensional higher spin AdS gravity
NASA Astrophysics Data System (ADS)
Henneaux, Marc; Rey, Soo-Jong
2010-12-01
We investigate the asymptotic symmetry algebra of (2+1)-dimensional higher spin, anti-de Sitter gravity. We use the formulation of the theory as a Chern-Simons gauge theory based on the higher spin algebra hs(1 , 1). Expanding the gauge connection around asymptotically anti-de Sitter spacetime, we specify consistent boundary conditions on the higher spin gauge fields. We then study residual gauge transformation, the corresponding surface terms and their Poisson bracket algebra. We find that the asymptotic symmetry algebra is a nonlinearly realized W ∞ algebra with classical central charges. We discuss implications of our results to quantum gravity and to various situations in string theory.
Local subsystems in gauge theory and gravity
NASA Astrophysics Data System (ADS)
Donnelly, William; Freidel, Laurent
2016-09-01
We consider the problem of defining localized subsystems in gauge theory and gravity. Such systems are associated to spacelike hypersurfaces with boundaries and provide the natural setting for studying entanglement entropy of localized subsystems. We present a general formalism to associate a gauge-invariant classical phase space to a spatial slice with boundary by introducing new degrees of freedom on the boundary. In Yang-Mills theory the new degrees of freedom are a choice of gauge on the boundary, transformations of which are generated by the normal component of the nonabelian electric field. In general relativity the new degrees of freedom are the location of a codimension-2 surface and a choice of conformal normal frame. These degrees of freedom transform under a group of surface symmetries, consisting of diffeomorphisms of the codimension-2 boundary, and position-dependent linear deformations of its normal plane. We find the observables which generate these symmetries, consisting of the conformal normal metric and curvature of the normal connection. We discuss the implications for the problem of defining entanglement entropy in quantum gravity. Our work suggests that the Bekenstein-Hawking entropy may arise from the different ways of gluing together two partial Cauchy surfaces at a cross-section of the horizon.
Dynamics of symmetry breaking during quantum real-time evolution in a minimal model system.
Heyl, Markus; Vojta, Matthias
2014-10-31
One necessary criterion for the thermalization of a nonequilibrium quantum many-particle system is ergodicity. It is, however, not sufficient in cases where the asymptotic long-time state lies in a symmetry-broken phase but the initial state of nonequilibrium time evolution is fully symmetric with respect to this symmetry. In equilibrium, one particular symmetry-broken state is chosen as a result of an infinitesimal symmetry-breaking perturbation. From a dynamical point of view the question is: Can such an infinitesimal perturbation be sufficient for the system to establish a nonvanishing order during quantum real-time evolution? We study this question analytically for a minimal model system that can be associated with symmetry breaking, the ferromagnetic Kondo model. We show that after a quantum quench from a completely symmetric state the system is able to break its symmetry dynamically and discuss how these features can be observed experimentally.
Broken Ergodicity in Ideal, Homogeneous, Incompressible Turbulence
NASA Technical Reports Server (NTRS)
Morin, Lee; Shebalin, John; Fu, Terry; Nguyen, Phu; Shum, Victor
2010-01-01
We discuss the statistical mechanics of numerical models of ideal homogeneous, incompressible turbulence and their relevance for dissipative fluids and magnetofluids. These numerical models are based on Fourier series and the relevant statistical theory predicts that Fourier coefficients of fluid velocity and magnetic fields (if present) are zero-mean random variables. However, numerical simulations clearly show that certain coefficients have a non-zero mean value that can be very large compared to the associated standard deviation. We explain this phenomena in terms of broken ergodicity', which is defined to occur when dynamical behavior does not match ensemble predictions on very long time-scales. We review the theoretical basis of broken ergodicity, apply it to 2-D and 3-D fluid and magnetohydrodynamic simulations of homogeneous turbulence, and show new results from simulations using GPU (graphical processing unit) computers.
Remarks on asymptotic symmetries and the subleading soft photon theorem
NASA Astrophysics Data System (ADS)
Conde, Eduardo; Mao, Pujian
2017-01-01
A deep connection has been recently established between soft theorems and symmetries at null infinity in gravity and gauge theories, recasting the former as Ward identities of the latter. In particular, different orders (in the frequency of the soft particle) in the soft theorems are believed to be controlled by different asymptotic symmetries. In this paper we argue that this need not be the case by focusing on the soft photon theorem. We argue that the subleading soft factor follows from the same symmetry responsible for the leading one, namely certain residual (large) gauge transformations of the gauge theory. In particular, expanding the associated charge in inverse powers of the radial coordinate, the (sub)leading charge yields the (sub)leading soft factor.
BRST symmetry for Regge-Teitelboim-based minisuperspace models
NASA Astrophysics Data System (ADS)
Upadhyay, Sudhaker; Paul, Biswajit
2016-07-01
The Einstein-Hilbert action in the context of higher derivative theories is considered for finding their BRST symmetries. Being a constraint system, the model is transformed in the minisuperspace language with the FRLW background and the gauge symmetries are explored. Exploiting the first order formalism developed by Banerjee et al. the diffeomorphism symmetry is extracted. From the general form of the gauge transformations of the field, the analogous BRST transformations are calculated. The effective Lagrangian is constructed by considering two gauge-fixing conditions. Further, the BRST (conserved) charge is computed, which plays an important role in defining the physical states from the total Hilbert space of states. The finite field-dependent BRST formulation is also studied in this context where the Jacobian for the functional measure is illustrated specifically.
750 GeV messenger of dark conformal symmetry breaking
NASA Astrophysics Data System (ADS)
Davoudiasl, Hooman; Zhang, Cen
2016-03-01
The tentative hints for a diphoton resonance at a mass of ˜750 GeV from the ATLAS and CMS experiments at the LHC may be interpreted as first contact with a "dark" sector with a spontaneously broken conformal symmetry. The implied TeV scale of the dark sector may be motivated by the interaction strength required to accommodate a viable thermal relic dark matter (DM) candidate. We model the conformal dynamics using a Randall-Sundrum-type five-dimensional geometry whose IR boundary is identified with the dynamics of the composite dark sector, while the Standard Model (SM) matter content resides on the UV boundary, corresponding to "elementary" fields. We allow the gauge fields to reside in the five-dimensional bulk, which can be minimally chosen to be S U (3 )c×U (1 )Y. The "dark" radion is identified as the putative 750 GeV resonance. Heavy vectorlike fermions, often invoked to explain the diphoton excess, are not explicitly present in our model and are not predicted to appear in the spectrum of TeV scale states. Our minimal setup favors scalar DM of O (TeV ) mass. A generic expectation in this scenario, suggested by DM considerations, is the appearance of vector bosons at ˜ few TeV, corresponding to the gluon and hypercharge Kaluza-Klein (KK) modes that couple to UV boundary states with strengths that are suppressed uniformly compared to their SM values. Our analysis suggests that these KK modes could be within the reach of the LHC in the coming years.
On discrete symmetries for a whole Abelian model
Chauca, J.; Doria, R.
2012-09-24
Considering the whole concept applied to gauge theory a nonlinear abelian model is derived. A next step is to understand on the model properties. At this work, it will be devoted to discrete symmetries. For this, we will work based in two fields reference systems. This whole gauge symmetry allows to be analyzed through different sets which are the constructor basis {l_brace}D{sub {mu}},X{sup i}{sub {mu}}{r_brace} and the physical basis {l_brace}G{sub {mu}I}{r_brace}. Taking as fields reference system the diagonalized spin-1 sector, P, C, T and PCT symmetries are analyzed. They show that under this systemic model there are conservation laws driven for the parts and for the whole. It develops the meaning of whole-parity, field-parity and so on. However it is the whole symmetry that rules. This means that usually forbidden particles as pseudovector photons can be introduced through such whole abelian system. As result, one notices that the fields whole {l_brace}G{sub {mu}I}{r_brace} manifest a quanta diversity. It involves particles with different spins, masses and discrete quantum numbers under a same gauge symmetry. It says that without violating PCT symmetry different possibilities on discrete symmetries can be accommodated.
Non-Abelian gauge field theory in scale relativity
Nottale, Laurent; Celerier, Marie-Noeelle; Lehner, Thierry
2006-03-15
Gauge field theory is developed in the framework of scale relativity. In this theory, space-time is described as a nondifferentiable continuum, which implies it is fractal, i.e., explicitly dependent on internal scale variables. Owing to the principle of relativity that has been extended to scales, these scale variables can themselves become functions of the space-time coordinates. Therefore, a coupling is expected between displacements in the fractal space-time and the transformations of these scale variables. In previous works, an Abelian gauge theory (electromagnetism) has been derived as a consequence of this coupling for global dilations and/or contractions. We consider here more general transformations of the scale variables by taking into account separate dilations for each of them, which yield non-Abelian gauge theories. We identify these transformations with the usual gauge transformations. The gauge fields naturally appear as a new geometric contribution to the total variation of the action involving these scale variables, while the gauge charges emerge as the generators of the scale transformation group. A generalized action is identified with the scale-relativistic invariant. The gauge charges are the conservative quantities, conjugates of the scale variables through the action, which find their origin in the symmetries of the ''scale-space.'' We thus found in a geometric way and recover the expression for the covariant derivative of gauge theory. Adding the requirement that under the scale transformations the fermion multiplets and the boson fields transform such that the derived Lagrangian remains invariant, we obtain gauge theories as a consequence of scale symmetries issued from a geometric space-time description.
Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MaCarthur, Charles D.; Cala, Gregory C.
1991-01-01
A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.
Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.
1991-01-01
A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator wherein each thermographic layer comprises a plurality of respective thermographic phosphors. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.
Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.
1991-01-01
A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.
Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.
1991-06-25
A heat flux gauge is described comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator wherein each thermographic layer comprises respective thermographic phosphors. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.
Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.
1989-06-07
A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figs.
Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MaCarthur, C.D.; Cala, G.C.
1991-09-03
A heat flux gauge is described comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figures.
Bacvinskas, W.S.; Bayer, J.E.; Davis, W.W.; Fodor, G.; Kikta, T.J.; Matchett, R.L.; Nilsen, R.J.; Wilczynski, R.
1991-12-31
The present invention is directed to a semi-automatic rod examination gauge for performing a large number of exacting measurements on radioactive fuel rods. The rod examination gauge performs various measurements underwater with remote controlled machinery of high reliability. The rod examination gauge includes instruments and a closed circuit television camera for measuring fuel rod length, free hanging bow measurement, diameter measurement, oxide thickness measurement, cladding defect examination, rod ovality measurement, wear mark depth and volume measurement, as well as visual examination. A control system is provided including a programmable logic controller and a computer for providing a programmed sequence of operations for the rod examination and collection of data.
The game of order and symmetry in matter and in culture
NASA Astrophysics Data System (ADS)
Caglioti, G.
1995-01-01
Symmetry, symmetry breaking and broken symmetries play a central role in science and art, as well as in our daily life. Symmetry - a no-change as the outcome of a change - is synonym of invariance or indiscernibility. As a permanent reference of a structure it is associated with the meaning of the structures and it is fundamental in order to describe them. But symmetry implies the impossibility to discern, that is to measure and to perceive. In order to measure and to perceive, that is to create information and knowledge, symmetry has to be broken. The game of life - a life made of selfreproducing information - develops on the watershed of broken symmetries: an ambiguous and indented ridge of symmetries that break and recover themselves in a continuous series of choices. But even the masterpieces of art of all time run on the same ridge. The musical language, for instance, is a universal language - it can be enjoyed without being translated - just because the two contradictory attitudes of the human soul - the symmetric or dreaming attitude and the "informed" or conscious one - compose themselves in it. Similarly, the most successful trademarks exhibit a measured combination of symmetric and therefore reassuring elements, and elements that break symmetry and, in this way, evoke dynamically the rising of new perspectives. During the conference many examples will be proposed, as well as some suggestive similarities between visual arts, music and science.
Gauge mediation models with adjoint messengers
NASA Astrophysics Data System (ADS)
Gogoladze, Ilia; Mustafayev, Azar; Shafi, Qaisar; Ün, Cem Salih
2016-10-01
We present a class of models in the framework of gauge mediation supersymmetry breaking where the messenger fields transform in the adjoint representation of the standard model gauge symmetry. To avoid unacceptably light right-handed sleptons in the spectrum we introduce a nonzero U (1 )B-L D-term. This leads to an additional contribution to the soft supersymmetry breaking mass terms which makes the right-handed slepton masses compatible with the current experimental bounds. We show that in this framework the observed 125 GeV Higgs boson mass can be accommodated with the sleptons accessible at the LHC, while the squarks and gluinos lie in the multi-TeV range. We also discuss the issue of the fine-tuning and show that the desired relic dark matter abundance can also be accommodated.
7 CFR 868.254 - Broken kernels determination.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 7 2010-01-01 2010-01-01 false Broken kernels determination. 868.254 Section 868.254 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD... Governing Application of Standards § 868.254 Broken kernels determination. Broken kernels shall...
7 CFR 868.304 - Broken kernels determination.
Code of Federal Regulations, 2010 CFR
2010-01-01
... 7 Agriculture 7 2010-01-01 2010-01-01 false Broken kernels determination. 868.304 Section 868.304 Agriculture Regulations of the Department of Agriculture (Continued) GRAIN INSPECTION, PACKERS AND STOCKYARD... Application of Standards § 868.304 Broken kernels determination. Broken kernels shall be determined by the...
Generalized gauge U(1) family symmetry for quarks and leptons
NASA Astrophysics Data System (ADS)
Kownacki, Corey; Ma, Ernest; Pollard, Nicholas; Zakeri, Mohammadreza
2017-03-01
If the standard model of quarks and leptons is extended to include three singlet right-handed neutrinos, then the resulting fermion structure admits an infinite number of anomaly-free solutions with just one simple constraint. Well-known examples satisfying this constraint are B- L, Lμ-Lτ, B- 3Lτ, etc. We derive this simple constraint, and discuss two new examples which offer some insights to the structure of mixing among quark and lepton families, together with their possible verification at the Large Hadron Collider.
E6 inspired supersymmetric models with exact custodial symmetry
NASA Astrophysics Data System (ADS)
Nevzorov, Roman
2013-01-01
The breakdown of E6 gauge symmetry at high energies may lead to supersymmetric models based on the standard model gauge group together with extra U(1)ψ and U(1)χ gauge symmetries. To ensure anomaly cancellation the particle content of these E6 inspired models involves extra exotic states that generically give rise to nondiagonal flavor transitions and rapid proton decay. We argue that a single discrete Z˜2H symmetry can be used to forbid tree-level flavor changing transitions, as well as the most dangerous baryon and lepton number violating operators. We present 5D and 6D orbifold grand unified theory constructions that lead to the E6 inspired supersymmetric models of this type. The breakdown of U(1)ψ and U(1)χ gauge symmetries that preserves E6 matter parity assignment guarantees that ordinary quarks and leptons and their superpartners, as well as the exotic states which originate from 27 representations of E6, survive to low energies. These E6 inspired models contain two dark matter candidates and must also include additional TeV scale vectorlike lepton or vectorlike down-type quark states to render the lightest exotic quark unstable. We examine gauge coupling unification in these models and discuss their implications for collider phenomenology and cosmology.
Spatial symmetry breaking in rapidly rotating convective spherical shells
NASA Technical Reports Server (NTRS)
Zhang, Keke; Schubert, Gerald
1995-01-01
Many problems in geophysical and astrophysical convection systems are characterized by fast rotation and spherical shell geometry. The combined effects of Coriolis forces and spherical shell geometry produce a unique spatial symmetry for the convection pattern in a rapidly rotating spherical shell. In this paper, we first discuss the general spatial symmetries for rotating spherical shell convection. A special model, a spherical shell heated from below, is then used to illustrate how and when the spatial symmetries are broken. Symmetry breaking occurs via a sequence of spatial transitions from the primary conducting state to the complex multiple-layered columnar structure. It is argued that, because of the dominant effects of rotation, the sequence of spatial transitions identified from this particular model is likely to be generally valid. Applications of the spatial symmetry breaking to planetary convection problems are also discussed.
Foliation dependence of black hole apparent horizons in spherical symmetry
NASA Astrophysics Data System (ADS)
Faraoni, Valerio; Ellis, George F. R.; Firouzjaee, Javad T.; Helou, Alexis; Musco, Ilia
2017-01-01
Numerical studies of gravitational collapse to black holes make use of apparent horizons, which are intrinsically foliation dependent. We expose the problem and discuss possible solutions using the Hawking-Hayward quasilocal mass. In spherical symmetry, we present a physically sensible approach to the problem by restricting to spherically symmetric spacetime slicings. In spherical symmetry, the apparent horizons enjoy a restricted gauge independence in any spherically symmetric foliation, but physical quantities associated with them, such as surface gravity and temperature, are fully gauge dependent. The widely used comoving and Kodama foliations, which are of particular interest, are discussed in detail as examples.
Aldrovandi, R.; Pereira, J.G.
1986-05-15
Because it acts on space-time and is not semisimple, the Poincare group cannot lead to a gauge theory of the usual kind. A candidate model is discussed which keeps itself as close as possible to the typical gauge scheme. Its field equations are the Yang-Mills equations for the Poincare group. It is shown that there exists no Lagrangian for these equations.
Local renormalizable gauge theories from nonlocal operators
Capri, M.A.L. Lemes, V.E.R. Sobreiro, R.F. Sorella, S.P. Thibes, R.
2008-03-15
The possibility that nonlocal operators might be added to the Yang-Mills action is investigated. We point out that there exists a class of nonlocal operators which lead to renormalizable gauge theories. These operators turn out to be localizable by means of the introduction of auxiliary fields. The renormalizability is thus ensured by the symmetry content exhibited by the resulting local theory. The example of the nonlocal operator Tr{integral}A{sub {mu}}1/(D{sup 2}) A{sub {mu}} is analyzed in detail. A few remarks on the possible role that these operators might have for confining theories are outlined.
Subleading soft photons and large gauge transformations
NASA Astrophysics Data System (ADS)
Campiglia, Miguel; Laddha, Alok
2016-11-01
Lysov, Pasterski and Strominger have shown how Low's subleading soft photon theorem can be understood as Ward identities of new symmetries of massless QED. In this paper we offer a different perspective and show that there exists a class of large U(1) gauge transformations such that (i) the associated (electric and magnetic) charges can be computed from first principles, (ii) their Ward identities are equivalent to Low's theorem. Our framework paves the way to analyze the sub-subleading theorem in gravity in terms of Ward identities associated to large diffeomorphisms.
Spontaneous CP Violation in E6 GUT with horizontal symmetry
NASA Astrophysics Data System (ADS)
Maekawa, Nobuhiro
2010-02-01
We consider spontaneous CP violation in E6 grand unified theory (GUT) with horizontal symmetry and anomalous U(1)A gauge symmetry in order to solve the SUSY CP problem. To realize the sufficiently small phases of SUSY Higgs mass μ and mixing parameter B, an additional discrete symmetry is introduced. The discrete symmetry plays multiple roles in explaining various things. By the symmetry, the up-type Yukawa couplings become real, which is important in satisfying the Chromo-EDM constraints to the imaginary part of the off-diagonal elements of squark mass matrices, and the down-type Yukawa couplings become complex, which is important in obtaining the Kobayashi-Maskawa phase. Moreover, this symmetry improves the smallness of up quark mass, and reduces the number of O(1) coefficients. One of the interesting predictions is Vub˜γ4, which is quite good agreement with the measured value. This talk is based on the works in Ref. [1].
Higher gauge theories from Lie n-algebras and off-shell covariantization
NASA Astrophysics Data System (ADS)
Carow-Watamura, Ursula; Heller, Marc Andre; Ikeda, Noriaki; Kaneko, Yukio; Watamura, Satoshi
2016-07-01
We analyze higher gauge theories in various dimensions using a supergeometric method based on a differential graded symplectic manifold, called a QP-manifold, which is closely related to the BRST-BV formalism in gauge theories. Extensions of the Lie 2-algebra gauge structure are formulated within the Lie n-algebra induced by the QP-structure. We find that in 5 and 6 dimensions there are special extensions of the gauge algebra. In these cases, a restriction of the gauge symmetry by imposing constraints on the auxiliary gauge fields leads to a covariantized theory. As an example we show that we can obtain an off-shell covariantized higher gauge theory in 5 dimensions, which is similar to the one proposed in [1].
Two-Color Gauge Theory with Novel Infrared Behavior
NASA Astrophysics Data System (ADS)
Appelquist, T.; Brower, R. C.; Buchoff, M. I.; Cheng, M.; Fleming, G. T.; Kiskis, J.; Lin, M. F.; Neil, E. T.; Osborn, J. C.; Rebbi, C.; Schaich, D.; Schroeder, C.; Syritsyn, S.; Voronov, G.; Vranas, P.; Witzel, O.; Lattice Strong Dynamics (LSD) Collaboration
2014-03-01
Using lattice simulations, we study the infrared behavior of a particularly interesting SU(2) gauge theory, with six massless Dirac fermions in the fundamental representation. We compute the running gauge coupling derived nonperturbatively from the Schrödinger functional of the theory, finding no evidence for an infrared fixed point up through gauge couplings g¯2 of order 20. This implies that the theory either is governed in the infrared by a fixed point of considerable strength, unseen so far in nonsupersymmetric gauge theories, or breaks its global chiral symmetries producing a large number of composite Nambu-Goldstone bosons relative to the number of underlying degrees of freedom. Thus either of these phases exhibits novel behavior.
Localization of Gauge Theories on the Three-Sphere
NASA Astrophysics Data System (ADS)
Yaakov, Itamar
We describe the application of localization techniques to the path integral for supersymmetric gauge theories in three dimensions. The localization procedure reduces the computation of the expectation value of BPS observables to a calculation in a matrix model. We describe the ingredients of this model for a general quiver gauge theory and the incorporation of supersymmetric deformations and observables. We use the matrix model expressions to test several duality conjectures for supersymmetric gauge theories. We perform tests of mirror symmetry of three-dimensional quiver gauge theories and of Seiberg-like dualities. Specifically, we explicitly show that the partition functions of the dual pairs, which are highly nontrivial functions of the deformations, agree. We describe extensions of these dualities which can be inferred from the form of the partition functions. We review the application of the matrix model to the study of renormalization group flow and the space of conformal field theories in three dimensions.
Magnetic equivalence of terminal nuclei in the azide anion broken by nuclear spin relaxation
NASA Astrophysics Data System (ADS)
Bernatowicz, P.; Szymański, S.
NMR spectra of water solution of sodium azide selectively 15N labelled in the central position were studied using an iterative least-squares method. In agreement with predictions based on Bloch-Wangsness-Redfield nuclear spin relaxation theory, it is demonstrated that quadrupolar relaxation of the magnetically equivalent terminal 14N (spin-1) nuclei in the azide anion renders the J coupling between these nuclei an observable quantity. In isotropic fluids, this seems to be the first experimental evidence of relaxation-broken magnetic equivalence symmetry.
Relativistic Pseudospin Symmetry
Ginocchio, Joseph N.
2011-05-06
We show that the pseudospin symmetry that Akito Arima discovered many years ago (with collaborators) is a symmetry of the the Dirac Hamiltonian for which the sum of the scalar and vector potentials are a constant. In this paper we discuss some of the implications of this relativistic symmetry and the experimental data that support these predictions. In his original paper Akito also discussed pseudo-U(3) symmetry. We show that pseudo-U(3) symmetry is a symmetry of the Dirac Hamiltonian for which the sum of harmonic oscillator vector and scalar potentials are equal to a constant, and we give the generators of pseudo-U(3) symmetry. Going beyond the mean field we summarize new results on non relativistic shell model Hamiltonians that have pseudospin symmetry and pseudo-orbital angular momentum symmetry as a dynamical symmetries.
Scalar-tensor teleparallel wormholes by Noether symmetries
NASA Astrophysics Data System (ADS)
Bahamonde, Sebastian; Camci, Ugur; Capozziello, Salvatore; Jamil, Mubasher
2016-10-01
A gravitational theory of a scalar field nonminimally coupled with torsion and a boundary term is considered with the aim to construct Lorentzian wormholes. Geometrical parameters including shape and redshift functions are obtained for these solutions. We adopt the formalism of the Noether gauge symmetry approach in order to find symmetries, Lie brackets and invariants (conserved quantities). Furthermore by imposing specific forms of potential function, we are able to calculate metric coefficients and discuss their geometrical behavior.
An Additional Symmetry in the Weinberg-Salam Model
Bakker, B.L.G.; Veselov, A.I.; Zubkov, M.A.
2005-06-01
An additional Z{sub 6} symmetry hidden in the fermion and Higgs sectors of the Standard Model has been found recently. It has a singular nature and is connected to the centers of the SU(3) and SU(2) subgroups of the gauge group. A lattice regularization of the Standard Model was constructed that possesses this symmetry. In this paper, we report our results on the numerical simulation of its electroweak sector.
Broken safety pin in bronchus - Anaesthetic considerations.
Shad, Roona; Agarwal, Aditya
2012-11-01
Safety pins are not commonly aspirated objects in infants and form only a small fraction of all the metallic foreign body (FB) which accounts for 4.4% of all foreign bodies found in tracheobronchial tree. Bronchoscopy procedure has various complications, in addition to failure to remove FB due to its impaction, especially with metallic pointed objects ending up in open surgical removal. Infant with inhaled foreign body are always a challenge to anaesthetist. We had one such case of broken safety pin impacted in the wall of right bronchus of an infant with failure to remove on repeated attempts at rigid bronchoscopy.
Broken safety pin in bronchus - Anaesthetic considerations
Shad, Roona; Agarwal, Aditya
2012-01-01
Safety pins are not commonly aspirated objects in infants and form only a small fraction of all the metallic foreign body (FB) which accounts for 4.4% of all foreign bodies found in tracheobronchial tree. Bronchoscopy procedure has various complications, in addition to failure to remove FB due to its impaction, especially with metallic pointed objects ending up in open surgical removal. Infant with inhaled foreign body are always a challenge to anaesthetist. We had one such case of broken safety pin impacted in the wall of right bronchus of an infant with failure to remove on repeated attempts at rigid bronchoscopy. PMID:23325944
Quantum Chromodynamics -- The Perfect Yang-Mills Gauge Field Theory
NASA Astrophysics Data System (ADS)
Gross, David
David Gross: My talk today is about the most beautiful of all Yang-Mills Theories (non-Abelian gauge theories), the theory of the strong nuclear interactions, Quantum Chromodynamics, QCD. We are celebrating 60 years of the publication of a remarkable paper which introduced the concept of non-Abelian local gauge symmetries, now called the Yang-Mills theory, to physics. In the introduction to this paper it is noted that the usual principle of isotopic spin symmetry is not consistent with the concept of localized fields. This sentence has drawn attention over the years because the usual principle of isotopic spin symmetry is consistent, it is just not satisfactory. The authors, Yang and Mills, introduced a more satisfactory notion of local symmetry which did not require one to rotate (in isotopic spin space) the whole universe at once to achieve the symmetry transformation. Global symmetries are thus are similar to `action at a distance', whereas Yang-Mills theory is manifestly local...
NASA Astrophysics Data System (ADS)
Tareyeva, E. E.; Schelkacheva, T. I.; Chtchelkatchev, N. M.
2013-02-01
We investigate near the point of glass transition the expansion of the free energy corresponding to the generalized Sherrington-Kirkpatrick model with arbitrary diagonal operators Uˆ standing instead of Ising spins. We focus on the case when Uˆ is an operator with broken reflection symmetry. Such a consideration is important for understanding the behavior of spin glass-like phases in a number of real physical systems, mainly in orientational glasses in mixed molecular crystals which present just the case. We build explicitly a full replica symmetry breaking (FRSB) solution of the equations for the orientational glass order parameters when the nonsymmetric part of Uˆ is small. This particular result presents a counterexample in the context of usually adopted conjecture of the absence of FRSB solution in systems with no reflection symmetry.
NASA Astrophysics Data System (ADS)
Huang, Changyu; Huang, Yong-Chang; Zhou, Bao-Hua
2015-09-01
We investigate the inner structure of a general S U (2 ) [naturally including S O (3 )] symmetry system—the fermion-gauge field interaction system—and achieve naturally a set of gauge-invariant spin and orbital angular momentum operators of fermion and gauge fields by Noether's theorem in general field theory. Some new relations concerning non-Abelian field strengths are discovered, e.g., the covariant transverse condition, covariant parallel condition (i.e., non-Abelian divergence, non-Abelian curl), and simplified S U (2 ) Coulomb theorem. And we show that the condition that Chen et al. obtained to construct their gauge-invariant angular momentum operators is a result of some fundamental equations in the general field theory. The results obtained in this paper present a new perspective for looking at the overall structure of the gauge field, and provide a new viewpoint to the final resolution of the nucleon spin crisis in the general field theory. Especially, the achieved theory in this paper can calculate the strong interactions with isospin symmetry and solves the serious problem without gauge-invariant angular momenta in strong interaction systems with isospin symmetry, and then the achieved predictions in the calculations can be exactly measured by particle physics experiments due to their gauge invariant properties.
Residual Weyl symmetry out of conformal geometry and its BRST structure
NASA Astrophysics Data System (ADS)
François, J.; Lazzarini, S.; Masson, T.
2015-09-01
The conformal structure of second order in m-dimensions together with the so-called (normal) conformal Cartan connection, is considered as a framework for gauge theories. The dressing field scheme presented in a previous work amounts to a decoupling of both the inversion and the Lorentz symmetries such that the residual gauge symmetry is the Weyl symmetry. On the one hand, it provides straightforwardly the Riemannian parametrization of the normal conformal Cartan connection and its curvature. On the other hand, it also provides the finite transformation laws under the Weyl rescaling of the various geometric objects involved. Subsequently, the dressing field method is shown to fit the BRST differential algebra treatment of infinitesimal gauge symmetry. The dressed ghost field encoding the residual Weyl symmetry is presented. The related so-called algebraic connection supplies relevant combinations found in the literature in the algebraic study of the Weyl anomaly.
Is space-time symmetry a suitable generalization of parity-time symmetry?
Amore, Paolo; Fernández, Francisco M.; Garcia, Javier
2014-11-15
We discuss space-time symmetric Hamiltonian operators of the form H=H{sub 0}+igH{sup ′}, where H{sub 0} is Hermitian and g real. H{sub 0} is invariant under the unitary operations of a point group G while H{sup ′} is invariant under transformation by elements of a subgroup G{sup ′} of G. If G exhibits irreducible representations of dimension greater than unity, then it is possible that H has complex eigenvalues for sufficiently small nonzero values of g. In the particular case that H is parity-time symmetric then it appears to exhibit real eigenvalues for all 0
Absorption of solar radiation in broken clouds
Zuev, V.E.; Titov, G.A.; Zhuravleva, T.B.
1996-04-01
It is recognized now that the plane-parallel model unsatisfactorily describes the transfer of radiation through broken clouds and that, consequently, the radiation codes of general circulation models (GCMs) must be refined. However, before any refinement in a GCM code is made, it is necessary to investigate the dependence of radiative characteristics on the effects caused by the random geometry of cloud fields. Such studies for mean fluxes of downwelling and upwelling solar radiation in the visible and near-infrared (IR) spectral range were performed by Zuev et al. In this work, we investigate the mean spectral and integrated absorption of solar radiation by broken clouds (in what follows, the term {open_quotes}mean{close_quotes} will be implied but not used, for convenience). To evaluate the potential effect of stochastic geometry, we will compare the absorption by cumulus (0.5 {le} {gamma} {le} 2) to that by equivalent stratus ({gamma} <<1) clouds; here {gamma} = H/D, H is the cloud layer thickness and D the characteristic horizontal cloud size. The equivalent stratus clouds differ from cumulus only in the aspect ratio {gamma}, all the other parameters coinciding.
Non-Hermitian Hamiltonians with unitary and antiunitary symmetries
Fernández, Francisco M. Garcia, Javier
2014-03-15
We analyse several non-Hermitian Hamiltonians with antiunitary symmetry from the point of view of their point-group symmetry. It enables us to predict the degeneracy of the energy levels and to reduce the dimension of the matrices necessary for the diagonalization of the Hamiltonian in a given basis set. We can also classify the solutions according to the irreducible representations of the point group and thus analyse their properties separately. One of the main results of this paper is that some PT-symmetric Hamiltonians with point-group symmetry C{sub 2v} exhibit complex eigenvalues for all values of a potential parameter. In such cases the PT phase transition takes place at the trivial Hermitian limit which suggests that the phenomenon is not robust. Point-group symmetry enables us to explain such anomalous behaviour and to choose a suitable antiunitary operator for the PT symmetry. -- Highlights: •PT-symmetric Hamiltonians exhibit real eigenvalues when PT symmetry is unbroken. •PT-symmetric multidimensional oscillators appear to show PT phase transitions. •This transition was conjectured to be a high-energy phenomenon. •We show that point group symmetry is useful for predicting broken PT symmetry in multidimensional oscillators. •PT-symmetric oscillators with C{sub 2v} symmetry exhibit phase transitions at the trivial Hermitian limit.
Poincare gauge in electrodynamics
Brittin, W.E.; Smythe, W.R.; Wyss, W.
1982-08-01
The gauge presented here, which we call the Poincare gauge, is a generalization of the well-known expressions phi = -rxE/sub 0/ and A = 1/2 B/sub 0/ x r for the scalar and vector potentials which describe static, uniform electric and magnetic fields. This gauge provides a direct method for calculating a vector potential for any given static or dynamic magnetic field. After we establish the validity and generality of this gauge, we use it to produce a simple and unambiguous method of computing the flux linking an arbitrary knotted and twisted closed circuit. The magnetic flux linking the curve bounding a Moebius band is computed as a simple example. Arguments are then presented that physics students should have the opportunity of learning early in their curriculum modern geometric approaches to physics. (The language of exterior calculus may be as important to future physics as vector calculus was to the past.) Finally, an appendix illustrates how the Poincare gauge (and others) may be derived from Poincare's lemma relating exact and closed exterior differential forms.
The phenomenoogy of extended gauge and higgs sectors at the LHC
Peterson, Andrea Dawn
2008-01-01
We consider prospects for detecting and measuring the properties of Z', W' and heavy Higgs bosons at the Large Hadron Collider (LHC). These particles are all well-motivated heavier counterparts to known SM particles. Z' and W0 bosons arise when the SM gauge group is extended with additional U(1) or SU(2) factors. Heavy Higgs bosons are a feature of many models, including the Two Higgs Doublet Model (2HDM), supersymmetric (SUSY) models, and W' and Z' models. First, we consider a number of common Z' models and present next-to-leading (NLO) and next-to-next-to-leading order (NNLO) predictions for the cross section, forwardbackward asymmetry, and rapidity distributions. We discuss methods for measuring the couplings of the Z' and distinguishing among models. Z' bosons with masses around 5 TeV should be detectable at the LHC, and the couplings of a 2.5 TeV Z' could be measured within 0.1π with a luminosity of 1 ab^{-1}. We also consider a hidden sector Z' that couples to standard model fermions via kinetic and mass mixing and serves as a mediator of isospin-violating interactions with dark matter. We combine the results of LHC Z' searches and dark matter direct detection experiments with global electroweak data to obtain mass-dependent constraints on the model parameters. Next, we consider the fact that extra broken gauge symmetries are often accompanied by extended scalar sectors. If the masses of new Higgs particles are not too large, the W' bosons may decay into heavy Higgs particles, providing new possibilities for W' detection. We consider a simple scenario where the W' couplings to fermions are suppressed, making decays to scalar pairs the dominant decay mode. Potential final states include one or two gauge bosons plus missing energy. Finally, we turn our attention to Higgs pair production in the 2HDM. Higgs pair production is a valuable tool for measuring the triscalar couplings of the scalar potential. We consider both hh resonant production and h
Flavored Peccei-Quinn symmetry
NASA Astrophysics Data System (ADS)
Ahn, Y. H.
2015-03-01
In an attempt to uncover any underlying physics in the standard model (SM), we suggest a μ - τ power law in the lepton sector, such that relatively large 13 mixing angle with bilarge ones can be derived. On the basis of this, we propose a neat and economical model for both the fermion mass hierarchy problem of the SM and a solution to the strong charge parity (C P ) problem, in a way that no domain wall problem occurs, based on A4×U (1 )X symmetry in a supersymmetric framework. Here we refer to the global U (1 )X symmetry that can explain the above problems as "flavored Peccei-Quinn symmetry." In the model, a direct coupling of the SM gauge singlet flavon fields responsible for spontaneous symmetry breaking to ordinary quarks and leptons, both of which are charged under U (1 )X, comes to pass through Yukawa interactions, and all vacuum expectation values breaking the symmetries are connected to each other. So the scale of Peccei-Quinn symmetry breaking is shown to be roughly located around the 1 012 GeV section through its connection to the fermion masses. The model predictions are shown to lie on the testable regions in the very near future through on-going experiments for neutrino oscillation, neutrinoless double beta decay, and the axion. We examine the model predictions, arisen from the μ - τ power law, on leptonic C P violation, neutrinoless double beta decay, and atmospheric mixing angle, and show that the fermion mass and mixing hierarchies are in good agreement with the present data. Interestingly, we show the model predictions on the axion mass ma≃2.53 ×1 0-5 eV and the axion coupling to photon ga γ γ≃1.33 ×1 0-15 GeV-1 . And subsequently the square of the ratio between them is shown to be one or two orders of magnitude lower than that of the conventional axion model.
Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.
1991-04-09
A heat flux gauge is disclosed comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figures.
NASA Astrophysics Data System (ADS)
Chaichian, M.; Montonen, C.; Pérez Rojas, H.
1991-03-01
The completely different conservation properties of charges associated to unbroken and broken symmetries are discussed. The impossibility of establishing a conservation law for nondegenerate Hilbert space representations in the broken case leads to a reciprocal of Coleman's theorem. The quantum statistical implication is that these charges cannot be introduced as conserved operators in the density matrix. On leave of absence from Instituto de Cibernética, Matemática y Fisica (ICIMAF), Calle 0#8, Vedado, Havana 4, Cuba.
Effective theory and emergent SU(2 ) symmetry in the flat bands of attractive Hubbard models
NASA Astrophysics Data System (ADS)
Tovmasyan, Murad; Peotta, Sebastiano; Törmä, Päivi; Huber, Sebastian D.
2016-12-01
In a partially filled flat Bloch band electrons do not have a well defined Fermi surface and hence the low-energy theory is not a Fermi liquid. Nevertheless, under the influence of an attractive interaction, a superconductor well described by the Bardeen-Cooper-Schrieffer (BCS) wave function can arise. Here we study the low-energy effective Hamiltonian of a generic Hubbard model with a flat band. We obtain an effective Hamiltonian for the flat band physics by eliminating higher-lying bands via the perturbative Schrieffer-Wolff transformation. At first order in the interaction energy we recover the usual procedure of projecting the interaction term onto the flat band Wannier functions. We show that the BCS wave function is the exact ground state of the projected interaction Hamiltonian, if a simple uniform pairing condition on the single-particle states is satisfied, and that the compressibility is diverging as a consequence of an emergent SU(2 ) symmetry. This symmetry is broken by second-order interband transitions resulting in a finite compressibility, which we illustrate for a one-dimensional ladder with two perfectly flat bands. These results motivate a further approximation leading to an effective ferromagnetic Heisenberg model. The gauge-invariant result for the superfluid weight of a flat band can be obtained from the ferromagnetic Heisenberg model only if the maximally localized Wannier functions in the Marzari-Vanderbilt sense are used. Finally, we prove an important inequality D ≥W2 between the Drude weight D and the winding number W , which guarantees ballistic transport for topologically nontrivial flat bands in one dimension.
Mirror symmetry for Enriques surfaces
NASA Astrophysics Data System (ADS)
Lakuriqi, Enkeleida
In this thesis, we investigate three separate but related projects. In the first one, we describe the geometric backgrounds of Type II string theory which are given by Enriques surfaces and their mirrors. We also study the effect of various string dualities on such backgrounds, in particular phase change in Gauged Linear Sigma Models and mirror symmetry. In the second project, we investigate special Kahler geometry in order to find canonical coordinates on the moduli of generalised Calabi-Yau spaces and the associated (2, 2) superconformal field theories. In the third project, we develop a general technique for computing the massless spectrum of (0, 2) quantum field theory compactified on a proper stack or an orbifold. We produce general formulas for the contribution of the twisted sectors and compute specific examples of compactifications on gerbes on projective spaces and Calabi-Yau threefolds.
Surface charge algebra in gauge theories and thermodynamic integrability
NASA Astrophysics Data System (ADS)
Barnich, Glenn; Compère, Geoffrey
2008-04-01
Surface charges and their algebra in interacting Lagrangian gauge field theories are constructed out of the underlying linearized theory using techniques from the variational calculus. In the case of exact solutions and symmetries, the surface charges are interpreted as a Pfaff system. Integrability is governed by Frobenius' theorem and the charges associated with the derived symmetry algebra are shown to vanish. In the asymptotic context, we provide a generalized covariant derivation of the result that the representation of the asymptotic symmetry algebra through charges may be centrally extended. Comparison with Hamiltonian and covariant phase space methods is made. All approaches are shown to agree for exact solutions and symmetries while there are differences in the asymptotic context.
Anomalous discrete symmetries in three dimensions and group cohomology.
Kapustin, Anton; Thorngren, Ryan
2014-06-13
We study 't Hooft anomalies for a global discrete internal symmetry G. We construct examples of bosonic field theories in three dimensions with a nonvanishing 't Hooft anomaly for a discrete global symmetry. We also construct field theories in three dimensions with a global discrete internal symmetry G(1) × G(2) such that gauging G(1) necessarily breaks G(2) and vice versa. This is analogous to the Adler-Bell-Jackiw axial anomaly in four dimensions and parity anomaly in three dimensions.
Determining triple gauge boson couplings from Higgs data.
Corbett, Tyler; Éboli, O J P; Gonzalez-Fraile, J; Gonzalez-Garcia, M C
2013-07-05
In the framework of effective Lagrangians with the SU(2)(L)×U(1)(Y) symmetry linearly realized, modifications of the couplings of the Higgs field to the electroweak gauge bosons are related to anomalous triple gauge couplings (TGCs). Here, we show that the analysis of the latest Higgs boson production data at the LHC and Tevatron give rise to strong bounds on TGCs that are complementary to those from direct TGC analysis. We present the constraints on TGCs obtained by combining all available data on direct TGC studies and on Higgs production analysis.
Symmetries in Three-Dimensional Superconformal Quantum Field Theories
NASA Astrophysics Data System (ADS)
Bashkirov, Denis
Many examples of gauge-gravity duality and quantum equivalences of different-looking three-dimensional Quantum Field Theories indicate the existence of continuous symmetries whose currents are not built from elementary, or perturbative, fields used to write down the Lagrangian. These symmetries are called hidden or nonperturbative. We describe a method for studying continuous symmetries in a large class of three-dimensional supersymmetric gauge theories which, in particular, enables one to explore nonperturbative global symmetries and supersymmetries. As an application of the method, we prove conjectured supersymmetry enhancement in strongly coupled ABJM theory from N = 6 to N = 8 and find additional nonperturbative evidence for its duality to the N = 8 U(N) SYM theory for the minimal value of the Chern-Simons coupling. Hidden supersymmetry is also shown to occur in N = 4 d = 3 SQCD with one fundamental and one adjoint hypermultiplets. An infinite family of N = 6 d = 3 ABJ theories is proved to have hidden N = 8 superconformal symmetry and hidden parity on the quantum level. We test several conjectural dualities between ABJ theories and theories proposed by Bagger and Lambert, and Gustavsson by comparing superconformal indices of these theories. Comparison of superconformal indices is also used to test dualities between N = 2 d = 3 theories proposed by Aharony, the analysis of whose chiral rings teaches some general lessons about nonperturbative chiral operators of strongly coupled 3d supersymmetric gauge theories. As another application of our method we consider examples of hidden global symmetries in a class of quiver three-dimensional N = 4 superconformal gauge theories. Finally, we point out to the relations between some basic propeties of superconformal N ≥ 6 theories and their symmetries. The results presented in this thesis were obtained in a series of papers [1, 2, 3, 4, 5].
A confining model for charmonium and new gauge-invariant field equations
NASA Astrophysics Data System (ADS)
Hsu, Jong-Ping
2014-06-01
We discuss a confining model for charmonium in which the attractive force are derived from a new type of gauge field equation with a generalized SU3 gauge symmetry. The new gauge transformations involve non-integrable phase factors with vector gauge functions ω {ω/ a }( x). These transformations reduce to the usual SU3 gauge transformations in the special case ω {μ/ a }( x) = ∂ μ ξ a ( x). Such a generalized gauge symmetry leads to the fourth-order equations for new gauge fields and to the linear confining potentials. The fourth-order field equation implies that the corresponding massless gauge boson has non-definite energy. However, the new gauge boson is permanently confined in a quark system by the linear potential. We use the empirical potentials of the Cornell group for charmonium to obtain the coupling strength f 2/(4 π) ≈ 0.19 for the strong interaction. Such a confining model of quark dynamics could be compatible with perturbation. The model can be applied to other quark-antiquark systems.
Gauge Theories on the Coulomb Branch
NASA Astrophysics Data System (ADS)
Schwarz, John H.
We construct the world-volume action of a probe D3-brane in AdS5 × S5 with N units of flux. It has the field content, symmetries, and dualities of the U(1) factor of 𝒩 = 4 U(N + 1) super Yang-Mills theory, spontaneously broken to U(N) × U(1) by being on the Coulomb branch, with the massive fields integrated out. This motivates the conjecture that it is the exact effective action, called a highly effective action (HEA). We construct an SL(2, Z) multiplet of BPS soliton solutions of the D3-brane theory (the conjectured HEA) and show that they reproduce the electrically charged massive states that have been integrated out as well as magnetic monopoles and dyons. Their charges are uniformly spread on a spherical surface, called a soliton bubble, which is interpreted as a phase boundary.
Operational teledermatology in Broken Hill, rural Australia.
See, Adrian; Lim, Adrian C; Le, Katie; See, Jo-Ann; Shumack, Stephen P
2005-08-01
From January 2001 to January 2002, Broken Hill, New South Wales, served as a trial site for teledermatology as one method of access to dermatologists. Fourteen participating general practitioners referred 46 patients making up 48 teledermatology cases. The mean diagnostic agreement between general practitioners and dermatologists was 35% and 50% for primary and differential diagnoses, respectively. Teledermatology patients formed 12% of the collectively referred dermatology patients (outpatients and teledermatology). In this project, high patient and general practitioner acceptability and positive medical outcomes confirm the value of rural teledermatology. However, this project also revealed unexpected barriers and pitfalls in the effective operation of rural teledermatology. Lack of education of participants, inertia among potential users and patient inconvenience are issues that may adversely affect the effective implementation of rural teledermatology.
Effective action of softly broken supersymmetric theories
Nibbelink, Stefan Groot; Nyawelo, Tino S.
2007-02-15
We study the renormalization of (softly) broken supersymmetric theories at the one loop level in detail. We perform this analysis in a superspace approach in which the supersymmetry breaking interactions are parametrized using spurion insertions. We comment on the uniqueness of this parametrization. We compute the one loop renormalization of such theories by calculating superspace vacuum graphs with multiple spurion insertions. To perform this computation efficiently we develop algebraic properties of spurion operators, that naturally arise because the spurions are often surrounded by superspace projection operators. Our results are general apart from the restrictions that higher super covariant derivative terms and some finite effects due to noncommutativity of superfield dependent mass matrices are ignored. One of the soft potentials induces renormalization of the Kaehler potential.
Remarks on holography with broken Lorentz invariance
NASA Astrophysics Data System (ADS)
Gordeli, Ivan; Koroteev, Peter
2009-12-01
Recently a family of solutions of Einstein equations in backgrounds with broken Lorentz invariance was found. We show that the gravitational solution recently obtained by Kachru et al. is a part of the former solution which was derived earlier in the framework of extra-dimensional theories. We show how the energy-momentum and Einstein tensors are related and establish a correspondence between parameters which govern Lorentz invariance violation. Then we demonstrate that scaling behavior of two point correlation functions of local operators in scalar field theory is reproduced correctly for two cases with critical values of scaling parameters. Therefore, we complete the dictionary of “tree-level” duality for all known solutions of the bulk theory. In the end we speculate on relations between renormalization group flow of a boundary theory and asymptotic behavior of gravitational solutions in the bulk.
Singlet-stabilized minimal gauge mediation
NASA Astrophysics Data System (ADS)
Curtin, David; Tsai, Yuhsin
2011-04-01
We propose singlet-stabilized minimal gauge mediation as a simple Intriligator, Seiberg and Shih-based model of direct gauge mediation which avoids both light gauginos and Landau poles. The hidden sector is a massive s-confining supersymmetric QCD that is distinguished by a minimal SU(5) flavor group. The uplifted vacuum is stabilized by coupling the meson to an additional singlet sector with its own U(1) gauge symmetry via nonrenormalizable interactions suppressed by a higher scale ΛUV in the electric theory. This generates a nonzero vacuum expectation value for the singlet meson via the inverted hierarchy mechanism, but requires tuning to a precision ˜(Λ/ΛUV)2, which is ˜10-4. In the course of this analysis we also outline some simple model-building rules for stabilizing uplifted-ISS models, which lead us to conclude that meson deformations are required (or at least heavily favored) to stabilize the adjoint component of the magnetic meson.
Light-Front Quantization of Gauge Theories
Brodskey, Stanley
2002-12-01
Light-front wavefunctions provide a frame-independent representation of hadrons in terms of their physical quark and gluon degrees of freedom. The light-front Hamiltonian formalism provides new nonperturbative methods for obtaining the QCD spectrum and eigensolutions, including resolvant methods, variational techniques, and discretized light-front quantization. A new method for quantizing gauge theories in light-cone gauge using Dirac brackets to implement constraints is presented. In the case of the electroweak theory, this method of light-front quantization leads to a unitary and renormalizable theory of massive gauge particles, automatically incorporating the Lorentz and 't Hooft conditions as well as the Goldstone boson equivalence theorem. Spontaneous symmetry breaking is represented by the appearance of zero modes of the Higgs field leaving the light-front vacuum equal to the perturbative vacuum. I also discuss an ''event amplitude generator'' for automatically computing renormalized amplitudes in perturbation theory. The importance of final-state interactions for the interpretation of diffraction, shadowing, and single-spin asymmetries in inclusive reactions such as deep inelastic lepton-hadron scattering is emphasized.
Does three-dimensional electromagnetic field inherit the spacetime symmetries?
NASA Astrophysics Data System (ADS)
Cvitan, M.; Dominis Prester, P.; Smolić, I.
2016-04-01
We prove that the electromagnetic field in a (1+2)-dimensional spacetime necessarily inherits the symmetries of the spacetime metric in a large class of generalized Einstein-Maxwell theories. The Lagrangians of the studied theories have general diff-covariant gravitational part and include both the gravitational and the gauge Chern-Simons terms.
Mechanisms of chiral symmetry breaking in QCD: A lattice perspective
NASA Astrophysics Data System (ADS)
Giusti, Leonardo
2016-01-01
I briefly review two recent studies on chiral symmetry breaking in QCD: (a) a computation of the spectral density of the Dirac operator in QCD Lite, (b) a precise determination of the topological charge distribution in the SU(3) Yang-Mills theory as defined by evolving the fundamental gauge field with the Yang-Mills gradient flow equation.
Introduction to gauge theories of the strong, weak, and electromagnetic interactions
Quigg, C.
1980-07-01
The plan of these notes is as follows. Chapter 1 is devoted to a brief evocative review of current beliefs and prejudices that form the context for the discussion to follow. The idea of Gauge Invariance is introduced in Chapter 2, and the connection between conservation laws and symmetries of the Lagrangian is recalled. Non-Abelian gauge field theories are constructed in Chapter 3, by analogy with the familiar case of electromagnetism. The Yang-Mills theory based upon isospin symmetry is constructed explicitly, and the generalization is made to other gauge groups. Chapter 4 is concerned with spontaneous symmetry breaking and the phenomena that occur in the presence or absence of local gauge symmetries. The existence of massless scalar fields (Goldstone particles) and their metamorphosis by means of the Higgs mechanism are illustrated by simple examples. The Weinberg-Salam model is presented in Chapter 5, and a brief resume of applications to experiment is given. Quantum Chromodynamics, the gauge theory of colored quarks and gluons, is developed in Chapter 6. Asymptotic freedom is derived schematically, and a few simple applications of perturbative QCD ae exhibited. Details of the conjectured confinement mechanism are omitted. The strategy of grand unified theories of the strong, weak, and electromagnetic interactions is laid out in Chapter 7. Some properties and consequences of the minimal unifying group SU(5) are presented, and the gauge hierarchy problem is introduced in passing. The final chapter contains an essay on the current outlook: aspirations, unanswered questions, and bold scenarios.
Magnetic Field Response and Chiral Symmetry of Time Reversal Invariant Topological Superconductors
NASA Astrophysics Data System (ADS)
Dumitrescu, Eugen; Sau, Jay D.; Tewari, Sumtanta
2014-03-01
We study the magnetic ?eld response of the Majorana Kramers pairs of a one-dimensional time-reversal invariant (TRI) superconductors (class DIII) with or without a coexisting chirality symmetry. For unbroken TR and chirality invariance the parameter regimes for nontrivial values of the (Z2) DIII-invariant and the (Z) BDI chiral invariant coincide. However, broken TR may or may not be accompanied by broken chirality, and if chiral symmetry is unbroken the pair of Majorana fermions (MFs) at a given end survives the loss of TR symmetry in an entire plane perpendicular to the spin-orbit coupling field. Conversely, we show that broken chirality may or may not be accompanied by broken TR, and if TR is unbroken, the pair of MFs survives the loss of broken chirality. In addition to explaining the anomalous magnetic field response of all the DIII class TS systems proposed in the literature, we provide a realistic route to engineer a ``true'' TR-invariant TS, whose pair of MFs at each end is split by an applied Zeeman field in arbitrary direction. We also prove that, quite generally, the splitting of the MFs by TR-breaking fields in TRI superconductors is highly anisotropic in spin space, even in the absence of the topological chiral symmetry.
Rasin, A.
1994-04-01
We discuss the idea of approximate flavor symmetries. Relations between approximate flavor symmetries and natural flavor conservation and democracy models is explored. Implications for neutrino physics are also discussed.
Rizzo, T.G.
1995-02-01
Present and future prospects for the discovery of new gauge bosons, Z{prime} and W{prime}, are reviewed. Particular attention is paid to hadron and e{sup +}e{sup {minus}} collider searches for the W{prime} of the Left-Right Symmetric Model.
Performance improvements of symmetry-breaking reflector structures in nonimaging devices
Winston, Roland
2004-01-13
A structure and method for providing a broken symmetry reflector structure for a solar concentrator device. The component of the optical direction vector along the symmetry axis is conserved for all rays propagated through a translationally symmetric optical device. This quantity, referred to as the translational skew invariant, is conserved in rotationally symmetric optical systems. Performance limits for translationally symmetric nonimaging optical devices are derived from the distributions of the translational skew invariant for the optical source and for the target to which flux is to be transferred. A numerically optimized non-tracking solar concentrator utilizing symmetry-breaking reflector structures can overcome the performance limits associated with translational symmetry.
Electromagnetic duality symmetry and helicity conservation for the macroscopic Maxwell's equations.
Fernandez-Corbaton, Ivan; Zambrana-Puyalto, Xavier; Tischler, Nora; Vidal, Xavier; Juan, Mathieu L; Molina-Terriza, Gabriel
2013-08-09
In this Letter, we show that the electromagnetic duality symmetry, broken in the microscopic Maxwell's equations by the presence of charges, can be restored for the macroscopic Maxwell's equations. The restoration of this symmetry is shown to be independent of the geometry of the problem. These results provide a tool for the study of light-matter interactions within the framework of symmetries and conservation laws. We illustrate its use by determining the helicity content of the natural modes of structures possessing spatial inversion symmetries and by elucidating the root causes for some surprising effects in the scattering off magnetic spheres.
Exposing local symmetries in distorted driven lattices via time-averaged invariants
NASA Astrophysics Data System (ADS)
Wulf, T.; Morfonios, C. V.; Diakonos, F. K.; Schmelcher, P.
2016-05-01
Time-averaged two-point currents are derived and shown to be spatially invariant within domains of local translation or inversion symmetry for arbitrary time-periodic quantum systems in one dimension. These currents are shown to provide a valuable tool for detecting deformations of a spatial symmetry in static and driven lattices. In the static case the invariance of the two-point currents is related to the presence of time-reversal invariance and/or probability current conservation. The obtained insights into the wave functions are further exploited for a symmetry-based convergence check which is applicable for globally broken but locally retained potential symmetries.
Neutrinos and flavor symmetries
Tanimoto, Morimitsu
2015-07-15
We discuss the recent progress of flavor models with the non-Abelian discrete symmetry in the lepton sector focusing on the θ{sub 13} and CP violating phase. In both direct approach and indirect approach of the flavor symmetry, the non-vanishing θ{sub 13} is predictable. The flavor symmetry with the generalised CP symmetry can also predicts the CP violating phase. We show the phenomenological analyses of neutrino mixing for the typical flavor models.
D0- and D1-branes with κ- and κ+ extended symmetry
NASA Astrophysics Data System (ADS)
Moshe, Moshe; Sakai, Norisuke
2000-10-01
D0-brane (D-particle) and D1-brane actions possess first and second class constraints that result in local κ symmetry. The κ symmetry of the D-particle and the D1-brane is extended here into a larger symmetry (κ- and κ+) in a larger phase space by turning second class constraints into first class constraints. Different gauge fixings of these symmetries result in different presentations of these systems while a ``unitary'' gauge fixing of the new κ+ symmetry retrieves the original action with κ-=κ symmetry. For a D1-brane our extended phase space makes all constraints into first class constraints in the case of a vanishing world sheet electric field [namely, (0,1) string].
SL(2, z) Action on Three-Dimensional Conformal Field Theories with Abelian Symmetry
NASA Astrophysics Data System (ADS)
Witten, Edward
On the space of three-dimensional conformal field theories with U(1) symmetry and a chosen coupling to a background gauge field, there is a natural action of the group SL(2, Z). The generator S of SL(2, Z) acts by letting the background gauge field become dynamical, an operation considered recently by Kapustin and Strassler in explaining three-dimensional mirror symmetry. The other generator T acts by shifting the Chern-Simons coupling of the background field. This SL(2, Z) action in three dimensions is related by the AdS/CFT correspondence to SL(2, Z) duality of low energy U(1) gauge fields in four dimensions.