Symmetries and mass splittings QCD 2 coupled to adjoint fermions

NASA Astrophysics Data System (ADS)

Boorstein, Joshua; Kutasov, David

1994-06-01

Two-dimensional QCD coupled to fermions in the adjoint representation of the gauge group SU( N), a useful toy model of QCD strings, is supersymmetric for a certain ratio of quark mass and gauge coupling constant. Here we study the theory in the vicinity of the supersymmetric point; in particular we exhibit the algebraic structure of the model and show that the mass splittings as one moves away from the supersymmetric point obey a universal relation of the form Mi2(B)- Mi2(F) = Miδm + O( δm3). We discuss the connection of this relation to string and quark model expectations and verify it numerically for large N. At least for low lying states the O( δm3) corrections are extremely small. We also discuss a natural generalization of QCD 2 with an infinite number of couplings, which preserves SUSY. This leads to a Landau-Ginzburg description of the theory, and may be useful for defining a scaling limit in which smooth worldsheets appear.

Conformal versus confining scenario in SU(2) with adjoint fermions

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

Del Debbio, L.; Pica, C.; Lucini, B.

2009-10-01

The masses of the lowest-lying states in the meson and in the gluonic sector of an SU(2) gauge theory with two Dirac flavors in the adjoint representation are measured on the lattice at a fixed value of the lattice coupling {beta}=4/g{sub 0}{sup 2}=2.25 for values of the bare fermion mass m{sub 0} that span a range between the quenched regime and the massless limit, and for various lattice volumes. Even for light constituent fermions the lightest glueballs are found to be lighter than the lightest mesons. Moreover, the string tension between two static fundamental sources strongly depends on the massmore » of the dynamical fermions and becomes of the order of the inverse squared lattice linear size before the chiral limit is reached. The implications of these findings for the phase of the theory in the massless limit are discussed and a strategy for discriminating between the (near-)conformal and the confining scenario is outlined.« less

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

NASA Astrophysics Data System (ADS)

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

2014-07-01

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

Amplitudes in the N=4 supersymmetric Yang-Mills theory from quantum geometry of momentum space

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

Gorsky, A.

We discuss multiloop maximally helicity violating amplitudes in the N=4 supersymmetric Yang-Mills theory in terms of effective gravity in the momentum space with IR regulator branes as degrees of freedom. Kinematical invariants of external particles yield the moduli spaces of complex or Kahler structures which are the playgrounds for the Kodaira-Spencer or Kahler type gravity. We suggest fermionic representation of the loop maximally helicity violating amplitudes in the N=4 supersymmetric Yang-Mills theory assuming the identification of the IR regulator branes with Kodaira-Spencer fermions in the B model and Lagrangian branes in the A model. The two-easy mass box diagram ismore » related to the correlator of fermionic currents on the spectral curve in the B model or hyperbolic volume in the A model and it plays the role of a building block in the whole picture. The Bern-Dixon-Smirnov-like ansatz has the interpretation as the semiclassical limit of a fermionic correlator. It is argued that fermionic representation implies a kind of integrability on the moduli spaces. We conjecture the interpretation of the reggeon degrees of freedom in terms of the open strings stretched between the IR regulator branes.« less

String theory origin of constrained multiplets

NASA Astrophysics Data System (ADS)

Kallosh, Renata; Vercnocke, Bert; Wrase, Timm

2016-09-01

We study the non-linearly realized spontaneously broken supersymmetry of the (anti-)D3-brane action in type IIB string theory. The worldvolume fields are one vector A μ , three complex scalars ϕ i and four 4d fermions λ 0, λ i. These transform, in addition to the more familiar {N}=4 linear supersymmetry, also under 16 spontaneously broken, non-linearly realized supersymmetries. We argue that the worldvolume fields can be packaged into the following constrained 4d non-linear {N}=1 multiplets: four chiral multiplets S, Y i that satisfy S 2 = SY i =0 and contain the worldvolume fermions λ 0 and λ i ; and four chiral multiplets W α , H i that satisfy S{W}_{α }=S{overline{D}}_{overset{\\cdotp }{α }}{overline{H}}^{overline{imath}}=0 and contain the vector A μ and the scalars ϕ i . We also discuss how placing an anti-D3-brane on top of intersecting O7-planes can lead to an orthogonal multiplet Φ that satisfies S(Φ -overline{Φ})=0 , which is particularly interesting for inflationary cosmology.

Grand Unification as a Bridge Between String Theory and Phenomenology

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

Pati, Jogesh C.

2006-06-09

In the first part of the talk, I explain what empirical evidence points to the need for having an effective grand unification-like symmetry possessing the symmetry SU(4)-color in 4D. If one assumes the premises of a future predictive theory including gravity--be it string/M theory or a reincarnation--this evidence then suggests that such a theory should lead to an effective grand unification-like symmetry as above in 4D, near the string-GUT-scale, rather than the standard model symmetry. Advantages of an effective supersymmetric G(224) = SU(2){sub L} x SU(2){sub R} x SU(4){sup c} or SO(10) symmetry in 4D in explaining (1) observed neutrinomore » oscillations, (2) baryogenesis via leptogenesis, and (3) certain fermion mass-relations are noted. And certain distinguishing tests of a SUSY G(224) or SO(10)-framework involving CP and flavor violations (as in {mu} {yields} e{gamma}, {tau} {yields} {mu}{gamma}, edm's of the neutron and the electron) as well as proton decay are briefly mentioned. Recalling some of the successes we have had in our understanding of nature so far, and the current difficulties of string/M theory as regards the large multiplicity of string vacua, some comments are made on the traditional goal of understanding vis a vis the recently evolved view of landscape and anthropism.« less

On the spectrum of gauge/gravity duals with reduced supersymmetry

NASA Astrophysics Data System (ADS)

Solovyov, Alexander

The topic of the present thesis is the study of some examples in gauge/string duality. We carefully study the orbifold gauge theory and orbifold string theory and show that the known integrability in AdS/CFT extends to the general supersymmetric orbifolds of AdS5 x S5. There is an interesting interplay between the two descriptions of the orbifold gauge theory. Another interesting example is the Klebanov-Strassler (KS) background. We find the exhaustive list of the supergravity excitations in the I -odd sector of the KS theory. These comprise the three j = 1/2 massive supermultiplets each consisting of a (possibly pseudo) scalar, two fermions and a vector, and the two j = 1 supermultiplets whose bosonic content is a vector and a pseudovector. Surprisingly, the spectrum of the excitations which fit into the pure gauge sector strongly resembles the results obtained from the numeric studies in lattice gauge theory.

Universal fermionic spectral functions from string theory.

PubMed

Gauntlett, Jerome P; Sonner, Julian; Waldram, Daniel

2011-12-09

We carry out the first holographic calculation of a fermionic response function for a strongly coupled d=3 system with an explicit D=10 or D=11 supergravity dual. By considering the supersymmetry current, we obtain a universal result applicable to all d=3 N=2 SCFTs with such duals. Surprisingly, the spectral function does not exhibit a Fermi surface, despite the fact that the system is at finite charge density. We show that it has a phonino pole and at low frequencies there is a depletion of spectral weight with a power-law scaling which is governed by a locally quantum critical point.

AdS/CFT duality at strong coupling

NASA Astrophysics Data System (ADS)

Beccaria, M.; Ortix, C.

2007-08-01

We study the strong-coupling limit of the AdS/CFT correspondence in the framework of a recently proposed fermionic formulation of the Bethe ansatz equations governing the gauge theory anomalous dimensions. We give examples of states that do not follow the Gubser-Klebanov-Polyakov law at a large ’t Hooft coupling λ, in contrast to recent results on the quantum string Bethe equations that are valid in that regime. This result indicates that the fermionic construction cannot be trusted at large λ, although it remains an efficient tool for computing the weak-coupling expansion of anomalous dimensions.

Condition on Ramond-Ramond fluxes for factorization of worldsheet scattering in anti-de Sitter space

NASA Astrophysics Data System (ADS)

Wulff, Linus

2017-11-01

Factorization of scattering is the hallmark of integrable 1 +1 dimensional quantum field theories. For factorization of scattering to be possible the set of masses and momenta must be conserved in any two-to-two scattering process. We use this fact to constrain the form of the Ramond-Ramond fluxes for integrable supergravity anti-de Sitter (AdS) backgrounds by analyzing tree-level scattering of two AdS bosons into two fermions on the worldsheet of a Berenstein-Maldacena-Nastase string. We find a condition which can be efficiently used to rule out integrability of AdS strings and therefore of the corresponding AdS/conformal field theory dualities, as we demonstrate for some simple examples.

Second quantization in bit-string physics

NASA Technical Reports Server (NTRS)

Noyes, H. Pierre

1993-01-01

Using a new fundamental theory based on bit-strings, a finite and discrete version of the solutions of the free one particle Dirac equation as segmented trajectories with steps of length h/mc along the forward and backward light cones executed at velocity +/- c are derived. Interpreting the statistical fluctuations which cause the bends in these segmented trajectories as emission and absorption of radiation, these solutions are analogous to a fermion propagator in a second quantized theory. This allows us to interpret the mass parameter in the step length as the physical mass of the free particle. The radiation in interaction with it has the usual harmonic oscillator structure of a second quantized theory. How these free particle masses can be generated gravitationally using the combinatorial hierarchy sequence (3,10,137,2(sup 127) + 136), and some of the predictive consequences are sketched.

Hawking temperature of rotating charged black strings from tunneling

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

Ahmed, Jamil; Saifullah, K., E-mail: jamil_051@yahoo.com, E-mail: saifullah@qau.edu.pk

2011-11-01

Thermal radiations from spherically symmetric black holes have been studied from the point of view of quantum tunneling. In this paper we extend this approach to study radiation of fermions from charged and rotating black strings. Using WKB approximation and Hamilton-Jacobi method we work out the tunneling probabilities of incoming and outgoing fermions and find the correct Hawking temperature for these objects. We show that in appropriate limits the results reduce to those for the uncharged and non-rotating black strings.

Bosonization of nonrelativistic fermions on a circle: Tomonaga's problem revisited

NASA Astrophysics Data System (ADS)

Dhar, Avinash; Mandal, Gautam

2006-11-01

We use the recently developed tools for an exact bosonization of a finite number N of nonrelativistic fermions to discuss the classic Tomonaga problem. In the case of noninteracting fermions, the bosonized Hamiltonian naturally splits into an O(N) piece and an O(1) piece. We show that in the large-N and low-energy limit, the O(N) piece in the Hamiltonian describes a massless relativistic boson, while the O(1) piece gives rise to cubic self-interactions of the boson. At finite N and high energies, the low-energy effective description breaks down and the exact bosonized Hamiltonian must be used. We also comment on the connection between the Tomonaga problem and pure Yang-Mills theory on a cylinder. In the dual context of baby universes and multiple black holes in string theory, we point out that the O(N) piece in our bosonized Hamiltonian provides a simple understanding of the origin of two different kinds of nonperturbative O(e-N) corrections to the black hole partition function.

Living without supersymmetry—the conformal alternative and a dynamical Higgs boson

NASA Astrophysics Data System (ADS)

Mannheim, Philip D.

2017-11-01

We show that the key results of supersymmetry can be achieved via conformal symmetry instead. We propose that the Higgs boson be a dynamical fermion-antifermion bound state rather than an elementary scalar field, so that there is then no quadratically divergent self-energy problem for it and thus no need to invoke supersymmetry to resolve the problem. To obtain such a dynamical Higgs boson we study a conformal invariant gauge theory of interacting fermions and gauge bosons. The conformal invariance of the theory is realized via scaling with anomalous dimensions in the ultraviolet, and by a dynamical symmetry breaking via fermion bilinear condensates in the infrared, a breaking in which the dynamical dimension of the composite operator \\bar{\\psi }\\psi is reduced from three to two. With this reduction in dimension we can augment the gauge theory with a four-fermion interaction made renormalizable by this reduction, and can reinterpret the theory as a renormalizable version of the Nambu-Jona-Lasinio (NJL) model, with the gauge theory sector with its now massive fermion being a mean-field theory and the four-fermion interaction being the residual interaction. It is this residual interaction and not the mean field that then generates dynamical Goldstone and Higgs states, states that, as noted by Baker and Johnson, the gauge theory sector itself does not possess. The Higgs boson is found to be a narrow resonance just above threshold, with its width potentially being a diagnostic that could distinguish a dynamical Higgs boson from an elementary one. We couple the theory to a gravity theory, conformal gravity, that is equally conformal invariant, with the interplay between conformal gravity and the four-fermion interaction taking care of the vacuum energy problem. With conformal gravity being a unitary and renormalizable quantum theory of gravity there is no need for string theory with its supersymmetric underpinnings. With the vacuum energy problem being resolved and with conformal gravity fits to phenomena such as galactic rotation curves and the accelerating universe not needing dark matter, there is no need to introduce supersymmetry for either the vacuum energy problem or to provide a potential dark matter candidate. We propose that it is conformal symmetry rather than supersymmetry that is fundamental, with the theory of nature being a locally conformal, locally gauge invariant, non-Abelian NJL theory.

Nonlattice simulation for supersymmetric gauge theories in one dimension.

PubMed

Hanada, Masanori; Nishimura, Jun; Takeuchi, Shingo

2007-10-19

Lattice simulation of supersymmetric gauge theories is not straightforward. In some cases the lack of manifest supersymmetry just necessitates cumbersome fine-tuning, but in the worse cases the chiral and/or Majorana nature of fermions makes it difficult to even formulate an appropriate lattice theory. We propose circumventing all these problems inherent in the lattice approach by adopting a nonlattice approach for one-dimensional supersymmetric gauge theories, which are important in the string or M theory context. In particular, our method can be used to investigate the gauge-gravity duality from first principles, and to simulate M theory based on the matrix theory conjecture.

Discrete symmetries in the heterotic-string landscape

NASA Astrophysics Data System (ADS)

Athanasopoulos, P.

2015-07-01

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

Massless spinning particle and null-string on AdS d : projective-space approach

NASA Astrophysics Data System (ADS)

Uvarov, D. V.

2018-07-01

The massless spinning particle and the tensionless string models on an AdS d background in the projective-space realization are proposed as constrained Hamiltonian systems. Various forms of particle and string Lagrangians are derived and classical mechanics is studied including the Lax-type representation of the equations of motion. After that, the transition to the quantum theory is discussed. The analysis of potential anomalies in the tensionless string model necessitates the introduction of ghosts and BRST charge. It is shown that a quantum BRST charge is nilpotent for any d if coordinate-momentum ordering for the phase-space bosonic variables, Weyl ordering for the fermions and cb () ordering for the ghosts is chosen, while conformal reparametrizations and space-time dilatations turn out to be anomalous for ordering in terms of positive and negative Fourier modes of the phase-space variables and ghosts.

Conformal twists, Yang–Baxter σ-models & holographic noncommutativity

NASA Astrophysics Data System (ADS)

Araujo, Thiago; Bakhmatov, Ilya; Colgáin, Eoin Ó.; Sakamoto, Jun-ichi; Sheikh-Jabbari, Mohammad M.; Yoshida, Kentaroh

2018-06-01

Expanding upon earlier results (Araujo et al 2017 Phys. Rev. D 95 105006), we present a compendium of σ-models associated with integrable deformations of AdS5 generated by solutions to homogenous classical Yang–Baxter equation. Each example we study from four viewpoints: conformal (Drinfeld) twists, closed string gravity backgrounds, open string parameters and proposed dual noncommutative (NC) gauge theory. Irrespective of whether the deformed background is a solution to supergravity or generalized supergravity, we show that the open string metric associated with each gravity background is undeformed AdS5 with constant open string coupling and the NC structure Θ is directly related to the conformal twist. One novel feature is that Θ exhibits ‘holographic noncommutativity’: while it may exhibit non-trivial dependence on the holographic direction, its value everywhere in the bulk is uniquely determined by its value at the boundary, thus facilitating introduction of a dual NC gauge theory. We show that the divergence of the NC structure Θ is directly related to the unimodularity of the twist. We discuss the implementation of an outer automorphism of the conformal algebra as a coordinate transformation in the AdS bulk and discuss its implications for Yang–Baxter σ-models and self-T-duality based on fermionic T-duality. Finally, we comment on implications of our results for the integrability of associated open strings and planar integrability of dual NC gauge theories.

Modern Quantum Field Theory II - Proceeeings of the International Colloquium

NASA Astrophysics Data System (ADS)

Das, S. R.; Mandal, G.; Mukhi, S.; Wadia, S. R.

1995-08-01

The Table of Contents for the book is as follows: * Foreword * 1. Black Holes and Quantum Gravity * Quantum Black Holes and the Problem of Time * Black Hole Entropy and the Semiclassical Approximation * Entropy and Information Loss in Two Dimensions * Strings on a Cone and Black Hole Entropy (Abstract) * Boundary Dynamics, Black Holes and Spacetime Fluctuations in Dilation Gravity (Abstract) * Pair Creation of Black Holes (Abstract) * A Brief View of 2-Dim. String Theory and Black Holes (Abstract) * 2. String Theory * Non-Abelian Duality in WZW Models * Operators and Correlation Functions in c ≤ 1 String Theory * New Symmetries in String Theory * A Look at the Discretized Superstring Using Random Matrices * The Nested BRST Structure of Wn-Symmetries * Landau-Ginzburg Model for a Critical Topological String (Abstract) * On the Geometry of Wn Gravity (Abstract) * O(d, d) Tranformations, Marginal Deformations and the Coset Construction in WZNW Models (Abstract) * Nonperturbative Effects and Multicritical Behaviour of c = 1 Matrix Model (Abstract) * Singular Limits and String Solutions (Abstract) * BV Algebra on the Moduli Spaces of Riemann Surfaces and String Field Theory (Abstract) * 3. Condensed Matter and Statistical Mechanics * Stochastic Dynamics in a Deposition-Evaporation Model on a Line * Models with Inverse-Square Interactions: Conjectured Dynamical Correlation Functions of the Calogero-Sutherland Model at Rational Couplings * Turbulence and Generic Scale Invariance * Singular Perturbation Approach to Phase Ordering Dynamics * Kinetics of Diffusion-Controlled and Ballistically-Controlled Reactions * Field Theory of a Frustrated Heisenberg Spin Chain * FQHE Physics in Relativistic Field Theories * Importance of Initial Conditions in Determining the Dynamical Class of Cellular Automata (Abstract) * Do Hard-Core Bosons Exhibit Quantum Hall Effect? (Abstract) * Hysteresis in Ferromagnets * 4. Fundamental Aspects of Quantum Mechanics and Quantum Field Theory * Finite Quantum Physics and Noncommutative Geometry * Higgs as Gauge Field and the Standard Model * Canonical Quantisation of an Off-Conformal Theory * Deterministic Quantum Mechanics in One Dimension * Spin-Statistics Relations for Topological Geons in 2+1 Quantum Gravity * Generalized Fock Spaces * Geometrical Expression for Short Distance Singularities in Field Theory * 5. Mathematics and Quantum Field Theory * Knot Invariants from Quantum Field Theories * Infinite Grassmannians and Moduli Spaces of G-Bundles * A Review of an Algebraic Geometry Approach to a Model Quantum Field Theory on a Curve (Abstract) * 6. Integrable Models * Spectral Representation of Correlation Functions in Two-Dimensional Quantum Field Theories * On Various Avatars of the Pasquier Algebra * Supersymmetric Integrable Field Theories and Eight Vertex Free Fermion Models (Abstract) * 7. Lattice Field Theory * From Kondo Model and Strong Coupling Lattice QCD to the Isgur-Wise Function * Effective Confinement from a Logarithmically Running Coupling (Abstract)

Wilsonian dark matter in string derived Z' model

NASA Astrophysics Data System (ADS)

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

2017-09-01

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

Holographic non-Fermi-liquid fixed points.

PubMed

Faulkner, Tom; Iqbal, Nabil; Liu, Hong; McGreevy, John; Vegh, David

2011-04-28

Techniques arising from string theory can be used to study assemblies of strongly interacting fermions. Via this 'holographic duality', various strongly coupled many-body systems are solved using an auxiliary theory of gravity. Simple holographic realizations of finite density exhibit single-particle spectral functions with sharp Fermi surfaces, of a form distinct from those of the Landau theory. The self-energy is given by a correlation function in an infrared (IR) fixed-point theory that is represented by a two-dimensional anti de Sitter space (AdS(2)) region in the dual gravitational description. Here, we describe in detail the gravity calculation of this IR correlation function.

Tunneling topological vacua via extended operators: (Spin-)TQFT spectra and boundary deconfinement in various dimensions

NASA Astrophysics Data System (ADS)

Wang, Juven; Ohmori, Kantaro; Putrov, Pavel; Zheng, Yunqin; Wan, Zheyan; Guo, Meng; Lin, Hai; Gao, Peng; Yau, Shing-Tung

2018-05-01

Distinct quantum vacua of topologically ordered states can be tunneled into each other via extended operators. The possible applications include condensed matter and quantum cosmology. We present a straightforward approach to calculate the partition function on various manifolds and ground state degeneracy (GSD), mainly based on continuum/cochain topological quantum field theories (TQFTs), in any dimension. This information can be related to the counting of extended operators of bosonic/fermionic TQFTs. On the lattice scale, anyonic particles/strings live at the ends of line/surface operators. Certain systems in different dimensions are related to each other through dimensional reduction schemes, analogous to (de)categorification. Examples include spin TQFTs derived from gauging the interacting fermionic symmetry-protected topological states (with fermion parity {Z}_2^f) of symmetry groups {Z}_4× {Z}_2 and ({Z}_4)^2 in 3+1D, also {Z}_2 and ({Z}_2)^2 in 2+1D. Gauging the last three cases begets non-Abelian spin TQFTs (fermionic topological order). We consider situations where a TQFT lives on (1) a closed spacetime or (2) a spacetime with a boundary, such that the bulk and boundary are fully gapped and short- or long-range entangled (SRE/LRE). Anyonic excitations can be deconfined on the boundary. We introduce new exotic topological interfaces on which neither particle nor string excitations alone condense, but only fuzzy-composite objects of extended operators can end (e.g., a string-like composite object formed by a set of particles can end on a special 2+1D boundary of 3+1D bulk). We explore the relations between group extension constructions and partially breaking constructions (e.g., 0-form/higher-form/"composite" breaking) of topological boundaries, after gauging. We comment on the implications of entanglement entropy for some such LRE systems.

Free-fermion descriptions of parafermion chains and string-net models

NASA Astrophysics Data System (ADS)

Meichanetzidis, Konstantinos; Turner, Christopher J.; Farjami, Ashk; Papić, Zlatko; Pachos, Jiannis K.

2018-03-01

Topological phases of matter remain a focus of interest due to their unique properties: fractionalization, ground-state degeneracy, and exotic excitations. While some of these properties can occur in systems of free fermions, their emergence is generally associated with interactions between particles. Here, we quantify the role of interactions in general classes of topological states of matter in one and two spatial dimensions, including parafermion chains and string-net models. Surprisingly, we find that certain topological states can be exactly described by free fermions, while others saturate the maximum possible distance from their optimal free-fermion description [C. J. Turner et al., Nat. Commun. 8, 14926 (2017), 10.1038/ncomms14926]. Our work opens the door to understanding the complexity of topological models by establishing new types of fermionization procedures to describe their low-energy physics, thus making them amenable to experimental realizations.

New class of de Sitter vacua in string theory compactifications

NASA Astrophysics Data System (ADS)

Achúcarro, Ana; Ortiz, Pablo; Sousa, Kepa

2016-10-01

String theory contains few known working examples of de Sitter vacua, four-dimensional universes with a positive cosmological constant. A notorious obstacle is the stabilization of a large number—sometimes hundreds—of moduli fields that characterize the compact dimensions. We study the stability of a class of supersymmetric moduli (the complex structure moduli and dilaton in type-IIB flux compactifications) in the regime where the volume of the compact space is large but not exponentially large. We show that, if the number of moduli is very large, random matrix theory provides a new stability condition, a lower bound on the volume. We find a new class of stable vacua where the mass spectrum of these supersymmetric moduli is gapped, without requiring a large mass hierarchy between moduli sectors or any fine-tuning of the superpotential. We provide the first explicit example of this class of vacua in the P[1,1 ,1 ,6 ,9 ] 4 model. A distinguishing feature is that all fermions in the supersymmetric sector are lighter than the gravitino.

Emergent dimensions and branes from large-N confinement

NASA Astrophysics Data System (ADS)

Cherman, Aleksey; Poppitz, Erich

2016-12-01

N =1 S U (N ) super-Yang-Mills theory on R3×S1 is believed to have a smooth dependence on the circle size L . Making L small leads to calculable nonperturbative color confinement, mass gap, and string tensions. For finite N , the small-L low-energy dynamics is described by a three-dimensional effective theory. The large-N limit, however, reveals surprises: the infrared dual description is in terms of a theory with an emergent fourth dimension, curiously reminiscent of T-duality in string theory. Here, however, the emergent dimension is a lattice, with momenta related to the S1-winding of the gauge field holonomy, which takes values in ZN. Furthermore, the low-energy description is given by a nontrivial gapless theory, with a space-like z =2 Lifshitz scale invariance and operators that pick up anomalous dimensions as L is increased. Supersymmetry-breaking deformations leave the long-distance theory scale-invariant, but change the Lifshitz scaling exponent to z =1 , and lead to an emergent Lorentz symmetry at small L . Adding a small number of fundamental fermion fields leads to matter localized on three-dimensional branes in the emergent four-dimensional theory.

The Wonders of Supersymmetry: From Quantum Mechanics, Topology, and Noise, to (maybe) the LHC

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

Poppitz, Erich

2010-04-07

Supersymmetry, relating bosons and fermions was discovered almost 40 years ago in string theory and in quantum field theory, but the seeds of its 'miraculous' properties could have been seen already in quantum mechanics - which is also where it has found some of its more important applications. This talk introduces supersymmetry via the supersymmetric anharmonic oscillator. We shall see that this seemingly trivial example is sufficiently rich, allowing us to illustrate the uses of supersymmetric concepts in a variety of fields: mathematics, elementary particle physics, critical phenomena, and stochastic dynamics.

The Wonders of Supersymmetry: From Quantum Mechanics, Topology, and Noise, to (maybe) the LHC

ScienceCinema

Poppitz, Erich

2017-12-22

Supersymmetry, relating bosons and fermions was discovered almost 40 years ago in string theory and in quantum field theory, but the seeds of its 'miraculous' properties could have been seen already in quantum mechanics - which is also where it has found some of its more important applications. This talk introduces supersymmetry via the supersymmetric anharmonic oscillator. We shall see that this seemingly trivial example is sufficiently rich, allowing us to illustrate the uses of supersymmetric concepts in a variety of fields: mathematics, elementary particle physics, critical phenomena, and stochastic dynamics.

The Exploration of Hot Nuclear Matter

NASA Astrophysics Data System (ADS)

Jacak, Barbara V.; Müller, Berndt

2012-07-01

When nuclear matter is heated beyond 2 trillion degrees, it becomes a strongly coupled plasma of quarks and gluons. Experiments using highly energetic collisions between heavy nuclei have revealed that this new state of matter is a nearly ideal, highly opaque liquid. A description based on string theory and black holes in five dimensions has made the quark-gluon plasma an archetypical strongly coupled quantum system. Open questions about the structure and theory of the quark-gluon plasma are under active investigation. Many of the insights are also relevant to ultracold fermionic atoms and strongly correlated condensed matter.

Finite temperature corrections and embedded strings in noncommutative geometry and the standard model with neutrino mixing

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

Martins, R. A.

The recent extension of the standard model to include massive neutrinos in the framework of noncommutative geometry and the spectral action principle involves new scalar fields and their interactions with the usual complex scalar doublet. After ensuring that they bring no unphysical consequences, we address the question of how these fields affect the physics predicted in the Weinberg-Salam theory, particularly in the context of the electroweak phase transition. Applying the Dolan-Jackiw procedure, we calculate the finite temperature corrections, and find that the phase transition is first order. The new scalar interactions significantly improve the stability of the electroweak Z string,more » through the 'bag' phenomenon described by Vachaspati and Watkins ['Bound states can stabilize electroweak strings', Phys. Lett. B 318, 163-168 (1993)]. (Recently, cosmic strings have climbed back into interest due to a new evidence.) Sourced by static embedded strings, an internal space analogy of Cartan's torsion is drawn, and a possible Higgs-force-like 'gravitational' effect of this nonpropagating torsion on the fermion masses is described. We also check that the field generating the Majorana mass for the {nu}{sub R} is nonzero in the physical vacuum.« less

Periodic arrays of M2-branes

NASA Astrophysics Data System (ADS)

Jeon, Imtak; Lambert, Neil; Richmond, Paul

2012-11-01

We consider periodic arrays of M2-branes in the ABJM model in the spirit of a circle compactification to D2-branes in type IIA string theory. The result is a curious formulation of three-dimensional maximally supersymmetric Yang-Mills theory in terms of fermions, seven transverse scalars, a non-dynamical gauge field and an additional scalar `dual gluon'. Upon further T-duality on a transverse torus we obtain a non-manifest- Lorentz-invariant description of five-dimensional maximally supersymmetric Yang-Mills. Here the additional scalar field can be thought of as the components of a two-form along the torus. This action can be viewed as an M-theory description of M5-branes on {{{T}}^3}.

Charge modulation as fingerprints of phase-string triggered interference

NASA Astrophysics Data System (ADS)

Zhu, Zheng; Tian, Chushun; Jiang, Hong-Chen; Qi, Yang; Weng, Zheng-Yu; Zaanen, Jan

2015-07-01

Charge order appears to be an ubiquitous phenomenon in doped Mott insulators, which is currently under intense experimental and theoretical investigations particularly in the high Tc cuprates. This phenomenon is conventionally understood in terms of Hartree-Fock-type mean-field theory. Here we demonstrate a mechanism for charge modulation which is rooted in the many-particle quantum physics arising in the strong coupling limit. Specifically, we consider the problem of a single hole in a bipartite t -J ladder. As a remnant of the fermion signs, the hopping hole picks up subtle phases pending the fluctuating spins, the so-called phase-string effect. We demonstrate the presence of charge modulations in the density matrix renormalization group solutions which disappear when the phase strings are switched off. This form of charge modulation can be understood analytically in a path-integral language with a mean-field-like approximation adopted, showing that the phase strings give rise to constructive interferences leading to self-localization. When the latter occurs, left- and right-moving propagating modes emerge inside the localization volume and their interference is responsible for the real space charge modulation.

Emergence of gravity, fermion, gauge and Chern-Simons fields during formation of N-dimensional manifolds from joining point-like ones

NASA Astrophysics Data System (ADS)

Sepehri, Alireza; Shoorvazi, Somayyeh

In this paper, we will consider the birth and evolution of fields during formation of N-dimensional manifolds from joining point-like ones. We will show that at the beginning, only there are point-like manifolds which some strings are attached to them. By joining these manifolds, 1-dimensional manifolds are appeared and gravity, fermion, and gauge fields are emerged. By coupling these manifolds, higher dimensional manifolds are produced and higher orders of fermion, gauge fields and gravity are emerged. By decaying N-dimensional manifold, two child manifolds and a Chern-Simons one are born and anomaly is emerged. The Chern-Simons manifold connects two child manifolds and leads to the energy transmission from the bulk to manifolds and their expansion. We show that F-gravity can be emerged during the formation of N-dimensional manifold from point-like manifolds. This type of F-gravity includes both type of fermionic and bosonic gravity. G-fields and also C-fields which are produced by fermionic strings produce extra energy and change the gravity.

Virasoro algebra in the KN algebra; Bosonic string with fermionic ghosts on Riemann surfaces

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

Koibuchi, H.

1991-10-10

In this paper the bosonic string model with fermionic ghosts is considered in the framework of the KN algebra. The authors' attentions are paid to representations of KN algebra and a Clifford algebra of the ghosts. The authors show that a Virasoro-like algebra is obtained from KN algebra when KN algebra has certain antilinear anti-involution, and that it is isomorphic to the usual Virasoro algebra. The authors show that there is an expected relation between a central charge of this Virasoro-like algebra and an anomaly of the combined system.

Formation of Electron Strings in Narrow Band Polar Semiconductors

NASA Astrophysics Data System (ADS)

Kusmartsev, F. V.

2000-01-01

We show that linear electron strings may arise in polar semiconductors. A single string consists of M spinless fermions trapped by an extended polarization well of a cigar shape. Inside the string the particles are free although they interact with each other via Coulomb forces. The strings arise as a result of an electronic phase separation associated with an instability of small adiabatic polarons. We have found the length of the string which depends on dielectric constants of semiconductors. The appearance of these electron strings may have an impact on the effect of stripe formation observed in a variety of high- Tc experiments.

d-Brane Instantons in Type II Orientifolds

NASA Astrophysics Data System (ADS)

Blumenhagen, Ralph; Cvetič, Mirjam; Kachru, Shamit; Weigand, Timo

2009-11-01

We review recent progress in determining the effects of d-brane instantons in [Formula: see text] supersymmetric compactifications of Type II string theory to four dimensions. We describe the abstract d-brane instanton calculus for holomorphic couplings such as the superpotential, the gauge kinetic function, and higher fermionic F-terms, and we briefly discuss the implications of background fluxes for the instanton sector. We then summarize the concrete consequences of stringy d-brane instantons for the construction of semirealistic models of particle physics or supersymmetry breaking in compact and noncompact geometries.

Fermionic vacuum polarization by an Abelian magnetic tube in the cosmic string spacetime

NASA Astrophysics Data System (ADS)

Maior de Sousa, M. S.; Ribeiro, R. F.; Bezerra de Mello, E. R.

2017-02-01

In this paper, we consider a charged massive fermionic quantum field in the idealized cosmic string spacetime and in the presence of a magnetic field confined in a cylindrical tube of finite radius. Three distinct configurations for the magnetic fields are taken into account: (i) a cylindrical shell of radius a , (ii) a magnetic field proportional to 1 /r , and (iii) a constant magnetic field. In these three cases, the axis of the infinitely long tube of radius a coincides with the cosmic string. Our main objectives in this paper are to analyze the fermionic condensate (FC) and the vacuum expectation value (VEV) of the fermionic energy-momentum tensor. In order to do that, we explicitly construct the complete set of normalized wave functions for each configuration of the magnetic field. We show that in the region outside the tube, the FC and the VEV of the energy-momentum tensor are decomposed into two parts: The first ones correspond to the zero-thickness magnetic flux contributions, and the second ones are induced by the nontrivial structure of the magnetic field, named core-induced contributions. The latter present specific forms depending on the magnetic field configuration considered. We also show that the VEV of the energy-momentum tensor is diagonal and obeys the conservation condition, and its trace is expressed in terms of the fermionic condensate. The zero-thickness contributions to the FC and VEV of the energy-momentum tensor depend only on the fractional part of the ration of the magnetic flux inside the tube by the quantum one. As to the core-induced contributions, they depend on the total magnetic flux inside the tube and, consequently, in general, are not a periodic function of the magnetic flux.

Hawking Radiation of Massive Bosons via Tunneling from Black Strings

NASA Astrophysics Data System (ADS)

Feng, Zhong-Wen

2017-12-01

In the present paper, the Hawking radiation of massive bosons from 4-dimensional and 5-dimensional black strings are studied in quantum tunneling formalism. First, we derive the Hamilton-Jacobi equation set via the Proca equation and WKB approximation. Then, the tunneling rates and Hawking temperatures of the black strings are obtained. Our calculations show that the tunneling rates and Hawking temperatures are related to the properties of black strings' spacetime. When compare our results with those of scalars and fermions cases, it finds that they are the same.

Hawking Radiation of Massive Bosons via Tunneling from Black Strings

NASA Astrophysics Data System (ADS)

Feng, Zhong-Wen

2018-03-01

In the present paper, the Hawking radiation of massive bosons from 4-dimensional and 5-dimensional black strings are studied in quantum tunneling formalism. First, we derive the Hamilton-Jacobi equation set via the Proca equation and WKB approximation. Then, the tunneling rates and Hawking temperatures of the black strings are obtained. Our calculations show that the tunneling rates and Hawking temperatures are related to the properties of black strings' spacetime. When compare our results with those of scalars and fermions cases, it finds that they are the same.

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

Zhu, Zheng; Tian, Chushun; Jiang, Hong-Chen

Charge order appears to be an ubiquitous phenomenon in doped Mott insulators, which is currently under intense experimental and theoretical investigations particularly in the high T c cuprates. This phenomenon is conventionally understood in terms of Hartree-Fock-type mean-field theory. Here we demonstrate a mechanism for charge modulation which is rooted in the many-particle quantum physics arising in the strong coupling limit. Specifically, we consider the problem of a single hole in a bipartite t - J ladder. As a remnant of the fermion signs, the hopping hole picks up subtle phases pending the fluctuating spins, the so-called phase-string effect. Wemore » demonstrate the presence of charge modulations in the density matrix renormalization group solutions which disappear when the phase strings are switched off. This form of charge modulation can be understood analytically in a path-integral language with a mean-field-like approximation adopted, showing that the phase strings give rise to constructive interferences leading to self-localization. When the latter occurs, left- and right-moving propagating modes emerge inside the localization volume and their interference is responsible for the real space charge modulation.« less

Initial Systematic Investigations of the Weakly Coupled Free Fermionic Heterotic String Landscape Statistics

NASA Astrophysics Data System (ADS)

Renner, Timothy

2011-12-01

A C++ framework was constructed with the explicit purpose of systematically generating string models using the Weakly Coupled Free Fermionic Heterotic String (WCFFHS) method. The software, optimized for speed, generality, and ease of use, has been used to conduct preliminary systematic investigations of WCFFHS vacua. Documentation for this framework is provided in the Appendix. After an introduction to theoretical and computational aspects of WCFFHS model building, a study of ten-dimensional WCFFHS models is presented. Degeneracies among equivalent expressions of each of the known models are investigated and classified. A study of more phenomenologically realistic four-dimensional models based on the well known "NAHE" set is then presented, with statistics being reported on gauge content, matter representations, and space-time supersymmetries. The final study is a parallel to the NAHE study in which a variation of the NAHE set is systematically extended and examined statistically. Special attention is paid to models with "mirroring"---identical observable and hidden sector gauge groups and matter representations.

Cosmic strings and baryon decay catalysis

NASA Technical Reports Server (NTRS)

Gregory, Ruth; Perkins, W. B.; Davis, A.-C.; Brandenberger, R. H.

1989-01-01

Cosmic strings, like monopoles, can catalyze proton decay. For integer charged fermions, the cross section for catalysis is not amplified, unlike in the case of monopoles. The catalysis processes are reviewed both in the free quark and skyrmion pictures and the implications for baryogenesis are discussed. A computation of the cross section for monopole catalyzed skyrmion decay is presented using classical physics. Also discussed are some effects which can screen catalysis processes.

Exactly soluble local bosonic cocycle models, statistical transmutation, and simplest time-reversal symmetric topological orders in 3+1 dimensions

NASA Astrophysics Data System (ADS)

Wen, Xiao-Gang

2017-05-01

We propose a generic construction of exactly soluble local bosonic models that realize various topological orders with gappable boundaries. In particular, we construct an exactly soluble bosonic model that realizes a (3+1)-dimensional [(3+1)D] Z2-gauge theory with emergent fermionic Kramers doublet. We show that the emergence of such a fermion will cause the nucleation of certain topological excitations in space-time without pin+ structure. The exactly soluble model also leads to a statistical transmutation in (3+1)D. In addition, we construct exactly soluble bosonic models that realize 2 types of time-reversal symmetry-enriched Z2 topological orders in 2+1 dimensions, and 20 types of simplest time-reversal symmetry-enriched topological (SET) orders which have only one nontrivial pointlike and stringlike topological excitation. Many physical properties of those topological states are calculated using the exactly soluble models. We find that some time-reversal SET orders have pointlike excitations that carry Kramers doublet, a fractionalized time-reversal symmetry. We also find that some Z2 SET orders have stringlike excitations that carry anomalous (nononsite) Z2 symmetry, which can be viewed as a fractionalization of Z2 symmetry on strings. Our construction is based on cochains and cocycles in algebraic topology, which is very versatile. In principle, it can also realize emergent topological field theory beyond the twisted gauge theory.

Gravitational Scattering Amplitudes and Closed String Field Theory in the Proper-Time Gauge

NASA Astrophysics Data System (ADS)

Lee, Taejin

2018-01-01

We construct a covariant closed string field theory by extending recent works on the covariant open string field theory in the proper-time gauge. Rewriting the string scattering amplitudes generated by the closed string field theory in terms of the Polyakov string path integrals, we identify the Fock space representations of the closed string vertices. We show that the Fock space representations of the closed string field theory may be completely factorized into those of the open string field theory. It implies that the well known Kawai-Lewellen-Tye (KLT) relations of the first quantized string theory may be promoted to the second quantized closed string theory. We explicitly calculate the scattering amplitudes of three gravitons by using the closed string field theory in the proper-time gauge.

Physical and geometrical aspects of de sitter interior of a gravastar

NASA Astrophysics Data System (ADS)

Morawiec, Pawel Jan

The principal motivation for the investigations reported in this thesis is the gravastar model for physical black holes. According to this model the final state of the gravitational collapse of cold super-dense stars with the mass greater than some critical value is a non-singular object called a gravastar. This thesis presents results related to the various aspects of the de Sitter interior of a gravastar. The main object of the research was a generalized rotating interior of a gravastar. It was shown that the rotation, characterized by the vorticity, is localized on the vortex line. The metric under considerations is the de Sitter metric, however in some variant of the oblate spheroidal coordinates. Additionally a cosmic string on the rotation axis is present. This new result is the de Sitter version of the Mazur string, which was obtained from the four dimensional Levi-Civita metric as the generalization of the three-dimensional cosmic string by Adler and Jackiw. Also, using analogy between rotation in the superfluid and the magnetic field we gave another example of the Cosmic No Hair Theorem, this time "no magnetic fields in de Sitter space". But we also have shown that when the de Sitter event horizon is replaced by a thin shell (with a finite thickness), as it is in the gravastar model, the non-vanishing magnetic field could be present. To our knowledge these are new results. In this thesis we have studied behavior of the massless Dirac field as an example of a matter field in the de Sitter spacetime in the vicinity of an event horizon. We found convenient to work in the frame of the optical geometry of the de Sitter space as it is related to the metric in the static coordinates through a conformal Weyl rescaling and the dynamics of the massless Dirac fields is conformally invariant. The fact that the spatial part of the metric in the optical geometry of de Sitter space is the constant negative curvature Lobachevski space (the Euclidean ant-de Sitter space) suggested the existenc of the emerging de Sitter quantum field theory and conformal field theory correspondence on the de Sitter event horizon. We have studied implications of this conjecture. According to the AdS/CFT correspondence prescription the functional integral over the matter fields described by the action with the properly chosen boundary terms defining the so called partition function as the functional of the boundary values of the matter fields is also the generating functional for the correlation functions in the conformal field theory on the boundary of AdS space. In the case of the optical geometry of the de Sitter space the boundary is the event horizon that is the boundary of its Lobachevski spatial part times time. We have chosen the action for the massless Dirac fields in the optical de Sitter geometry with appropriate surface term and subsequently we have evaluated the real time partition function as the functional of the carefully defined boundary values of the Dirac field. It turns out that this partition functional can be, indeed, interpreted as the generating functional of the real time conformal field theory correlation functions of the fermionic operators, dual to the fermionic fields on the boundary. This means that the conformal field theory correlation functions are evaluated as the vacuum expectation values of the chronologically ordered fermionic operator. This result demonstrates the emergence of the de Sitter/Conformal field theory correspondence on the de Sitter horizon. The presence of the negative curvature Lobachevski geometry in the spatial part of the optical geometry of the de Sitter space, is responsible for the effective one-dimensional behavior of the matter degrees of freedom and of the emergence of the de Sitter/Conformal field theory correspondence on the event horizon. Although we have demonstrated the existence of this correspondence for the fermionic fields only, we anticipate this result to be valid generally.

Covariant open bosonic string field theory on multiple D-branes in the proper-time gauge

NASA Astrophysics Data System (ADS)

Lee, Taejin

2017-12-01

We construct a covariant open bosonic string field theory on multiple D-branes, which reduces to a non-Abelian group Yang-Mills gauge theory in the zero-slope limit. Making use of the first quantized open bosonic string in the proper time gauge, we convert the string amplitudes given by the Polyakov path integrals on string world sheets into those of the second quantized theory. The world sheet diagrams generated by the constructed open string field theory are planar in contrast to those of the Witten's cubic string field theory. However, the constructed string field theory is yet equivalent to the Witten's cubic string field theory. Having obtained planar diagrams, we may adopt the light-cone string field theory technique to calculate the multi-string scattering amplitudes with an arbitrary number of external strings. We examine in detail the three-string vertex diagram and the effective four-string vertex diagrams generated perturbatively by the three-string vertex at tree level. In the zero-slope limit, the string scattering amplitudes are identified precisely as those of non-Abelian Yang-Mills gauge theory if the external states are chosen to be massless vector particles.

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

Bhardwaj, Lakshya; Gaiotto, Davide; Kapustin, Anton

It is possible to describe fermionic phases of matter and spin-topological field theories in 2+1d in terms of bosonic “shadow” theories, which are obtained from the original theory by “gauging fermionic parity”. Furthemore, the fermionic/spin theories are recovered from their shadow by a process of fermionic anyon condensation: gauging a one-form symmetry generated by quasi-particles with fermionic statistics. We apply the formalism to theories which admit gapped boundary conditions. We obtain Turaev-Viro-like and Levin-Wen-like constructions of fermionic phases of matter. Here, we describe the group structure of fermionic SPT phases protected by Z 2f × G. The quaternion group makesmore » a surprise appearance.« less

Complete spectrum of long operators in Script N = 4 SYM at one loop

NASA Astrophysics Data System (ADS)

Beisert, Niklas; Kazakov, Vladimir A.; Sakai, Kazuhiro; Zarembo, Konstantin

2005-07-01

We construct the complete spectral curve for an arbitrary local operator, including fermions and covariant derivatives, of one-loop Script N = 4 gauge theory in the thermodynamic limit. This curve perfectly reproduces the Frolov-Tseytlin limit of the full spectral curve of classical strings on AdS5 × S5 derived in [64]. To complete the comparison we introduce stacks, novel bound states of roots of different flavors which arise in the thermodynamic limit of the corresponding Bethe ansatz equations. We furthermore show the equivalence of various types of Bethe equations for the underlying fraktur sfraktur u(2,2|4) superalgebra, in particular of the type ``Beauty'' and ``Beast''.

Aspects of some dualities in string theory

NASA Astrophysics Data System (ADS)

Kim, Bom Soo

AdS/CFT correspondence in string theory has changed landscape of the theoretical physics. Through this celebrated duality between gravity theory and field theory, one can investigate analytically strongly coupled gauge theories such as Quantum Chromodynamics (QCD) in terms of weakly coupled string theory such as supergravity theory and vice versa. In the first part of this thesis we used this duality to construct a new type of nonlocal field theory, called Puff Field Theory, in terms of D3 branes in type IIB string theory with a geometric twist. In addition to the strong-weak duality of AdS/CFT, there also exists a weak-weak duality, called Twistor String Theory. Twistor technique is successfully used to calculate the SYM scattering amplitude in an elegant fashion. Yet, the progress in the string theory side was hindered by a non-unitary conformal gravity. We extend the Twistor string theory by introducing mass terms, in the second part of the thesis. A chiral mass term is identified as a vacuum expectation value of a conformal supergravity field and is tied with the breaking of the conformal symmetry of gravity. As a prime candidate for a quantum theory of gravity, string theory revealed many promising successes such as counting the number of microstates in supersymmetric Black Holes thermodynamics and resolution of timelike and null singularities, to name a few. Yet, the fundamental string and M-theroy formulations are not yet available. Various string theories without gravity, such as Non-Commutative Open String (NCOS) and Open Membrane (OM) theories, are very nice playground to investigate the fundamental structure of string and M-theory without the complication of gravity. In the last part of the thesis, simpler Non-Relativistic String Theories are constructed and investigated. One important motivation for those theories is related to the connection between Non-Relativistic String Theories and Non-critical String Theories through the bosonization of betagamma CFT.

Charting the landscape of supercritical string theory.

PubMed

Hellerman, Simeon; Swanson, Ian

2007-10-26

Special solutions of string theory in supercritical dimensions can interpolate in time between theories with different numbers of spacetime dimensions and different amounts of world sheet supersymmetry. These solutions connect supercritical string theories to the more familiar string duality web in ten dimensions and provide a precise link between supersymmetric and purely bosonic string theories. Dimension quenching and c duality appear to be natural concepts in string theory, giving rise to large networks of interconnected theories.

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

Dijkgraaf, Robbert; Gopakumar, Rajesh; Ooguri, Hirosi

We argue that the holographic description of four-dimensional Bogomol'nyi-Prasad-Sommerfield black holes naturally includes multicenter solutions. This suggests that the holographic dual to the gauge theory is not a single AdS{sub 2}xS{sup 2} but a coherent ensemble of them. We verify this in a particular class of examples, where the two-dimensional Yang-Mills theory gives a holographic description of the black holes obtained by branes wrapping Calabi-Yau cycles. Using the free fermionic formulation, we show that O(e{sup -N}) nonperturbative effects entangle the two Fermi surfaces. In an Euclidean description, the wave function of the multicenter black holes gets mapped to the Hartle-Hawkingmore » wave function of baby universes. This provides a concrete realization, within string theory, of effects that can be interpreted as the creation of baby universes. We find that, at least in the case we study, the baby universes do not lead to a loss of quantum coherence, in accord with general arguments.« less

String scattering amplitudes and deformed cubic string field theory

NASA Astrophysics Data System (ADS)

Lai, Sheng-Hong; Lee, Jen-Chi; Lee, Taejin; Yang, Yi

2018-01-01

We study string scattering amplitudes by using the deformed cubic string field theory which is equivalent to the string field theory in the proper-time gauge. The four-string scattering amplitudes with three tachyons and an arbitrary string state are calculated. The string field theory yields the string scattering amplitudes evaluated on the world sheet of string scattering whereas the conventional method, based on the first quantized theory brings us the string scattering amplitudes defined on the upper half plane. For the highest spin states, generated by the primary operators, both calculations are in perfect agreement. In this case, the string scattering amplitudes are invariant under the conformal transformation, which maps the string world sheet onto the upper half plane. If the external string states are general massive states, generated by non-primary field operators, we need to take into account carefully the conformal transformation between the world sheet and the upper half plane. We show by an explicit calculation that the string scattering amplitudes calculated by using the deformed cubic string field theory transform into those of the first quantized theory on the upper half plane by the conformal transformation, generated by the Schwarz-Christoffel mapping.

E(lementary)-strings in six-dimensional heterotic F-theory

NASA Astrophysics Data System (ADS)

Choi, Kang-Sin; Rey, Soo-Jong

2017-09-01

Using E-strings, we can analyze not only six-dimensional superconformal field theories but also probe vacua of non-perturabative heterotic string. We study strings made of D3-branes wrapped on various two-cycles in the global F-theory setup. We claim that E-strings are elementary in the sense that various combinations of E-strings can form M-strings as well as heterotic strings and new kind of strings, called G-strings. Using them, we show that emissions and combinations of heterotic small instantons generate most of known six-dimensional superconformal theories, their affinizations and little string theories. Taking account of global structure of compact internal geometry, we also show that special combinations of E-strings play an important role in constructing six-dimensional theories of D- and E-types. We check global consistency conditions from anomaly cancellation conditions, both from five-branes and strings, and show that they are given in terms of elementary E-string combinations.

Top-quark mass coupling and classification of weakly coupled heterotic superstring vacua

NASA Astrophysics Data System (ADS)

Rizos, J.

2014-06-01

The quest for the Standard Model among the huge number of string vacua is usually based on a set of phenomenological criteria related to the massless spectrum of string models. In this work we study criteria associated with interactions in the effective low energy theory and in particular with the presence of the coupling that provides mass to the top quark. Working in the context of the free-fermionic formulation of the heterotic superstring, we demonstrate that, in a big class of phenomenologically promising compactifications, these criteria can be expressed entirely in terms of the generalised GSO projection coefficients entering the definition of the models. They are shown to be very efficient in identifying phenomenologically viable vacua, especially in the framework of computer-based search, as they are met by approximately one every models. We apply our results in the investigation of a class of supersymmetric Pati-Salam vacua, comprising configurations, and we show that when combined with other phenomenological requirements they lead to a relatively small set of about Standard Model compatible models that can be fully classified.

Perturbative quantum field theory in the framework of the fermionic projector

NASA Astrophysics Data System (ADS)

Finster, Felix

2014-04-01

We give a microscopic derivation of perturbative quantum field theory, taking causal fermion systems and the framework of the fermionic projector as the starting point. The resulting quantum field theory agrees with standard quantum field theory on the tree level and reproduces all bosonic loop diagrams. The fermion loops are described in a different formalism in which no ultraviolet divergences occur.

Fast proton decay

NASA Astrophysics Data System (ADS)

Li, Tianjun; Nanopoulos, Dimitri V.; Walker, Joel W.

2010-10-01

We consider proton decay in the testable flipped SU(5)×U(1)X models with TeV-scale vector-like particles which can be realized in free fermionic string constructions and F-theory model building. We significantly improve upon the determination of light threshold effects from prior studies, and perform a fresh calculation of the second loop for the process p→eπ from the heavy gauge boson exchange. The cumulative result is comparatively fast proton decay, with a majority of the most plausible parameter space within reach of the future Hyper-Kamiokande and DUSEL experiments. Because the TeV-scale vector-like particles can be produced at the LHC, we predict a strong correlation between the most exciting particle physics experiments of the coming decade.

Hidden magnetism in periodically modulated one dimensional dipolar fermions

NASA Astrophysics Data System (ADS)

Fazzini, S.; Montorsi, A.; Roncaglia, M.; Barbiero, L.

2017-12-01

The experimental realization of time-dependent ultracold lattice systems has paved the way towards the implementation of new Hubbard-like Hamiltonians. We show that in a one-dimensional two-components lattice dipolar Fermi gas the competition between long range repulsion and correlated hopping induced by periodically modulated on-site interaction allows for the formation of hidden magnetic phases, with degenerate protected edge modes. The magnetism, characterized solely by string-like nonlocal order parameters, manifests in the charge and/or in the spin degrees of freedom. Such behavior is enlighten by employing Luttinger liquid theory and numerical methods. The range of parameters for which hidden magnetism is present can be reached by means of the currently available experimental setups and probes.

The WZNW model on PSU(1,1|2)

NASA Astrophysics Data System (ADS)

Götz, Gerhard; Quella, Thomas; Schomerus, Volker

2007-03-01

According to the work of Berkovits, Vafa and Witten, the non-linear sigma model on the supergroup PSU(1,1|2) is the essential building block for string theory on AdS3 × S3 × T4. Models associated with a non-vanishing value of the RR flux can be obtained through a psu(1,1|2) invariant marginal deformation of the WZNW model on PSU(1,1|2). We take this as a motivation to present a manifestly psu(1,1|2) covariant construction of the model at the Wess-Zumino point, corresponding to a purely NSNS background 3-form flux. At this point the model possesses an enhanced psu with wide hat(1,1|2) current algebra symmetry whose representation theory, including explicit character formulas, is developed systematically in the first part of the paper. The space of vertex operators and a free fermion representation for their correlation functions is our main subject in the second part. Contrary to a widespread claim, bosonic and fermionic fields are necessarily coupled to each other. The interaction changes the supersymmetry transformations, with drastic consequences for the multiplets of localized normalizable states in the model. It is only this fact which allows us to decompose the full state space into multiplets of the global supersymmetry. We analyze these decompositions systematically as a preparation for a forthcoming study of the RR deformation.

Remarks on entanglement entropy in string theory

NASA Astrophysics Data System (ADS)

Balasubramanian, Vijay; Parrikar, Onkar

2018-03-01

Entanglement entropy for spatial subregions is difficult to define in string theory because of the extended nature of strings. Here we propose a definition for bosonic open strings using the framework of string field theory. The key difference (compared to ordinary quantum field theory) is that the subregion is chosen inside a Cauchy surface in the "space of open string configurations." We first present a simple calculation of this entanglement entropy in free light-cone string field theory, ignoring subtleties related to the factorization of the Hilbert space. We reproduce the answer expected from an effective field theory point of view, namely a sum over the one-loop entanglement entropies corresponding to all the particle-excitations of the string, and further show that the full string theory regulates ultraviolet divergences in the entanglement entropy. We then revisit the question of factorization of the Hilbert space by analyzing the covariant phase-space associated with a subregion in Witten's covariant string field theory. We show that the pure gauge (i.e., BRST exact) modes in the string field become dynamical at the entanglement cut. Thus, a proper definition of the entropy must involve an extended Hilbert space, with new stringy edge modes localized at the entanglement cut.

Noncommutative Field Theories and (super)string Field Theories

NASA Astrophysics Data System (ADS)

Aref'eva, I. Ya.; Belov, D. M.; Giryavets, A. A.; Koshelev, A. S.; Medvedev, P. B.

2002-11-01

In this lecture notes we explain and discuss some ideas concerning noncommutative geometry in general, as well as noncommutative field theories and string field theories. We consider noncommutative quantum field theories emphasizing an issue of their renormalizability and the UV/IR mixing. Sen's conjectures on open string tachyon condensation and their application to the D-brane physics have led to wide investigations of the covariant string field theory proposed by Witten about 15 years ago. We review main ingredients of cubic (super)string field theories using various formulations: functional, operator, conformal and the half string formalisms. The main technical tools that are used to study conjectured D-brane decay into closed string vacuum through the tachyon condensation are presented. We describe also methods which are used to study the cubic open string field theory around the tachyon vacuum: construction of the sliver state, "comma" and matrix representations of vertices.

Fluctuations of a q-deformed fermion gas

NASA Astrophysics Data System (ADS)

Zeng, Qijun; Ge, Jing; Luo, Yongsong

2018-05-01

The theory of q-deformed fermions is one of the theories of q-deformed oscillators. Within the framework of this theory and the traditional fluctuation theory, we investigate fluctuations of q-deformed fermion gas and obtain the expressions of fluctuations of the internal energy U, the particle number N and the correlation of fluctuations of the two physical quantities above. Further numerical calculation reveals that fluctuations of such a system have some interesting and particular features. We consider that this work may provide much insight into the theory of q fermions, and may also be helpful for the theory of q-deformed oscillators.

G-theory: The generator of M-theory and supersymmetry

NASA Astrophysics Data System (ADS)

Sepehri, Alireza; Pincak, Richard

2018-04-01

In string theory with ten dimensions, all Dp-branes are constructed from D0-branes whose action has two-dimensional brackets of Lie 2-algebra. Also, in M-theory, with 11 dimensions, all Mp-branes are built from M0-branes whose action contains three-dimensional brackets of Lie 3-algebra. In these theories, the reason for difference between bosons and fermions is unclear and especially in M-theory there is not any stable object like stable M3-branes on which our universe would be formed on it and for this reason it cannot help us to explain cosmological events. For this reason, we construct G-theory with M dimensions whose branes are formed from G0-branes with N-dimensional brackets. In this theory, we assume that at the beginning there is nothing. Then, two energies, which differ in their signs only, emerge and produce 2M degrees of freedom. Each two degrees of freedom create a new dimension and then M dimensions emerge. M-N of these degrees of freedom are removed by symmetrically compacting half of M-N dimensions to produce Lie-N-algebra. In fact, each dimension produces a degree of freedom. Consequently, by compacting M-N dimensions from M dimensions, N dimensions and N degrees of freedom is emerged. These N degrees of freedoms produce Lie-N-algebra. During this compactification, some dimensions take extra i and are different from other dimensions, which are known as time coordinates. By this compactification, two types of branes, Gp and anti-Gp-branes, are produced and rank of tensor fields which live on them changes from zero to dimension of brane. The number of time coordinates, which are produced by negative energy in anti-Gp-branes, is more sensible to number of times in Gp-branes. These branes are compactified anti-symmetrically and then fermionic superpartners of bosonic fields emerge and supersymmetry is born. Some of gauge fields play the role of graviton and gravitino and produce the supergravity. The question may arise that what is the physical reason which shows that this theory is true. We shown that G-theory can be reduced to other theories like nonlinear gravity theories in four dimensions. Also, this theory, can explain the physical properties of fermions and bosons. On the other hand, this theory explains the origin of supersymmetry. For this reason, we can prove that this theory is true. By reducing the dimension of algebra to three and dimension of world to 11 and dimension of brane to four, G-theory is reduced to F(R)-gravity.

Bosonization of fermions coupled to topologically massive gravity

NASA Astrophysics Data System (ADS)

Fradkin, Eduardo; Moreno, Enrique F.; Schaposnik, Fidel A.

2014-03-01

We establish a duality between massive fermions coupled to topologically massive gravity (TMG) in d=3 space-time dimensions and a purely gravity theory which also will turn out to be a TMG theory but with different parameters: the original graviton mass in the TMG theory coupled to fermions picks up a contribution from fermion bosonization. We obtain explicit bosonization rules for the fermionic currents and for the energy-momentum tensor showing that the identifications do not depend explicitly on the parameters of the theory. These results are the gravitational analog of the results for 2+1 Abelian and non-Abelian bosonization in flat space-time.

Flavor condensates in brane models and dark energy

NASA Astrophysics Data System (ADS)

Mavromatos, Nick E.; Sarkar, Sarben; Tarantino, Walter

2009-10-01

In the context of a microscopic model of string-inspired foam, in which foamy structures are provided by brany pointlike defects (D-particles) in space-time, we discuss flavor mixing as a result of flavor nonpreserving interactions of (low-energy) fermionic stringy matter excitations with the defects. Such interactions involve splitting and capture of the matter string state by the defect, and subsequent re-emission. As a result of charge conservation, only electrically neutral matter can interact with the D-particles. Quantum fluctuations of the D-particles induce a nontrivial space-time background; in some circumstances, this could be akin to a cosmological Friedman-Robertson-Walker expanding-universe, with weak (but nonzero) particle production. Furthermore, the D-particle medium can induce an Mikheyev-Smirnov-Wolfenstein-type effect. We have argued previously, in the context of bosons, that the so-called flavor vacuum is the appropriate state to be used, at least for low-energy excitations, with energies/momenta up to a dynamically determined cutoff scale. Given the intriguing mass scale provided by neutrino flavor mass differences from the point of view of dark energy, we evaluate the flavor-vacuum expectation value (condensate) of the stress-energy tensor of the 1/2-spin fields with mixing in an effective-low-energy quantum field theory in this foam-induced curved space-time. We demonstrate, at late epochs of the Universe, that the fermionic vacuum condensate behaves as a fluid with negative pressure and positive energy; however, the equation of state has wfermion>-1/3 and so the contribution of the fermion-fluid flavor vacuum alone could not yield accelerating universes. Such contributions to the vacuum energy should be considered as (algebraically) additive to the flavored boson contributions, evaluated in our previous works; this should be considered as natural from (broken) target-space supersymmetry that characterizes realistic superstring/supermembrane models of space-time foam. The boson fluid is also characterized by positive energy and negative pressure, but its equation of state is, for late eras, close to wboson→-1, and hence overall the D-foam universe appears accelerating at late eras.

Further Development of HS Field Theory

NASA Astrophysics Data System (ADS)

Abdurrahman, Abdulmajeed; Faridani, Jacqueline; Gassem, Mahmoud

2006-04-01

We present a systematic treatment of the HS Field theory of the open bosonic string and discuss its relationship to other full string field theories of the open bosonic string such as Witten's theory and the CVS theory. In the development of the HS field theory we encounter infinite dimensional matrices arising from the change of representation between the two theories, i.e., the HS field theory and the full string field theory. We give a general procedure of how to invert these gigantic matrices. The inversion of these matrices involves the computation of many infinite sums. We give the values of these sums and state their generalizations arising from considering higher order vertices (i.e., more than three strings) in string field theory. Moreover, we give a general procedure, on how to evaluate the generalized sums, that can be extended to many generic sums of similar properties. We also discuss the conformal operator connecting the HS field theory to that of the CVS string field theory.

Minimal string theories and integrable hierarchies

NASA Astrophysics Data System (ADS)

Iyer, Ramakrishnan

Well-defined, non-perturbative formulations of the physics of string theories in specific minimal or superminimal model backgrounds can be obtained by solving matrix models in the double scaling limit. They provide us with the first examples of completely solvable string theories. Despite being relatively simple compared to higher dimensional critical string theories, they furnish non-perturbative descriptions of interesting physical phenomena such as geometrical transitions between D-branes and fluxes, tachyon condensation and holography. The physics of these theories in the minimal model backgrounds is succinctly encoded in a non-linear differential equation known as the string equation, along with an associated hierarchy of integrable partial differential equations (PDEs). The bosonic string in (2,2m-1) conformal minimal model backgrounds and the type 0A string in (2,4 m) superconformal minimal model backgrounds have the Korteweg-de Vries system, while type 0B in (2,4m) backgrounds has the Zakharov-Shabat system. The integrable PDE hierarchy governs flows between backgrounds with different m. In this thesis, we explore this interesting connection between minimal string theories and integrable hierarchies further. We uncover the remarkable role that an infinite hierarchy of non-linear differential equations plays in organizing and connecting certain minimal string theories non-perturbatively. We are able to embed the type 0A and 0B (A,A) minimal string theories into this single framework. The string theories arise as special limits of a rich system of equations underpinned by an integrable system known as the dispersive water wave hierarchy. We find that there are several other string-like limits of the system, and conjecture that some of them are type IIA and IIB (A,D) minimal string backgrounds. We explain how these and several other string-like special points arise and are connected. In some cases, the framework endows the theories with a non-perturbative definition for the first time. Notably, we discover that the Painleve IV equation plays a key role in organizing the string theory physics, joining its siblings, Painleve I and II, whose roles have previously been identified in this minimal string context. We then present evidence that the conjectured type II theories have smooth non-perturbative solutions, connecting two perturbative asymptotic regimes, in a 't Hooft limit. Our technique also demonstrates evidence for new minimal string theories that are not apparent in a perturbative analysis.

Bell's Inequalities, Superquantum Correlations, and String Theory

DOE PAGES

Chang, Lay Nam; Lewis, Zachary; Minic, Djordje; ...

2011-01-01

We offermore » an interpretation of superquantum correlations in terms of a “doubly” quantum theory. We argue that string theory, viewed as a quantum theory with two deformation parameters, the string tension α ' , and the string coupling constant g s , is such a superquantum theory that transgresses the usual quantum violations of Bell's inequalities. We also discuss the ℏ → ∞ limit of quantum mechanics in this context. As a superquantum theory, string theory should display distinct experimentally observable supercorrelations of entangled stringy states.« less

Entanglement branes in a two-dimensional string theory

DOE PAGES

Donnelly, William; Wong, Gabriel

2017-09-20

What is the meaning of entanglement in a theory of extended objects such as strings? To address this question we consider the spatial entanglement between two intervals in the Gross-Taylor model, the string theory dual to two-dimensional Yang-Mills theory at large N. The string diagrams that contribute to the entanglement entropy describe open strings with endpoints anchored to the entangling surface, as first argued by Susskind. We develop a canonical theory of these open strings, and describe how closed strings are divided into open strings at the level of the Hilbert space. Here, we derive the modular Hamiltonian for themore » Hartle-Hawking state and show that the corresponding reduced density matrix describes a thermal ensemble of open strings ending on an object at the entangling surface that we call an entanglement brane, or E-brane.« less

On `light' fermions and proton stability in `big divisor' D3/ D7 large volume compactifications

NASA Astrophysics Data System (ADS)

Misra, Aalok; Shukla, Pramod

2011-06-01

Building on our earlier work (Misra and Shukla, Nucl. Phys. B 827:112, 2010; Phys. Lett. B 685:347-352, 2010), we show the possibility of generating "light" fermion mass scales of MeV-GeV range (possibly related to the first two generations of quarks/leptons) as well as eV (possibly related to first two generations of neutrinos) in type IIB string theory compactified on Swiss-Cheese orientifolds in the presence of a mobile space-time filling D3-brane restricted to (in principle) stacks of fluxed D7-branes wrapping the "big" divisor Σ B . This part of the paper is an expanded version of the latter half of Sect. 3 of a published short invited review (Misra, Mod. Phys. Lett. A 26:1, 2011) written by one of the authors [AM]. Further, we also show that there are no SUSY GUT-type dimension-five operators corresponding to proton decay, and we estimate the proton lifetime from a SUSY GUT-type four-fermion dimension-six operator to be 1061 years. Based on GLSM calculations in (Misra and Shukla, Nucl. Phys. B 827:112, 2010) for obtaining the geometric Kähler potential for the "big divisor," using further the Donaldson's algorithm, we also briefly discuss in the first of the two appendices the metric for the Swiss-Cheese Calabi-Yau used, which we obtain and which becomes Ricci flat in the large-volume limit.

Simple Z2 lattice gauge theories at finite fermion density

NASA Astrophysics Data System (ADS)

Prosko, Christian; Lee, Shu-Ping; Maciejko, Joseph

2017-11-01

Lattice gauge theories are a powerful language to theoretically describe a variety of strongly correlated systems, including frustrated magnets, high-Tc superconductors, and topological phases. However, in many cases gauge fields couple to gapless matter degrees of freedom, and such theories become notoriously difficult to analyze quantitatively. In this paper we study several examples of Z2 lattice gauge theories with gapless fermions at finite density, in one and two spatial dimensions, that are either exactly soluble or whose solution reduces to that of a known problem. We consider complex fermions (spinless and spinful) as well as Majorana fermions and study both theories where Gauss' law is strictly imposed and those where all background charge sectors are kept in the physical Hilbert space. We use a combination of duality mappings and the Z2 slave-spin representation to map our gauge theories to models of gauge-invariant fermions that are either free, or with on-site interactions of the Hubbard or Falicov-Kimball type that are amenable to further analysis. In 1D, the phase diagrams of these theories include free-fermion metals, insulators, and superconductors, Luttinger liquids, and correlated insulators. In 2D, we find a variety of gapped and gapless phases, the latter including uniform and spatially modulated flux phases featuring emergent Dirac fermions, some violating Luttinger's theorem.

Novel string field theory with also negative energy constituents/objects gives Veneziano amplitude

NASA Astrophysics Data System (ADS)

Nielsen, H. B.; Ninomiya, M.

2018-02-01

We have proposed a new type of string field theory. The main point of the present article is to cure some technical troubles: missing two out three terms in Veneziano amplitude. Our novel string field theory, describes a theory with many strings in terms of "objects", which are not exactly, but close to Charles Thorn's string bits. The new point is that the objects in terms of which the universe states are constructed, and which have an essentially 26-momentum variable called J μ , can have the energy J 0 be also negative as well as positive. We get a long way in deriving in this model the Veneziano model and obtain all the three terms needed for a four point amplitude. This result strongly indicates that our novel string field theory is indeed string theory.

Minimal left-right symmetric intersecting D-brane model

NASA Astrophysics Data System (ADS)

Anchordoqui, Luis A.; Antoniadis, Ignatios; Goldberg, Haim; Huang, Xing; Lüst, Dieter; Taylor, Tomasz R.

2017-01-01

We investigate left-right symmetric extensions of the standard model based on open strings ending on D-branes, with gauge bosons due to strings attached to stacks of D-branes and chiral matter due to strings stretching between intersecting D-branes. The left-handed and right-handed fermions transform as doublets under S p (1 )L and S p (1 )R, and so their masses must be generated by the introduction of Higgs fields in a bifundamental (2 ,2 ) representation under the two S p (1 ) gauge groups. For such D-brane configurations the left-right symmetry must be broken by Higgs fields in the doublet representation of S p (1 )R and therefore Majorana mass terms are suppressed by some higher physics scale. The left-handed and right-handed neutrinos pair up to form Dirac fermions which control the decay widths of the right-handed W' boson to yield comparable branching fractions into dilepton and dijet channels. Using the most recent searches at LHC13 Run II with 2016 data we constrain the (gR,mW') parameter space. Our analysis indicates that independent of the coupling strength gR, gauge bosons with masses mW'≳3.5 TeV are not ruled out. As the LHC is just beginning to probe the TeV scale, significant room for W' discovery remains.

Bukhvostov-Lipatov model and quantum-classical duality

NASA Astrophysics Data System (ADS)

Bazhanov, Vladimir V.; Lukyanov, Sergei L.; Runov, Boris A.

2018-02-01

The Bukhvostov-Lipatov model is an exactly soluble model of two interacting Dirac fermions in 1 + 1 dimensions. The model describes weakly interacting instantons and anti-instantons in the O (3) non-linear sigma model. In our previous work [arxiv:arXiv:1607.04839] we have proposed an exact formula for the vacuum energy of the Bukhvostov-Lipatov model in terms of special solutions of the classical sinh-Gordon equation, which can be viewed as an example of a remarkable duality between integrable quantum field theories and integrable classical field theories in two dimensions. Here we present a complete derivation of this duality based on the classical inverse scattering transform method, traditional Bethe ansatz techniques and analytic theory of ordinary differential equations. In particular, we show that the Bethe ansatz equations defining the vacuum state of the quantum theory also define connection coefficients of an auxiliary linear problem for the classical sinh-Gordon equation. Moreover, we also present details of the derivation of the non-linear integral equations determining the vacuum energy and other spectral characteristics of the model in the case when the vacuum state is filled by 2-string solutions of the Bethe ansatz equations.

PhD Thesis: String theory in the early universe

NASA Astrophysics Data System (ADS)

Gwyn, Rhiannon

2009-11-01

The intersection of string theory with cosmology is unavoidable in the early universe, and its exploration may shine light on both fields. In this thesis, three papers at this intersection are presented and reviewed, with the aim of providing a thorough and pedagogical guide to their results. First, we address the longstanding problem of finding a string theory realisation of the axion. Using warped compactifications in heterotic string theory, we show that the axion decay constant can be lowered to acceptable values by the warp factor. Next, we move to the subject of cosmic strings, whose network evolution could have important consequences for astrophysics and cosmology. In particular, there are quantitative differences between cosmic superstring networks and GUT cosmic string networks. We investigate the properties of cosmic superstring networks in warped backgrounds, giving the tension and properties of three-string junctions in these backgrounds. Finally, we examine the possibility that cosmic strings in heterotic string theory could be responsible for generating the galactic magnetic fields that seeded those observed today.

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

Donnelly, William; Wong, Gabriel

What is the meaning of entanglement in a theory of extended objects such as strings? To address this question we consider the spatial entanglement between two intervals in the Gross-Taylor model, the string theory dual to two-dimensional Yang-Mills theory at large N. The string diagrams that contribute to the entanglement entropy describe open strings with endpoints anchored to the entangling surface, as first argued by Susskind. We develop a canonical theory of these open strings, and describe how closed strings are divided into open strings at the level of the Hilbert space. Here, we derive the modular Hamiltonian for themore » Hartle-Hawking state and show that the corresponding reduced density matrix describes a thermal ensemble of open strings ending on an object at the entangling surface that we call an entanglement brane, or E-brane.« less

Progress report for a research program in theoretical high energy physics

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

Feldman, D.; Fried, H.M.; Jevicki, A.

This year's research has dealt with: superstrings in the early universe; the invisible axion emissions from SN1987A; quartic interaction in Witten's superstring field theory; W-boson associated multiplicity and the dual parton model; cosmic strings and galaxy formation; cosmic strings and baryogenesis; quark flavor mixing; p -- /bar p/ scattering at TeV energies; random surfaces; ordered exponentials and differential equations; initial value and back-reaction problems in quantum field theory; string field theory and Weyl invariance; the renormalization group and string field theory; the evolution of scalar fields in an inflationary universe, with and without the effects of gravitational perturbations; cosmic stringmore » catalysis of skyrmion decay; inflation and cosmic strings from dynamical symmetry breaking; the physic of flavor mixing; string-inspired cosmology; strings at high-energy densities and complex temperatures; the problem of non-locality in string theory; string statistical mechanics; large-scale structures with cosmic strings and neutrinos; the delta expansion for stochastic quantization; high-energy neutrino flux from ordinary cosmic strings; a physical picture of loop bremsstrahlung; cylindrically-symmetric solutions of four-dimensional sigma models; large-scale structure with hot dark matter and cosmic strings; the unitarization of the odderon; string thermodynamics and conservation laws; the dependence of inflationary-universe models on initial conditions; the delta expansion and local gauge invariance; particle physics and galaxy formation; chaotic inflation with metric and matter perturbations; grand-unified theories, galaxy formation, and large-scale structure; neutrino clustering in cosmic-string-induced wakes; and infrared approximations to nonlinear differential equations. 17 refs.« less

K-theoretic aspects of string theory dualities

NASA Astrophysics Data System (ADS)

Mendez-Diez, Stefan Milo

String theory is a a physical field theory in which point particles are replaced by 1-manifolds propagating in time, called strings. The 2-manifold representing the time evolution of a string is called the string worldsheet. Strings can be either closed (meaning their worldsheets are closed surfaces) or open (meaning their worldsheets have boundary). A D-brane is a submanifold of the spacetime manifold on which string endpoints are constrained to lie. There are five different string theories that have supersymmetry, and they are all related by various dualities. This dissertation will review how D-branes are classified by K-theory. We will then explore the K-theoretic aspects of a hypothesized duality between the type I theory compactified on a 4-torus and the type IIA theory compactified on a K3 surface, by looking at a certain blow down of the singular limit of K3. This dissertation concludes by classifying D-branes on the type II orientifold Tn/Z2 when the Z2 action is multiplication by -1 and the H-flux is trivial. We find that classifying D-branes on the singular limit of K3, T4/Z2 by equivariant K-theory agrees with the classification of D-branes on a smooth K3 surface by ordinary K-theory.

Classification of compactified su( N c ) gauge theories with fermions in all representations

NASA Astrophysics Data System (ADS)

Anber, Mohamed M.; Vincent-Genod, Loïc

2017-12-01

We classify su( N c ) gauge theories on R^3× S^1 with massless fermions in higher representations obeying periodic boundary conditions along S^1 . In particular, we single out the class of theories that is asymptotically free and weakly coupled in the infrared, and therefore, is amenable to semi-classical treatment. Our study is conducted by carefully identifying the vacua inside the affine Weyl chamber using Verma bases and Frobenius formula techniques. Theories with fermions in pure representations are generally strongly coupled. The only exceptions are the four-index symmetric representation of su(2) and adjoint representation of su( N c ). However, we find a plethora of admissible theories with fermions in mixed representations. A sub-class of these theories have degenerate perturbative vacua separated by domain walls. In particular, su( N c ) theories with fermions in the mixed representations adjoint⊕fundamental and adjoint⊕two-index symmetric admit degenerate vacua that spontaneously break the parity P , charge conjugation C , and time reversal T symmetries. These are the first examples of strictly weakly coupled gauge theories on R^3× S^1 with spontaneously broken C , P , and T symmetries. We also compute the fermion zero modes in the background of monopole-instantons. The monopoles and their composites (topological molecules) proliferate in the vacuum leading to the confinement of electric charges. Interestingly enough, some theories have also accidental degenerate vacua, which are not related by any symmetry. These vacua admit different numbers of fermionic zero modes, and hence, different kinds of topological molecules. The lack of symmetry, however, indicates that such degeneracy might be lifted by higher order corrections. Finally, we study the general phase structure of adjoint⊕fundamental theories in the small circle and decompactification limits.

On D-brane -anti D-brane effective actions and their all order bulk singularity structures

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

Hatefi, Ehsan; Institute for Theoretical Physics, TU Wien,Wiedner Hauptstrasse 8-10/136, A-1040 Vienna

All four point functions of brane anti brane system including their correct all order α{sup ′} corrections have been addressed. All five point functions of one closed string Ramond-Ramond (RR), two real tachyons and either one gauge field or the scalar field in both symmetric and asymmetric pictures have also been explored. The entire analysis of is carried out. Not only does it fix the vertex operator of RR in asymmetric picture and in higher point functions of string theory amplitudes but also it confirms the fact that there is no issue of picture dependence of the mixed closed RR,more » gauge fields, tachyons and fermion fields in all symmetric or anti symmetric ones. We compute S-matrix in the presence of a transverse scalar field, two real tachyons and that reveals two different kinds of bulk singularity structures, involving an infinite number of u-channel gauge field and (u+s{sup ′}+t{sup ′})-channel scalar bulk poles. In order to produce all those bulk singularity structures, we define various couplings at the level of the effective field theory that involve the mixing term of Chern-Simons coupling (with C-potential field) and a covariant derivative of the scalar field that comes from the pull-back of brane. Eventually we explore their all order α{sup ′} corrections in the presence of brane anti brane system where various remarks will be also pointed out.« less

The Hottest, and Most Liquid, Liquid in the Universe

NASA Astrophysics Data System (ADS)

Rajagopal, Krishna

2012-03-01

What was the universe like microseconds after the big bang? At very high temperatures, protons and neutrons fall apart --- the quarks that are ordinarily confined within them are freed. Before experiments at the Relativistic Heavy Ion Collider started recreating little droplets of big bang matter, it was thought to be a tenuous gas-like plasma. Now we know from experiments at RHIC and at the Large Hadron Collider that at these extreme temperatures nature serves up hot quark soup --- the hottest liquid in the universe and the liquid that flows with the least dissipation. The only other comparably liquid liquid is the coldest liquid in the universe, namely the fluid made of trapped fermionic atoms at microKelvin rather than TeraKelvin temperatures. These are two examples of strongly coupled fluids without any apparent quasiparticle description, a feature that they share with other phases of matter like the strange metal phase of the cuprate superconductors that aren't conventionally thought of as liquids but that are equally challenging to understand. I will describe how physicists are using RHIC and LHC experiments --- as well as calculations done using dualities between liquids and black holes discovered in string theory --- to discern the properties of hot quark soup. In this domain, string theory is answering questions posed by laboratory experiments. I will describe the opportunities and challenges for coming experiments at RHIC and the LHC, chief among them being understanding how a liquid with no apparent particulate description emerges from quarks and gluons.

A note on closed-string interactions a la witten

NASA Astrophysics Data System (ADS)

Romans, L. J.

1987-08-01

We consider the problem of formulating a field theory of interacting closed strings analogous to Witten's open-string field theory. Two natural candidates have been suggested for an off-shell three-string interaction vertex: one scheme involves a cyclic geometric overlap in spacetime, while the other is obtained by ``stuttering'' the Fock-space realization of the open-string vertex. We demonstrate that these two approaches are in fact equivalent, utilizing the operator formalism as developed to describe Witten's theory. Implications of this result for the construction of closed-string theories are briefly discussed. Address after August 1, 1987: Department of Physics, University of Southern California, Los Angeles, CA 90089, USA.

Worldsheet factorization for twistor-strings

NASA Astrophysics Data System (ADS)

Adamo, Tim

2014-04-01

We study the multiparticle factorization properties of two worldsheet theories which — at tree-level — describe the scattering of massless particles in four dimensions: the Berkovits-Witten twistor-string for = 4 super-Yang-Mills coupled to = 4 conformal supergravity, and the Skinner twistor-string for = 8 supergravity. By considering these string-like theories, we can study factorization at the level of the worldsheet before any Wick contractions or integrals have been performed; this is much simpler than considering the factorization properties of the amplitudes themselves. In Skinner's twistor-string this entails the addition of worldsheet gravity as well as a formalism that represents all external states in a manifestly symmetric way, which we develop explicitly at genus zero. We confirm that the scattering amplitudes of Skinner's theory, as well as the gauge theory amplitudes for the planar sector of the Berkovits-Witten theory, factorize appropriately at genus zero. In the non-planar sector, we find behavior indicative of conformal gravity in the Berkovits-Witten twistor-string. We contrast factorization in twistor-strings with the story in ordinary string theory, and also make some remarks on higher genus factorization and disconnected prescriptions.

Dark solitons, D-branes and noncommutative tachyon field theory

NASA Astrophysics Data System (ADS)

Giaccari, Stefano; Nian, Jun

2017-11-01

In this paper we discuss the boson/vortex duality by mapping the (3+1)D Gross-Pitaevskii theory into an effective string theory in the presence of boundaries. Via the effective string theory, we find the Seiberg-Witten map between the commutative and the noncommutative tachyon field theories, and consequently identify their soliton solutions with D-branes in the effective string theory. We perform various checks of the duality map and the identification of soliton solutions. This new insight between the Gross-Pitaevskii theory and the effective string theory explains the similarity of these two systems at quantitative level.

Book Review

NASA Astrophysics Data System (ADS)

Rickles, Dean

Although ostensibly a festschrift for Gabriele Veneziano, this book also marks an important step in the historical study of string theory, featuring several excellent chapters on the earliest period of string theory, as it emerged from the study of strong interaction physics and dual resonance models. Veneziano is often crowned 'the father of string theory' since it was he who discovered the amplitude that led to the dual resonance models that then led to string theory in something like the form we know it today (though not immediately into a quantum theory of gravity). However, as the historical articles in this book make plain, Veneziano was but a small (albeit vital) component in the creation of string theory.

Discovery of proton decay: A must for theory, a challenge for experiment

NASA Astrophysics Data System (ADS)

Pati, Jogesh C.

2000-08-01

It is noted that, but for one missing piece—proton decay—the evidence in support of grand unification is now strong. It includes: (i) the observed family-structure, (ii) the meeting of the gauge couplings, (iii) neutrino-oscillations, (iv) the intricate pattern of the masses and mixings of all fermions, including the neutrinos, and (v) the need for B-L as a generator, to implement baryogenesis. Taken together, these not only favor grand unification but in fact select out a particular route to such unification, based on the ideas of supersymmetry, SU(4)-color and left-right symmetry. Thus they point to the relevance of an effective string-unified G(224) or SO(10)-symmetry. A concrete proposal is presented, within a predictive SO(10)/G(224)-framework, that successfully describes the masses and mixings of all fermions, including the neutrinos—with eight predictions, all in agreement with observation. Within this framework, a systematic study of proton decay is carried out, which pays special attention to its dependence on the fermion masses, including the superheavy Majorana masses of the right-handed neutrinos. The study shows that a conservative upper limit on the proton lifetime is about (1/2-1)×1034yrs, with ν¯K+ being the dominant decay mode, and as a distinctive feature, μ+K0 being prominent. This in turn strongly suggests that an improvement in the current sensitivity by a factor of five to ten (compared to SuperK) ought to reveal proton decay. Otherwise some promising and remarkably successful ideas on unification would suffer a major setback.

Non-perturbative String Theory from Water Waves

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

Iyer, Ramakrishnan; Johnson, Clifford V.; /Southern California U.

2012-06-14

We use a combination of a 't Hooft limit and numerical methods to find non-perturbative solutions of exactly solvable string theories, showing that perturbative solutions in different asymptotic regimes are connected by smooth interpolating functions. Our earlier perturbative work showed that a large class of minimal string theories arise as special limits of a Painleve IV hierarchy of string equations that can be derived by a similarity reduction of the dispersive water wave hierarchy of differential equations. The hierarchy of string equations contains new perturbative solutions, some of which were conjectured to be the type IIA and IIB string theoriesmore » coupled to (4, 4k ? 2) superconformal minimal models of type (A, D). Our present paper shows that these new theories have smooth non-perturbative extensions. We also find evidence for putative new string theories that were not apparent in the perturbative analysis.« less

Democratic Superstring Field Theory and Its Gauge Fixing

NASA Astrophysics Data System (ADS)

Kroyter, M.

This work is my contribution to the proceedings of the conference``SFT2010 -- the third international conference on string field theory and related topics'' and it reflects my talk there, which described the democratic string field theory and its gauge fixing. The democratic string field theory is the only fully RNS string field theory to date. It lives in the large Hilbert space and includes all picture numbers. Picture changing amounts in this formalism to a gauge transformation. We describe the theory and its properties and show that when partially gauge fixed it can be reduced to the modified theory and to the non-polynomial theory. In the latter case we can even include the Ramond sector in the picture-fixed action. We also show that another partial gauge-fixing leads to a new consistent string field theory at picture number -1.

Spin chains and string theory.

PubMed

Kruczenski, Martin

2004-10-15

Recently, an important test of the anti de Sitter/conformal field theory correspondence has been done using rotating strings with two angular momenta. We show that such a test can be described more generally as the agreement between two actions: one a low energy description of a spin chain appearing in the field theory side, and the other a limit of the string action in AdS5xS5. This gives a map between the mean value of the spin in the boundary theory and the position of the string in the bulk, and shows how a string action can emerge from a gauge theory in the large-N limit.

A superstring field theory for supergravity

NASA Astrophysics Data System (ADS)

Reid-Edwards, R. A.; Riccombeni, D. A.

2017-09-01

A covariant closed superstring field theory, equivalent to classical tendimensional Type II supergravity, is presented. The defining conformal field theory is the ambitwistor string worldsheet theory of Mason and Skinner. This theory is known to reproduce the scattering amplitudes of Cachazo, He and Yuan in which the scattering equations play an important role and the string field theory naturally incorporates these results. We investigate the operator formalism description of the ambitwsitor string and propose an action for the string field theory of the bosonic and supersymmetric theories. The correct linearised gauge symmetries and spacetime actions are explicitly reproduced and evidence is given that the action is correct to all orders. The focus is on the NeveuSchwarz sector and the explicit description of tree level perturbation theory about flat spacetime. Application of the string field theory to general supergravity backgrounds and the inclusion of the Ramond sector are briefly discussed.

Fermionic Spinon Theory of Square Lattice Spin Liquids near the Néel State

NASA Astrophysics Data System (ADS)

Thomson, Alex; Sachdev, Subir

2018-01-01

Quantum fluctuations of the Néel state of the square lattice antiferromagnet are usually described by a CP1 theory of bosonic spinons coupled to a U(1) gauge field, and with a global SU(2) spin rotation symmetry. Such a theory also has a confining phase with valence bond solid (VBS) order, and upon including spin-singlet charge-2 Higgs fields, deconfined phases with Z2 topological order possibly intertwined with discrete broken global symmetries. We present dual theories of the same phases starting from a mean-field theory of fermionic spinons moving in π flux in each square lattice plaquette. Fluctuations about this π -flux state are described by (2 +1 )-dimensional quantum chromodynamics (QCD3 ) with a SU(2) gauge group and Nf=2 flavors of massless Dirac fermions. It has recently been argued by Wang et al. [Deconfined Quantum Critical Points: Symmetries and Dualities, Phys. Rev. X 7, 031051 (2017)., 10.1103/PhysRevX.7.031051] that this QCD3 theory describes the Néel-VBS quantum phase transition. We introduce adjoint Higgs fields in QCD3 and obtain fermionic dual descriptions of the phases with Z2 topological order obtained earlier using the bosonic CP1 theory. We also present a fermionic spinon derivation of the monopole Berry phases in the U(1) gauge theory of the VBS state. The global phase diagram of these phases contains multicritical points, and our results imply new boson-fermion dualities between critical gauge theories of these points.

Free field theory as a string theory?

NASA Astrophysics Data System (ADS)

Gopakumar, Rajesh

2004-11-01

An approach to systematically implement open-closed string duality for free large N gauge theories is summarised. We show how the relevant closed string moduli space emerges from a reorganisation of the Feynman diagrams contributing to free field correlators. We also indicate why the resulting integrand on moduli space has the right features to be that of a string theory on AdS. To cite this article: R. Gopakumar, C. R. Physique 5 (2004).

Holography and noncommutative yang-mills theory

PubMed

Li; Wu

2000-03-06

In this Letter a recently proposed gravity dual of noncommutative Yang-Mills theory is derived from the relations between closed string moduli and open string moduli recently suggested by Seiberg and Witten. The only new input one needs is a simple form of the running string tension as a function of energy. This derivation provides convincing evidence that string theory integrates with the holographical principle and demonstrates a direct link between noncommutative Yang-Mills theory and holography.

Eventful horizons: String theory in de Sitter and anti-de Sitter

NASA Astrophysics Data System (ADS)

Kleban, Matthew Benjamin

String theory purports to be a theory of quantum gravity. As such, it should have much to say about the deep mysteries surrounding the very early stages of our universe. For this reason, although the theory is notoriously difficult to directly test, data from experimental cosmology may provide a way to probe the high energy physics of string theory. In the first part of this thesis, I will address the important issue of the testability of string theory using observations of the cosmic microwave background radiation. In the second part, I will study some formal difficulties that arise in attempting to understand string theory in de Sitter spacetime. In the third part, I will study the singularity of an eternal anti de Sitter Schwarzschild black hole, using the AdS/CFT correspondence.

Fermion-number violation in regularizations that preserve fermion-number symmetry

NASA Astrophysics Data System (ADS)

Golterman, Maarten; Shamir, Yigal

2003-01-01

There exist both continuum and lattice regularizations of gauge theories with fermions which preserve chiral U(1) invariance (“fermion number”). Such regularizations necessarily break gauge invariance but, in a covariant gauge, one recovers gauge invariance to all orders in perturbation theory by including suitable counterterms. At the nonperturbative level, an apparent conflict then arises between the chiral U(1) symmetry of the regularized theory and the existence of ’t Hooft vertices in the renormalized theory. The only possible resolution of the paradox is that the chiral U(1) symmetry is broken spontaneously in the enlarged Hilbert space of the covariantly gauge-fixed theory. The corresponding Goldstone pole is unphysical. The theory must therefore be defined by introducing a small fermion-mass term that breaks explicitly the chiral U(1) invariance and is sent to zero after the infinite-volume limit has been taken. Using this careful definition (and a lattice regularization) for the calculation of correlation functions in the one-instanton sector, we show that the ’t Hooft vertices are recovered as expected.

``SO what Will you do if String Theory is WRONG?''

NASA Astrophysics Data System (ADS)

Emam, Moataz H.

2008-07-01

I briefly discuss the accomplishments of string theory that would survive a complete falsification of the theory as a model of nature and argue the possibility that such a survival may necessarily mean that string theory would become its own discipline, independently of both physics and mathematics.

String Theory: Big Problem for Small Size

ERIC Educational Resources Information Center

Sahoo, S.

2009-01-01

String theory is the most promising candidate theory for a unified description of all the fundamental forces that exist in nature. It provides a mathematical framework that combines quantum theory with Einstein's general theory of relativity. The typical size of a string is of the order of 10[superscript -33] cm, called the Planck length. But due…

Cosmological singularities and bounce in Cartan-Einstein theory

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

Lucat, Stefano; Prokopec, Tomislav, E-mail: s.lucat@students.uu.nl, E-mail: t.prokopec@uu.nl

We consider a generalized Einstein-Cartan theory, in which we add the unique covariant dimension four operators to general relativity that couples fermionic spin current to the torsion tensor (with an arbitrary strength). Since torsion is local and non-dynamical, when integrated out it yields an effective four-fermion interaction of the gravitational strength. We show how to renormalize the theory, in the one-loop perturbative expansion in generally curved space-times, obtaining the first order correction to the 2PI effective action in Schwinger-Keldysh ( in-in ) formalism. We then apply the renormalized theory to study the dynamics of a collapsing universe that begins inmore » a thermal state and find that—instead of a big crunch singularity—the Universe with torsion undergoes a bounce . We solve the dynamical equations (a) classically (without particle production); (b) including the production of fermions in a fixed background in the Hartree-Fock approximation and (c) including the quantum backreaction of fermions onto the background space-time. In the first and last cases the Universe undergoes a bounce. The production of fermions due to the coupling to a contracting homogeneous background speeds up the bounce, implying that the quantum contributions from fermions is negative, presumably because fermion production contributes negatively to the energy-momentum tensor. When compared with former works on the subject, our treatment is fully microscopic (namely, we treat fermions by solving the corresponding Dirac equations) and quantum (in the sense that we include fermionic loop contributions).« less

Cosmological singularities and bounce in Cartan-Einstein theory

NASA Astrophysics Data System (ADS)

Lucat, Stefano; Prokopec, Tomislav

2017-10-01

We consider a generalized Einstein-Cartan theory, in which we add the unique covariant dimension four operators to general relativity that couples fermionic spin current to the torsion tensor (with an arbitrary strength). Since torsion is local and non-dynamical, when integrated out it yields an effective four-fermion interaction of the gravitational strength. We show how to renormalize the theory, in the one-loop perturbative expansion in generally curved space-times, obtaining the first order correction to the 2PI effective action in Schwinger-Keldysh (in-in) formalism. We then apply the renormalized theory to study the dynamics of a collapsing universe that begins in a thermal state and find that—instead of a big crunch singularity—the Universe with torsion undergoes a bounce. We solve the dynamical equations (a) classically (without particle production); (b) including the production of fermions in a fixed background in the Hartree-Fock approximation and (c) including the quantum backreaction of fermions onto the background space-time. In the first and last cases the Universe undergoes a bounce. The production of fermions due to the coupling to a contracting homogeneous background speeds up the bounce, implying that the quantum contributions from fermions is negative, presumably because fermion production contributes negatively to the energy-momentum tensor. When compared with former works on the subject, our treatment is fully microscopic (namely, we treat fermions by solving the corresponding Dirac equations) and quantum (in the sense that we include fermionic loop contributions).

Galileon string measure and other modified measure extended objects

NASA Astrophysics Data System (ADS)

Vulfs, T. O.; Guendelman, E. I.

2017-12-01

We show that it is possible to formulate string theory as a “Galileon string theory”. The Galileon field χ enters in the definition of the integration measure in the action. Following the methods of the modified measure string theory, we find that the final equations are again those of the sigma-model. Moreover, the string tension appears again as an additional dynamical degree of freedom. At the same time, the theory satisfies all requirements of the Galileon higher derivative theory at the action level while the equations of motion are still of the second-order. A Galileon symmetry is displayed explicitly in the conformal string worldsheet frame. Also, we define the Galileon gauge transformations. Generalizations to branes with other modified measures are discussed.

p-adic string theories provide lattice Discretization to the ordinary string worldsheet.

PubMed

Ghoshal, Debashis

2006-10-13

A class of models called p-adic strings is useful in understanding the tachyonic instability of string theory. These are found to be empirically related to the ordinary strings in the p-->1 limit. We propose that these models provide discretization for the string worldsheet and argue that the limit is naturally thought of as a continuum limit in the sense of the renormalization group.

p-adic String Theories Provide Lattice Discretization to the Ordinary String Worldsheet

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

Ghoshal, Debashis

2006-10-13

A class of models called p-adic strings is useful in understanding the tachyonic instability of string theory. These are found to be empirically related to the ordinary strings in the p{yields}1 limit. We propose that these models provide discretization for the string worldsheet and argue that the limit is naturally thought of as a continuum limit in the sense of the renormalization group.

M-theoretic derivations of 4d-2d dualities: from a geometric Langlands duality for surfaces, to the AGT correspondence, to integrable systems

NASA Astrophysics Data System (ADS)

Tan, Meng-Chwan

2013-07-01

In part I, we extend our analysis in [arXiv:0807.1107], and show that a mathematically conjectured geometric Langlands duality for complex surfaces in [1], and its generalizations — which relate some cohomology of the moduli space of certain ("ramified") G-instantons to the integrable representations of the Langlands dual of certain affine (sub) G-algebras, where G is any compact Lie group — can be derived, purely physically, from the principle that the spacetime BPS spectra of string-dual M-theory compactifications ought to be equivalent. In part II, to the setup in part I, we introduce Omega-deformation via fluxbranes and add half-BPS boundary defects via M9-branes, and show that the celebrated AGT correspondence in [2, 3], and its generalizations — which essentially relate, among other things, some equivariant cohomology of the moduli space of certain ("ramified") G-instantons to the integrable representations of the Langlands dual of certain affine -algebras — can likewise be derived from the principle that the spacetime BPS spectra of string-dual M-theory compactifications ought to be equivalent. In part III, we consider various limits of our setup in part II, and connect our story to chiral fermions and integrable systems. Among other things, we derive the NekrasovOkounkov conjecture in [4] — which relates the topological string limit of the dual Nekrasov partition function for pure G to the integrable representations of the Langlands dual of an affine G-algebra — and also demonstrate that the Nekrasov-Shatashvili limit of the "fullyramified" Nekrasov instanton partition function for pure G is a simultaneous eigenfunction of the quantum Toda Hamiltonians associated with the Langlands dual of an affine G-algebra. Via the case with matter, we also make contact with Hitchin systems and the "ramified" geometric Langlands correspondence for curves.

[ital N]-string vertices in string field theory

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

Bordes, J.; Abdurrahman, A.; Anton, F.

1994-03-15

We give the general form of the vertex corresponding to the interaction of an arbitrary number of strings. The technique employed relies on the comma'' representation of string field theory where string fields and interactions are represented as matrices and operations between them such as multiplication and trace. The general formulation presented here shows that the interaction vertex of [ital N] strings, for any arbitrary [ital N], is given as a function of particular combinations of matrices corresponding to the change of representation between the full string and the half string degrees of freedom.

Causal fermion systems as a candidate for a unified physical theory

NASA Astrophysics Data System (ADS)

Finster, Felix; Kleiner, Johannes

2015-07-01

The theory of causal fermion systems is an approach to describe fundamental physics. Giving quantum mechanics, general relativity and quantum field theory as limiting cases, it is a candidate for a unified physical theory. We here give a non-technical introduction.

Elliptic genus of E-strings

NASA Astrophysics Data System (ADS)

Kim, Joonho; Kim, Seok; Lee, Kimyeong; Park, Jaemo; Vafa, Cumrun

2017-09-01

We study a family of 2d N=(0, 4) gauge theories which describes at low energy the dynamics of E-strings, the M2-branes suspended between a pair of M5 and M9 branes. The gauge theory is engineered using a duality with type IIA theory, leading to the D2-branes suspended between an NS5-brane and 8 D8-branes on an O8-plane. We compute the elliptic genus of this family of theories, and find agreement with the known results for single and two E-strings. The partition function can in principle be computed for arbitrary number of E-strings, and we compute them explicitly for low numbers. We test our predictions against the partially known results from topological strings, as well as from the instanton calculus of 5d Sp(1) gauge theory. Given the relation to topological strings, our computation provides the all genus partition function of the refined topological strings on the canonical bundle over 1/2K3.

Relativistic strings - From soap films to a grand unified theory

NASA Astrophysics Data System (ADS)

Nesterenko, V. V.

1986-11-01

The concept of relativistic strings is considered in connection with the theory of minimal surfaces (e.g., soap films stretched onto closed wire contours). The role of relativistic strings in hadron physics is discussed. Attention is then given to the creation of a grand unified theory on the basis of the superstring concept. Finally, the role of relativistic strings in cosmology is examined.

Quantum space foam and string theory

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

Nekrasov, Nikita

2006-11-03

String theory is originally defined as a modification of the Feynman rules in perturbation theory. It contains gravity in its perturbative spectrum. We review some recent developments which demonstrate that nonperturbative effects of quantum gravity, such as spacetime foam, arise in string theory as well.Prepared for the proceedings of 'Albert Einstein Century Conference' , Paris July 2005.

String model for the dynamics of glass-forming liquids

PubMed Central

Pazmiño Betancourt, Beatriz A.; Douglas, Jack F.; Starr, Francis W.

2014-01-01

We test the applicability of a living polymerization theory to describe cooperative string-like particle rearrangement clusters (strings) observed in simulations of a coarse-grained polymer melt. The theory quantitatively describes the interrelation between the average string length L, configurational entropy Sconf, and the order parameter for string assembly Φ without free parameters. Combining this theory with the Adam-Gibbs model allows us to predict the relaxation time τ in a lower temperature T range than accessible by current simulations. In particular, the combined theories suggest a return to Arrhenius behavior near Tg and a low T residual entropy, thus avoiding a Kauzmann “entropy crisis.” PMID:24880303

String model for the dynamics of glass-forming liquids.

PubMed

Pazmiño Betancourt, Beatriz A; Douglas, Jack F; Starr, Francis W

2014-05-28

We test the applicability of a living polymerization theory to describe cooperative string-like particle rearrangement clusters (strings) observed in simulations of a coarse-grained polymer melt. The theory quantitatively describes the interrelation between the average string length L, configurational entropy Sconf, and the order parameter for string assembly Φ without free parameters. Combining this theory with the Adam-Gibbs model allows us to predict the relaxation time τ in a lower temperature T range than accessible by current simulations. In particular, the combined theories suggest a return to Arrhenius behavior near Tg and a low T residual entropy, thus avoiding a Kauzmann "entropy crisis."

String Scale Gauge Coupling Unification with Vector-Like Exotics and Noncanonical U(1)Y Normalization

NASA Astrophysics Data System (ADS)

Barger, V.; Jiang, Jing; Langacker, Paul; Li, Tianjun

We use a new approach to study string scale gauge coupling unification systematically, allowing both the possibility of noncanonical U(1)Y normalization and the existence of vector-like particles whose quantum numbers are the same as those of the Standard Model (SM) fermions and their Hermitian conjugates and the SM adjoint particles. We first give all the independent sets (Yi) of particles that can be employed to achieve SU(3)C and SU(2)L string scale gauge coupling unification and calculate their masses. Second, for a noncanonical U(1)Y normalization, we obtain string scale SU(3)C ×SU(2)L ×U(1)Y gauge coupling unification by choosing suitable U(1)Y normalizations for each of the Yi sets. Alternatively, for the canonical U(1)Y normalization, we achieve string scale gauge coupling unification by considering suitable combinations of the Yi sets or by introducing additional independent sets (Zi), that do not affect the SU(3)C ×SU(2)L unification at tree level, and then choosing suitable combinations, one from the Yi sets and one from the Zi sets. We also briefly discuss string scale gauge coupling unification in models with higher Kac-Moody levels for SU(2)L or SU(3)C.

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

Harmark, Troels; Orselli, Marta

We match the Hagedorn/deconfinement temperature of planar N=4 super Yang-Mills (SYM) on RxS{sup 3} to the Hagedorn temperature of string theory on AdS{sub 5}xS{sup 5}. The match is done in a near-critical region where both gauge theory and string theory are weakly coupled. The near-critical region is near a point with zero temperature and critical chemical potential. On the gauge-theory side we are taking a decoupling limit found in Ref. 7 in which the physics of planar N=4 SYM is given exactly by the ferromagnetic XXX{sub 1/2} Heisenberg spin chain. We find moreover a general relation between the Hagedorn/deconfinement temperaturemore » and the thermodynamics of the Heisenberg spin chain and we use this to compute it in two distinct regimes. On the string-theory side, we identify the dual limit for which the string tension and string coupling go to zero. This limit is taken of string theory on a maximally supersymmetric pp-wave background with a flat direction, obtained from a Penrose limit of AdS{sub 5}xS{sup 5}. We compute the Hagedorn temperature of the string theory and find agreement with the Hagedorn/deconfinement temperature computed on the gauge-theory side.« less

Note on tachyon actions in string theory

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

Headrick, Matthew

2009-02-15

A number of spacetime fields in string theory (notably the metric, dilaton, bosonic and type 0 bulk closed-string tachyon, and bosonic open-string tachyon) have the following property: whenever the spacetime field configuration factorizes in an appropriate sense, the matter sector of the world-sheet theory factorizes into a tensor product of two decoupled theories. Since the beta functions for such a product theory necessarily also factorize, this property strongly constrains the form of the spacetime action encoding those beta functions. We show that this constraint alone--without needing actually to compute any of the beta functions--is sufficient to fix the form ofmore » the two-derivative action for the metric-dilaton system, as well as the potential for the bosonic open-string tachyon. We also show that no action consistent with this constraint exists for the closed-string tachyon coupled to the metric and dilaton.« less

Gödel universes in string theory

NASA Astrophysics Data System (ADS)

Barrow, John D.; Dabrowski, Mariusz P.

1998-11-01

We show that homogeneous Gödel spacetimes need not contain closed timelike curves in low-energy-effective string theories. We find exact solutions for the Gödel metric in string theory for the full O(α') action including both dilaton and axion fields. The results are valid for bosonic, heterotic and super-strings. To first order in the inverse string tension α', these solutions display a simple relation between the angular velocity of the Gödel universe, Ω, and the inverse string tension of the form α'=1/Ω2 in the absence of the axion field. The generalization of this relationship is also found when the axion field is present.

From decay to complete breaking: pulling the strings in SU(2) Yang-Mills theory.

PubMed

Pepe, M; Wiese, U-J

2009-05-15

We study {2Q+1} strings connecting two static charges Q in (2+1)D SU(2) Yang-Mills theory. While the fundamental {2} string between two charges Q=1/2 is unbreakable, the adjoint {3} string connecting two charges Q=1 can break. When a {4} string is stretched beyond a critical length, it decays into a {2} string by gluon pair creation. When a {5} string is stretched, it first decays into a {3} string, which eventually breaks completely. The energy of the screened charges at the ends of a string is well described by a phenomenological constituent gluon model.

Higher-Loop Amplitude Monodromy Relations in String and Gauge Theory.

PubMed

Tourkine, Piotr; Vanhove, Pierre

2016-11-18

The monodromy relations in string theory provide a powerful and elegant formalism to understand some of the deepest properties of tree-level field theory amplitudes, like the color-kinematics duality. This duality has been instrumental in tremendous progress on the computations of loop amplitudes in quantum field theory, but a higher-loop generalization of the monodromy construction was lacking. In this Letter, we extend the monodromy relations to higher loops in open string theory. Our construction, based on a contour deformation argument of the open string diagram integrands, leads to new identities that relate planar and nonplanar topologies in string theory. We write one and two-loop monodromy formulas explicitly at any multiplicity. In the field theory limit, at one-loop we obtain identities that reproduce known results. At two loops, we check our formulas by unitarity in the case of the four-point N=4 super-Yang-Mills amplitude.

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

NASA Astrophysics Data System (ADS)

Duret, Q.; Machet, B.

2010-10-01

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

Windings of twisted strings

NASA Astrophysics Data System (ADS)

Casali, Eduardo; Tourkine, Piotr

2018-03-01

Twistor string models have been known for more than a decade now but have come back under the spotlight recently with the advent of the scattering equation formalism which has greatly generalized the scope of these models. A striking ubiquitous feature of these models has always been that, contrary to usual string theory, they do not admit vibrational modes and thus describe only conventional field theory. In this paper we report on the surprising discovery of a whole new sector of one of these theories which we call "twisted strings," when spacetime has compact directions. We find that the spectrum is enhanced from a finite number of states to an infinite number of interacting higher spin massive states. We describe both bosonic and world sheet supersymmetric models, their spectra and scattering amplitudes. These models have distinctive features of both string and field theory, for example they are invariant under stringy T-duality but have the high energy behavior typical of field theory. Therefore they describe a new kind of field theories in target space, sitting on their own halfway between string and field theory.

Running coupling from gluon and ghost propagators in the Landau gauge: Yang-Mills theories with adjoint fermions

NASA Astrophysics Data System (ADS)

Bergner, Georg; Piemonte, Stefano

2018-04-01

Non-Abelian gauge theories with fermions transforming in the adjoint representation of the gauge group (AdjQCD) are a fundamental ingredient of many models that describe the physics beyond the Standard Model. Two relevant examples are N =1 supersymmetric Yang-Mills (SYM) theory and minimal walking technicolor, which are gauge theories coupled to one adjoint Majorana and two adjoint Dirac fermions, respectively. While confinement is a property of N =1 SYM, minimal walking technicolor is expected to be infrared conformal. We study the propagators of ghost and gluon fields in the Landau gauge to compute the running coupling in the MiniMom scheme. We analyze several different ensembles of lattice Monte Carlo simulations for the SU(2) adjoint QCD with Nf=1 /2 ,1 ,3 /2 , and 2 Dirac fermions. We show how the running of the coupling changes as the number of interacting fermions is increased towards the conformal window.

A four-dimensional model with the fermionic determinant exactly evaluated

NASA Astrophysics Data System (ADS)

Mignaco, J. A.; Rego Monteiro, M. A.

1986-07-01

A method is presented to compute the fermion determinant of some class of field theories. By this method the following results of the fermion determinant in two dimensions are easily recovered: (i) Schwinger model without reference to a particular gauge. (ii) QCD in the light-cone gauge. (iii) Gauge invariant result of QCD. The method is finally applied to give an analytical solution of the fermion determinant of a four-dimensional, non-abelian, Dirac-like theory with massless fermions interacting with an external vector field through a pseudo-vectorial coupling. Fellow of the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), Brazil.

Beyond the Standard Model IV

NASA Astrophysics Data System (ADS)

Gunion, John F.; Han, Tao; Ohnemus, James

1995-08-01

The Table of Contents for the book is as follows: * Preface * Organizing and Advisory Committees * PLENARY SESSIONS * Looking Beyond the Standard Model from LEP1 and LEP2 * Virtual Effects of Physics Beyond the Standard Model * Extended Gauge Sectors * CLEO's Views Beyond the Standard Model * On Estimating Perturbative Coefficients in Quantum Field Theory and Statistical Physics * Perturbative Corrections to Inclusive Heavy Hadron Decay * Some Recent Developments in Sphalerons * Searching for New Matter Particles at Future Colliders * Issues in Dynamical Supersymmetry Breaking * Present Status of Fermilab Collider Accelerator Upgrades * The Extraordinary Scientific Opportunities from Upgrading Fermilab's Luminosity ≥ 1033 cm-2 sec-1 * Applications of Effective Lagrangians * Collider Phenomenology for Strongly Interacting Electroweak Sector * Physics of Self-Interacting Electroweak Bosons * Particle Physics at a TeV-Scale e+e- Linear Collider * Physics at γγ and eγ Colliders * Challenges for Non-Minimal Higgs Searchers at Future Colliders * Physics Potential and Development of μ+μ- Colliders * Beyond Standard Quantum Chromodynamics * Extracting Predictions from Supergravity/Superstrings for the Effective Theory Below the Planck Scale * Non-Universal SUSY Breaking, Hierarchy and Squark Degeneracy * Supersymmetric Phenomenology in the Light of Grand Unification * A Survey of Phenomenological Constraints on Supergravity Models * Precision Tests of the MSSM * The Search for Supersymmetry * Neutrino Physics * Neutrino Mass: Oscillations and Hot Dark Matter * Dark Matter and Large-Scale Structure * Electroweak Baryogenesis * Progress in Searches for Non-Baryonic Dark Matter * Big Bang Nucleosynthesis * Flavor Tests of Quark-Lepton * Where are We Coming from? What are We? Where are We Going? * Summary, Perspectives * PARALLEL SESSIONS * SUSY Phenomenology I * Is Rb Telling us that Superpartners will soon be Discovered? * Dark Matter in Constrained Minimal Supersymmetry * A Fourth Family in the MSSM? * Multi-channel Search for Supergravity at the Large Hadron Collider * Precise Predictions for Masses and Couplings in the Minimal Supersymmetric Standard Model * Radiative b Decays and the Detection of Supersymmetric Dark Matter * Bounds on ΔB = 1 Couplings in the Supersymmetric Standard Model * Testing Supersymmetry at the Next Linear Collider * SUSY Phenomenology II * Is There a Light Gluino Window? * Soft Supersymmetry Breaking and Finiteness * Consequences of Low Energy Dynamical Supersymmetry Breaking * String Model Theory and Phenomenology * Z2 × Z2 Orbifold Compactification - the Origin of Realistic Free Fermionic Models * Effective Supergravity from 4-D Fermionic Strings * String Models Featuring Direct Product Unification * Hadronic and Non-Perturbative Physics * Salient Features of High-Energy Multiparticle Distributions: 1-d Ising Model Captures Them All * Pion Fusion in the Equivalent Pion Approximation * Deterministic Theory of Atomic Structure * Disoriented Chiral Condensate * Higgs Physics * The LHC Phenomenology of the CP-Odd Scalar in Two-Doublet Models * Detection of Minimal Supersymmetric Model Higgs Bosons in γγ Collisions: Influence of SUSY Decay Modes * Electroweak Corrections to the Charged Higgs Production Cross-Section * A Comparison of Higgs Mass Bounds in the SM and the MSSM * Searching for Higgs Bosons on LHC Using b-Tagging * Top Quark and Flavor Physics * Flavor Mixing, CP Violation and a Heavy Top * New Fermion Families and Precision Electroweak Data * Dipole Operator Phenomenology and Quark Mass Generation: An Update * Possible Higgs Boson Effects on the Running of Third and Fourth Generation Quark Masses and Mixings * How the Top Family Differs * Fermion Masses in Extended Technicolour * New Developments in Perturbative QCD * Efficient Analytic Computation of Higher-Order QCD Amplitudes * Use of Recursion Relations to Compute One-Loop Helicity Amplitudes * Gluon Radiation Patterns in Hard Scattering Events * B Physics * Inclusive Hadronic Production of the Bc Meson via Heavy Quark Fragmentation * Helicity Probabilities for Heavy Quark Fragmentation into Heavy-Light Excited Mesons * Hadronic Penguins in B Decays and Extraction of α, β and γ * CP Violation Physics * Maximum Likelihood Method for New Physics Mixing Angles, and Projections to Using B Factory Results * CP Violation in Fermionic Decays of Higgs Bosons * Test of CP Violation in Non-Leptonic Hyperon Decays * CP Violation in the Weinberg Multi-Higgs Model * Triple-Product Spin-Momentum Correlations in Polarized Z Decays to Three Jets * Radiative CP Violation * HERA Results * A Search for Leptoquarks and Squarks in H1 at HERA * Search for Leptoquarks in ep Collisions at √ {s}=296; {GeV} * Search for Excited Fermions in ep Collisions at √ {s}=296; {GeV} * Tevatron Results * Measurement of Diboson Production at the Tevatron Collider with D0 * Search for SUSY in D0 * Search for SUSY at CDF * Search for First and Second Generation Leptoquarks with the D0 Detector * Search for Exotic Particles at CDF * e+e- and μ+μ- Physics * Aspects of Higgs Boson Searches * Measurements of the Forward-Backward Asymmetry of Quarks in the DELPHI Experiment at LEP * Astrophysics, Dark Matter, Cosmology and Neutrino Physics * A Model Independent Approach to Future Solar Neutrino Experiments * Neutrino Oscillations with Beams from AGN's and GRB's * Implication of Macho Detections for Dark Matter Searches * Chiral Restoration in the Early Universe: Pion Halo in the Sky * SEWS, Anomalous Couplings, and Precision EW * Do WL and H form a P-Wave Bound State? * An Update on Strong WLWL Scattering at the LHC * The Difficulties Involved in Calculating δρ * What Can We Learn from the Measurement R_{b}≡Γ(Z → bbar{b}/Γ(Z → Hadrons)? * Gauge Invariance and Anomalous Gauge Boson Couplings * Probing the Standard Model with Hadronic WZ Production * Consequences of Recent Electroweak Data and W-Mass for the Top Quark and Higgs Masses * Equivalence Theorem as a Criterion for Probing the Electroweak Symmetry Breaking Mechanism * Conference Schedule * Schedule of the Parallel Sessions * List of Participants

The massive fermion phase for the U(N) Chern-Simons gauge theory in D=3 at large N

DOE PAGES

Bardeen, William A.

2014-10-07

We explore the phase structure of fermions in the U(N) Chern-Simons Gauge theory in three dimensions using the large N limit where N is the number of colors and the fermions are taken to be in the fundamental representation of the U(N) gauge group. In the large N limit, the theory retains its classical conformal behavior and considerable attention has been paid to possible AdS/CFT dualities of the theory in the conformal phase. In this paper we present a solution for the massive phase of the fermion theory that is exact to the leading order of ‘t Hooft’s large Nmore » expansion. We present evidence for the spontaneous breaking of the exact scale symmetry and analyze the properties of the dilaton that appears as the Goldstone boson of scale symmetry breaking.« less

Whiteheadian Actual Entitities and String Theory

NASA Astrophysics Data System (ADS)

Bracken, Joseph A.

2012-06-01

In the philosophy of Alfred North Whitehead, the ultimate units of reality are actual entities, momentary self-constituting subjects of experience which are too small to be sensibly perceived. Their combination into "societies" with a "common element of form" produces the organisms and inanimate things of ordinary sense experience. According to the proponents of string theory, tiny vibrating strings are the ultimate constituents of physical reality which in harmonious combination yield perceptible entities at the macroscopic level of physical reality. Given that the number of Whiteheadian actual entities and of individual strings within string theory are beyond reckoning at any given moment, could they be two ways to describe the same non-verifiable foundational reality? For example, if one could establish that the "superject" or objective pattern of self- constitution of an actual entity vibrates at a specific frequency, its affinity with the individual strings of string theory would be striking. Likewise, if one were to claim that the size and complexity of Whiteheadian 'societies" require different space-time parameters for the dynamic interrelationship of constituent actual entities, would that at least partially account for the assumption of 10 or even 26 instead of just 3 dimensions within string theory? The overall conclusion of this article is that, if a suitably revised understanding of Whiteheadian metaphysics were seen as compatible with the philosophical implications of string theory, their combination into a single world view would strengthen the plausibility of both schemes taken separately. Key words: actual entities, subject/superjects, vibrating strings, structured fields of activity, multi-dimensional physical reality.

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 Higgs, or techni-dilaton - composite Higgs near conformality / Koichi Yamawaki -- Phase diagram of strongly interacting theories / Francesco Sannino -- Resizing conformal windows / O. Antipin and K. Tuominen -- Nearly conformal gauge theories on the lattice / Zoltan Fodor ... [et al.] -- Going beyond QCD in lattice gauge theory / G. T. Fleming -- Phases of QCD from small to large N[symbol]: (some) lattice results / A. Deuzeman, E. Pallante and M. P. Lombardo -- Lattice gauge theory and (quasi)-conformal technicolor / D. K. Sinclair and J. B. Kogut -- Study of the running coupling constant in 10-flavor QCD with the Schrodinger functional method / N. Yamada ... [et al.] -- Study of the running coupling in twisted Polyakov scheme / T. Aoyama ... [et al.].Running coupling in strong gauge theories via the lattice / Zoltan Fodor ... [et al.] -- Higgsinoless supersymmetry and hidden gravity / Michael L. Graesser, Ryuichiro Kitano and Masafumi Kurachi -- The latest status of LHC and the EWSB physics / S. Asai -- Continuum superpartners from supersymmetric unparticles / Hsin-Chia Cheng -- Review of minimal flavor constraints for technicolor / Hidenori S. Fukano and Francesco Sannino -- Standard model and high energy Lorentz violation / Damiano Anselmi -- Dynamical electroweak symmetry breaking and fourth family / Michio Hashimoto -- Holmorphic supersymmetric Nambu-Jona-Lasino model and dynamical electroweak symmetry breaking / Dong-Won Jung, Otto C. W. Kong and Jae Sik Lee -- Ratchet model of Baryogenesis / Tatsu Takeuchi, Azusa Minamizaki and Akio Sugamoto -- Classical solutions of field equations in Einstein Gauss-Bonnet gravity / P. Suranyi, C. Vaz and L. C. R. Wijewardhana -- Black holes constitute all dark matter / Paul H. Frampton -- Electroweak precision test and Z [symbol] in the three site Higgsless model / Tomohiro Abe -- Chiral symmetry and BRST symmetry breaking, quaternion reality and the lattice simulation / Sadataka Furui -- Holographic techni-dilaton, or conformal Higgs / Kazumoto Haba, Shinya Matsuzaki and Koichi Yamawaki -- Phase structure of topologically massive gauge theory with fermion / Yuichi Hoshino -- New regularization in extra dimensional model and renormalization group flow of the cosmological constant / Shoichi Ichinose -- Spectral analysis of dense two-color QCD / T. Kanazawa, T. Wettig and N. Yamamoto -- NJL model with dimensional regularization at finite temperature / T. Fujihara ... [et al.] -- A new method of evaluating the dynamical chiral symmetry breaking scale and the chiral restoration temperature in general gauge theories by using the non-perturbative renormalization group analyses with general 4-Fermi effective interaction space / Ken-Ichi Aoki, Daisuke Sato and Kazuhiro Miyashita -- The effective chiral Lagrangian with vector mesons and hadronic [symbol] decays / D. Kimura ... [et al.] -- Spontaneous SUSY breaking with anomalous U(1) symmetry in metastable vacua and moduli stabilization / Hiroyuki Nishino -- A new description of the lattice Yang-Mills theory and non-abelian magnetic monopole dominance in the string tension / Akihiro Shibata -- Thermodynamics with unbroken center symmetry in two-flavor QCD / S. Takemoto, M. Harada and C. Sasaki -- Masses of vector bosons in two-color QCD based on the hidden local symmetry / T. Yamaoka, M. Harada and C. Nonaka -- Walking dynamics from string duals / Maurizio Piai -- The quark mass dependence of the nucleon mass in AdS/QCD / Hyo Chul Ahn -- Structure of thermal quasi-fermion in QED/QCD from the Dyson-Schwinger equation / Hisao Nakkagawa -- Critical behaviors of sigma-mode and pion in holographic superconductors / Cheonsoo Park.

String Theory, the Crisis in Particle Physics and the Ascent of Metaphoric Arguments

NASA Astrophysics Data System (ADS)

Schroer, Bert

This essay presents a critical evaluation of the concepts of string theory and its impact on particle physics. The point of departure is a historical review of four decades of string theory within the broader context of six decades of failed attempts at an autonomous S matrix approach to particle theory. The central message, contained in Secs. 5 and 6, is that string theory is not what its name suggests, namely a theory of objects in space-time whose localization is string-instead of pointlike. Contrary to popular opinion, the oscillators corresponding to the Fourier models of a quantum-mechanical string do not become embedded in space-time and neither does the "range space" of a chiral conformal QFT acquire the interpretation of stringlike-localized quantum matter. Rather, string theory represents a solution to a problem which enjoyed some popularity in the 1960s: find a principle which, similar to the SO(4,2) group in the case of the hydrogen spectrum, determines an infinite component wave function with a (realistic) mass/spin spectrum. Instead of the group theory used in the old failed attempts, it creates this mass/spin spectrum by combining an internal oscillator quantum mechanics with a pointlike-localized quantum-field-theoretic object, i.e. the mass/spin tower "sits" over one point and does not arise from a wiggling string in space-time. The widespread acceptance of a theory whose interpretation has been based on metaphoric reasoning had a corroding influence on particle theory, a point which will be illustrated in the last section with some remarks of a more sociological nature. These remarks also lend additional support to observations on connections between the discourse in particle physics and the present Zeitgeist of the post-Cold War period that are made in the introduction.

Five-dimensional fermionic Chern-Simons theory

NASA Astrophysics Data System (ADS)

Bak, Dongsu; Gustavsson, Andreas

2018-02-01

We study 5d fermionic CS theory with a fermionic 2-form gauge potential. This theory can be obtained from 5d maximally supersymmetric YM theory by performing the maximal topological twist. We put the theory on a five-manifold and compute the partition function. We find that it is a topological quantity, which involves the Ray-Singer torsion of the five-manifold. For abelian gauge group we consider the uplift to the 6d theory and find a mismatch between the 5d partition function and the 6d index, due to the nontrivial dimensional reduction of a selfdual two-form gauge field on a circle. We also discuss an application of the 5d theory to generalized knots made of 2d sheets embedded in 5d.

Rooting issue for a lattice fermion formulation similar to staggered fermions but without taste mixing

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

Adams, David H.

2008-05-15

To investigate the viability of the 4th root trick for the staggered fermion determinant in a simpler setting, we consider a 2-taste (flavor) lattice fermion formulation with no taste mixing but with exact taste-nonsinglet chiral symmetries analogous to the taste-nonsinglet U(1){sub A} symmetry of staggered fermions. Creutz's objections to the rooting trick apply just as much in this setting. To counter them we show that the formulation has robust would-be zero modes in topologically nontrivial gauge backgrounds, and that these manifest themselves in a viable way in the rooted fermion determinant and also in the disconnected piece of the pseudoscalarmore » meson propagator as required to solve the U(1) problem. Also, our rooted theory is heuristically seen to be in the right universality class for QCD if the same is true for an unrooted mixed fermion action theory.« less

Two-dimensional conductors with interactions and disorder from particle-vortex duality

NASA Astrophysics Data System (ADS)

Goldman, H.; Mulligan, M.; Raghu, S.; Torroba, G.; Zimet, M.

2017-12-01

We study Dirac fermions in two spatial dimensions (2D) coupled to strongly fluctuating U (1 ) gauge fields in the presence of quenched disorder. Such systems are dual to theories of free Dirac fermions, which are vortices of the original theory. In analogy to superconductivity, when these fermionic vortices localize, the original system becomes a perfect conductor, and when the vortices possess a finite conductivity, the original fermions do as well. We provide several realizations of this principle and thereby introduce examples of strongly interacting 2D metals that evade Anderson localization.

Cosmic superstrings: Observable remnants of brane inflation

NASA Astrophysics Data System (ADS)

Wyman, Mark Charles

Brane inflation provides a natural dynamical model for the physics which underlie the inflationary paradigm. Besides their inflationary predictions, brane models imply another observable consequence: cosmic strings. In this dissertation I outline the background of how cosmic strings arise in brane inflationary models and how the properties of the strings and the models are mutually tied (Chapter 2). I then use cosmological observations to put limits on the properties of any actually-existing cosmic string network (Chapter 3). Next, I study the question of how cosmic superstrings, as the cosmic strings arising from string theory are known, could be distinct from classical gauge- theory cosmic strings. In particular, I propose an analytical model for the cosmological evolution of a network of binding cosmic strings (Chapter 4); I also describe the distinctive gravitational lensing phenomena that are caused by binding strings (Chapter 5). Finally, I lay out the background for the numerical study of a gauge theory model for the dynamics of cosmic superstring binding (Chapter 6).

On the gauge chosen by the bosonic open string

NASA Astrophysics Data System (ADS)

Pesando, Igor

2017-05-01

String theory gives S matrix elements from which is not possible to read any gauge information. Using factorization we go off shell in the simplest and most naive way and we read which are the vertices suggested by string. To compare with the associated Effective Field Theory it is natural to use color ordered vertices. The α‧ = 0 color ordered vertices suggested by string theory are more efficient than the usual ones since the three gluon color ordered vertex has three terms instead of six and the four gluon one has one term instead of three. They are written in the so called Gervais-Neveu gauge. The full Effective Field Theory is in a generalization of the Gervais-Neveu gauge with α‧ corrections. Moreover a field redefinition is required to be mapped to the field used by string theory. We also give an intuitive way of understanding why string choose this gauge in terms of the minimal number of couplings necessary to reproduce the non-abelian amplitudes starting from color ordered ones.

Classical probes of string/gauge theory duality

NASA Astrophysics Data System (ADS)

Ishizeki, Riei

The AdS/CFT correspondence has played an important role in the recent development of string theory. The reason is that it proposes a description of certain gauge theories in terms of string theory. It is such that simple string theory computations give information about the strong coupling regime of the gauge theory. Vice versa, gauge theory computations give information about string theory and quantum gravity. Although much is known about AdS/CFT, the precise map between the two sides of the correspondence is not completely understood. In the unraveling of such map classical string solutions play a vital role. In this thesis, several classical string solutions are proposed to help understand the AdS/CFT duality. First, rigidly rotating strings on a two-sphere are studied. Taking special limits of such solutions leads to two cases: the already known giant magnon solution, and a new solution which we call the single spike solution. Next, we compute the scattering phase shift of the single spike solutions and compare the result with the giant magnon solutions. Intriguingly, the results are the same up to non-logarithmic terms, indicating that the single spike solution should have the same rich spin chain structure as the giant magnon solution. Afterward, we consider open string solutions ending on the boundary of AdS5. The lines traced by the ends of such open strings can be viewed as Wilson loops in N = 4 SYM theory. After applying an inversion transformation, the open Wilson loops become closed Wilson loops whose expectation value is consistent with previously conjectured results. Next, several Wilson loops for N = 4 SYM in an AdS5 pp-wave background are considered and translated to the pure AdS 5 background and their interpretation as forward quark-gluon scattering is suggested. In the last part of this thesis, a class of classical solutions for closed strings moving in AdS3 x S 1 ⊂ AdS5 x S5 with energy E and spin S in AdS3 and angular momentum J and winding m in S1 is explained. The relation between different limits of the spiky string solution with the Landau-Lifshitz model is of particular interest. The presented solutions provide new classes of string motion that are used to better understand the AdS/CFT correspondence, including the single spike solution and previously unknown examples of supersymmetric Wilson loops.

Julius Edgar Lilienfeld Prize Lecture: The Higgs Boson, String Theory, and the Real World

NASA Astrophysics Data System (ADS)

Kane, Gordon

2012-03-01

In this talk I'll describe how string theory is exciting because it can address most, perhaps all, of the questions we hope to understand about our world: why quarks and leptons make up our world, what forces form our world, cosmology, parity violation, and much more. I'll explain why string theory is testable in basically the same ways as the rest of physics, and why much of what is written about that is misleading. String theory is already or soon being tested in several ways, including correctly predicting the recently observed Higgs boson properties and mass, and predictions for dark matter, LHC physics, cosmological history, and more, from work in the increasingly active subfield ``string phenomenology.''

Factorization of chiral string amplitudes

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

Huang, Yu-tin; Siegel, Warren; Yuan, Ellis Ye

We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: as found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to bemore » auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.« less

Factorization of chiral string amplitudes

DOE PAGES

Huang, Yu-tin; Siegel, Warren; Yuan, Ellis Ye

2016-09-16

We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: as found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to bemore » auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.« less

Ghost vertices for the bosonic string using the group-theoretic approach to string theory

NASA Astrophysics Data System (ADS)

Freeman, M. D.; West, P.

1988-04-01

The N-string tree-level scattering vertices for the bosonic string are extended to include anticommuting (ghost) oscillators. These vertices behave correctly under the action of the BRST charge Q and reproduce the known results for the scattering of physical states. This work is an application of the group-theoretic approach to string theory. Permanent address: Mathematics Department, King's College, Strand, London WC2R 2LS, UK.

Abelian gauge symmetries in F-theory and dual theories

NASA Astrophysics Data System (ADS)

Song, Peng

In this dissertation, we focus on important physical and mathematical aspects, especially abelian gauge symmetries, of F-theory compactifications and its dual formulations within type IIB and heterotic string theory. F-theory is a non-perturbative formulation of type IIB string theory which enjoys important dualities with other string theories such as M-theory and E8 x E8 heterotic string theory. One of the main strengths of F-theory is its geometrization of many physical problems in the dual string theories. In particular, its study requires a lot of mathematical tools such as advanced techniques in algebraic geometry. Thus, it has also received a lot of interests among mathematicians, and is a vivid area of research within both the physics and the mathematics community. Although F-theory has been a long-standing theory, abelian gauge symmetry in Ftheory has been rarely studied, until recently. Within the mathematics community, in 2009, Grassi and Perduca first discovered the possibility of constructing elliptically fibered varieties with non-trivial toric Mordell-Weil group. In the physics community, in 2012, Morrison and Park first made a major advancement by constructing general F-theory compactifications with U(1) abelian gauge symmetry. They found that in such cases, the elliptically-fibered Calabi-Yau manifold that F-theory needs to be compactified on has its fiber being a generic elliptic curve in the blow-up of the weighted projective space P(1;1;2) at one point. Subsequent developments have been made by Cvetic, Klevers and Piragua extended the works of Morrison and Park and constructed general F-theory compactifications with U(1) x U(1) abelian gauge symmetry. They found that in the U(1) x U(1) abelian gauge symmetry case, the elliptically-fibered Calabi-Yau manifold that F-theory needs to be compactified on has its fiber being a generic elliptic curve in the del Pezzo surface dP2. In chapter 2 of this dissertation, I bring this a step further by constructing general F-theory compactifications with U(1) x U(1) x U(1) abelian gauge symmetry. In chapter 1 of this dissertation, I proved finiteness of a region of the string landscape in Type IIB compactifications. String compactifications give rise to a collection of effective low energy theories, known as the string landscape. In chapter 3 of this dissertation, I study abelian gauge symmetries in the duality between F-theory and E8 x E8 heterotic string theory. However, how abelian gauge symmetries can arise in the dual heterotic string theory has never been studied. The main goal of this chapter is to study exactly this. We start with F-theory compactifications with abelian gauge symmetry. With the help of a mathematical lemma as well as a computer code that I came up with, I was able to construct a rich list of specialized examples with specific abelian and nonabelian gauge groups on the F-theory side. (Abstract shortened by ProQuest.).

The role of heuristic appraisal in conflicting assessments of string theory

NASA Astrophysics Data System (ADS)

Camilleri, Kristian; Ritson, Sophie

2015-08-01

Over the last three decades, string theory has emerged as one of the leading hopes for a consistent theory of quantum gravity that unifies particle physics with general relativity. Despite the fact that string theory has been a thriving research program for the better part of three decades, it has been subjected to extensive criticism from a number of prominent physicists. The aim of this paper is to obtain a clearer picture of where the conflict lies in competing assessments of string theory, through a close reading of the argumentative strategies employed by protagonists on both sides. Although it has become commonplace to construe this debate as stemming from different attitudes to the absence of testable predictions, we argue that this presents an overly simplified view of the controversy, which ignores the critical role of heuristic appraisal. While string theorists and their defenders see the theoretical achievements of the string theory program as providing strong indication that it is 'on the right track', critics have challenged such claims, by calling into question the status of certain 'solved problems' and its purported 'explanatory coherence'. The debates over string theory are therefore particularly instructive from a philosophical point of view, not only because they offer important insights into the nature of heuristic appraisal and theoretical progress, but also because they raise deep questions about what constitutes a solved problem and an explanation in fundamental physics.

Deconfinement and the Hagedorn transition in string theory.

PubMed

Chaudhuri, S

2001-03-05

We introduce a new definition of the thermal partition function in string theory. With this new definition, the thermal partition functions of all of the string theories obey thermal duality relations with self-dual Hagedorn temperature beta(2)(H) = 4pi(2)alpha('). A beta-->beta(2)(H)/beta transformation maps the type I theory into a new string theory (type I) with thermal D p-branes, spatial hypersurfaces supporting a p-dimensional finite temperature non-Abelian Higgs-gauge theory for p< or =9. We demonstrate a continuous phase transition in the behavior of the static heavy quark-antiquark potential for small separations r(2)(*)

Scattering of fermions in the Yukawa theory coupled to unimodular gravity

NASA Astrophysics Data System (ADS)

Gonzalez-Martin, S.; Martin, C. P.

2018-03-01

We compute the lowest order gravitational UV divergent radiative corrections to the S matrix element of the fermion + fermion→ fermion + fermion scattering process in the massive Yukawa theory, coupled either to Unimodular Gravity or to General Relativity. We show that both Unimodular Gravity and General Relativity give rise to the same UV divergent contribution in Dimensional Regularization. This is a nontrivial result, since in the classical action of Unimodular Gravity coupled to the Yukawa theory, the graviton field does not couple neither to the mass operator nor to the Yukawa operator. This is unlike the General Relativity case. The agreement found points in the direction that Unimodular Gravity and General Relativity give rise to the same quantum theory when coupled to matter, as long as the Cosmological Constant vanishes. Along the way we have come across another unexpected cancellation of UV divergences for both Unimodular Gravity and General Relativity, resulting in the UV finiteness of the one-loop and κ y^2 order of the vertex involving two fermions and one graviton only.

Two-dimensional conductors with interactions and disorder from particle-vortex duality

DOE PAGES

Goldman, H.; Mulligan, M.; Raghu, S.; ...

2017-12-27

Here, we study Dirac fermions in two spatial dimensions (2D) coupled to strongly fluctuating U(1) gauge fields in the presence of quenched disorder. Such systems are dual to theories of free Dirac fermions, which are vortices of the original theory. In analogy to superconductivity, when these fermionic vortices localize, the original system becomes a perfect conductor, and when the vortices possess a finite conductivity, the original fermions do as well. We provide several realizations of this principle and thereby introduce examples of strongly interacting 2D metals that evade Anderson localization.

Two-dimensional conductors with interactions and disorder from particle-vortex duality

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

Goldman, H.; Mulligan, M.; Raghu, S.

Here, we study Dirac fermions in two spatial dimensions (2D) coupled to strongly fluctuating U(1) gauge fields in the presence of quenched disorder. Such systems are dual to theories of free Dirac fermions, which are vortices of the original theory. In analogy to superconductivity, when these fermionic vortices localize, the original system becomes a perfect conductor, and when the vortices possess a finite conductivity, the original fermions do as well. We provide several realizations of this principle and thereby introduce examples of strongly interacting 2D metals that evade Anderson localization.

Fermion bag approach to Hamiltonian lattice field theories in continuous time

NASA Astrophysics Data System (ADS)

Huffman, Emilie; Chandrasekharan, Shailesh

2017-12-01

We extend the idea of fermion bags to Hamiltonian lattice field theories in the continuous time formulation. Using a class of models we argue that the temperature is a parameter that splits the fermion dynamics into small spatial regions that can be used to identify fermion bags. Using this idea we construct a continuous time quantum Monte Carlo algorithm and compute critical exponents in the 3 d Ising Gross-Neveu universality class using a single flavor of massless Hamiltonian staggered fermions. We find η =0.54 (6 ) and ν =0.88 (2 ) using lattices up to N =2304 sites. We argue that even sizes up to N =10 ,000 sites should be accessible with supercomputers available today.

On the Minimal Length Uncertainty Relation and the Foundations of String Theory

DOE PAGES

Chang, Lay Nam; Lewis, Zachary; Minic, Djordje; ...

2011-01-01

We review our work on the minimal length uncertainty relation as suggested by perturbative string theory. We discuss simple phenomenological implications of the minimal length uncertainty relation and then argue that the combination of the principles of quantum theory and general relativity allow for a dynamical energy-momentum space. We discuss the implication of this for the problem of vacuum energy and the foundations of nonperturbative string theory.

Solvability of a Nonlinear Integral Equation in Dynamical String Theory

NASA Astrophysics Data System (ADS)

Khachatryan, A. Kh.; Khachatryan, Kh. A.

2018-04-01

We investigate an integral equation of the convolution type with a cubic nonlinearity on the entire real line. This equation has a direct application in open-string field theory and in p-adic string theory and describes nonlocal interactions. We prove that there exists a one-parameter family of bounded monotonic solutions and calculate the limits of solutions constructed at infinity.

Matrix theory interpretation of discrete light cone quantization string worldsheets

PubMed

Grignani; Orland; Paniak; Semenoff

2000-10-16

We study the null compactification of type-IIA string perturbation theory at finite temperature. We prove a theorem about Riemann surfaces establishing that the moduli spaces of infinite-momentum-frame superstring worldsheets are identical to those of branched-cover instantons in the matrix-string model conjectured to describe M theory. This means that the identification of string degrees of freedom in the matrix model proposed by Dijkgraaf, Verlinde, and Verlinde is correct and that its natural generalization produces the moduli space of Riemann surfaces at all orders in the genus expansion.

Geometry, topology, and string theory

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

Varadarajan, Uday

A variety of scenarios are considered which shed light upon the uses and limitations of classical geometric and topological notions in string theory. The primary focus is on situations in which D-brane or string probes of a given classical space-time see the geometry quite differently than one might naively expect. In particular, situations in which extra dimensions, non-commutative geometries as well as other non-local structures emerge are explored in detail. Further, a preliminary exploration of such issues in Lorentzian space-times with non-trivial causal structures within string theory is initiated.

Perturbation theory from automorphic forms

NASA Astrophysics Data System (ADS)

Lambert, Neil; West, Peter

2010-05-01

Using our previous construction of Eisenstein-like automorphic forms we derive formulae for the perturbative and non-perturbative parts for any group and representation. The result is written in terms of the weights of the representation and the derivation is largely group theoretical. Specialising to the E n+1 groups relevant to type II string theory and the representation associated with node n + 1 of the E n+1 Dynkin diagram we explicitly find the perturbative part in terms of String Theory variables, such as the string coupling g d and volume V n . For dimensions seven and higher we find that the perturbation theory involves only two terms. In six dimensions we construct the SO(5, 5) automorphic form using the vector representation. Although these automorphic forms are generally compatible with String Theory, the one relevant to R 4 involves terms with g d -6 and so is problematic. We then study a constrained SO(5, 5) automorphic form, obtained by summing over null vectors, and compute its perturbative part. We find that it is consistent with String Theory and makes precise predictions for the perturbative results. We also study the unconstrained automorphic forms for E 6 in the 27 representation and E 7 in the 133 representation, giving their perturbative part and commenting on their role in String Theory.

Strings on plane-waves and spin chains on orbifolds

NASA Astrophysics Data System (ADS)

Sadri, Darius

This thesis covers a number of topics in string theory focusing on various aspects of the AdS/CFT duality in various guises and regimes. In the first chapter we present a self-contained review of the Plane-wave/super-Yang-Mills duality. This duality is a specification of the usual AdS/CFT correspondence in the "Penrose limit". In chapter two we study the most general parallelizable pp-wave backgrounds which are non-dilatonic solutions in the NS-NS sector of type IIA and IIB string theories. We demonstrate that parallelizable pp-wave backgrounds are necessarily homogeneous plane-waves, and that a large class of homogeneous plane-waves are parallelizable, stating the necessary conditions. Quantization of string modes, their compactification and behaviour under T-duality are also studied, as are BPS Dp-branes on such backgrounds. In chapter three we consider giant gravitons on the maximally supersymmetric plane-wave background. We deduce the low energy effective light-cone Hamiltonian of the three-sphere giant graviton, and place sources in this effective gauge theory. Although non-vanishing net electric charge configurations are disallowed by Gauss' law, electric dipoles can be formed. From the string theory point of view these dipoles can be understood as open strings piercing the three-sphere, giving a two dimensional (worldsheet) description of giant gravitons. Chapter four presents some new ideas regarding the relation between super-conformal gauge theories and string theories with three-dimensional target spaces, possible relations of these systems to Hamiltonian lattice gauge theories, and integrable spin chains. We consider N = 1, D = 4 superconformal SU( N)px q Yang-Mills theories dual to AdS5 x S5/Zp x Zq orbifolds. We show that a specific sector of this dilatation operator can be thought of as the transfer matrix for a three-dimensional statistical mechanical system, which in turn is equivalent to a 2 + 1-dimensional string theory where the spatial slices are discretized on a triangular lattice, and comment on the integrability of this N = 1 gauge theory, its connection to three-dimensional lattice gauge theories, extensions to six-dimensional string theories, AdS/CFT type dualities and finally their construction via orbifolds and brane-box models. In the process we discover a new class of almost-BPS BMN type operators with large engineering dimensions but controllably small anomalous corrections.

Instantons in string theory

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

Ahlén, Olof, E-mail: olof.ahlen@aei.mpg.de

2015-12-17

These proceedings from the second Caesar Lattes meeting in Rio de Janeiro 2015 are a brief introduction to how automorphic forms appear in the low energy effective action of maximally supersymmetric string theory. The explicit example of the R{sup 4}-interaction of type IIB string theory in ten dimensions is discussed. Its Fourier expansion is interpreted in terms of perturbative and non-perturbative contributions to the four graviton amplitude.

Hadronic density of states from string theory.

PubMed

Pando Zayas, Leopoldo A; Vaman, Diana

2003-09-12

We present an exact calculation of the finite temperature partition function for the hadronic states corresponding to a Penrose-Güven limit of the Maldacena-Nùñez embedding of the N=1 super Yang-Mills (SYM) into string theory. It is established that the theory exhibits a Hagedorn density of states. We propose a semiclassical string approximation to the finite temperature partition function for confining gauge theories admitting a supergravity dual, by performing an expansion around classical solutions characterized by temporal windings. This semiclassical approximation reveals a hadronic energy density of states of a Hagedorn type, with the coefficient determined by the gauge theory string tension as expected for confining theories. We argue that our proposal captures primarily information about states of pure N=1 SYM theory, given that this semiclassical approximation does not entail a projection onto states of large U(1) charge.

Grassmann phase space methods for fermions. II. Field theory

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

Dalton, B.J., E-mail: bdalton@swin.edu.au; Jeffers, J.; Barnett, S.M.

In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggests the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum-atom optics to treat fermionic systems is rather rare, thoughmore » fermion coherent states using Grassmann variables are widely used in particle physics. This paper presents a phase space theory for fermion systems based on distribution functionals, which replace the density operator and involve Grassmann fields representing anti-commuting fermion field annihilation, creation operators. It is an extension of a previous phase space theory paper for fermions (Paper I) based on separate modes, in which the density operator is replaced by a distribution function depending on Grassmann phase space variables which represent the mode annihilation and creation operators. This further development of the theory is important for the situation when large numbers of fermions are involved, resulting in too many modes to treat separately. Here Grassmann fields, distribution functionals, functional Fokker–Planck equations and Ito stochastic field equations are involved. Typical applications to a trapped Fermi gas of interacting spin 1/2 fermionic atoms and to multi-component Fermi gases with non-zero range interactions are presented, showing that the Ito stochastic field equations are local in these cases. For the spin 1/2 case we also show how simple solutions can be obtained both for the untrapped case and for an optical lattice trapping potential.« less

Unitarity violation in noninteger dimensional Gross-Neveu-Yukawa model

NASA Astrophysics Data System (ADS)

Ji, Yao; Kelly, Michael

2018-05-01

We construct an explicit example of unitarity violation in fermionic quantum field theories in noninteger dimensions. We study the two-point correlation function of four-fermion operators. We compute the one-loop anomalous dimensions of these operators in the Gross-Neveu-Yukawa model. We find that at one-loop order, the four-fermion operators split into three classes with one class having negative norms. This implies that the theory violates unitarity, following the definition in Ref. [1].

Double field theory at order α'

NASA Astrophysics Data System (ADS)

Hohm, Olaf; Zwiebach, Barton

2014-11-01

We investigate α' corrections of bosonic strings in the framework of double field theory. The previously introduced "doubled α'-geometry" gives α'-deformed gauge transformations arising in the Green-Schwarz anomaly cancellation mechanism but does not apply to bosonic strings. These require a different deformation of the duality-covariantized Courant bracket which governs the gauge structure. This is revealed by examining the α' corrections in the gauge algebra of closed string field theory. We construct a four-derivative cubic double field theory action invariant under the deformed gauge transformations, giving a first glimpse of the gauge principle underlying bosonic string α' corrections. The usual metric and b-field are related to the duality covariant fields by non-covariant field redefinitions.

Tensor modes on the string theory landscape

NASA Astrophysics Data System (ADS)

Westphal, Alexander

2013-04-01

We attempt an estimate for the distribution of the tensor mode fraction r over the landscape of vacua in string theory. The dynamics of eternal inflation and quantum tunneling lead to a kind of democracy on the landscape, providing no bias towards large-field or small-field inflation regardless of the class of measure. The tensor mode fraction then follows the number frequency distributions of inflationary mechanisms of string theory over the landscape. We show that an estimate of the relative number frequencies for small-field vs large-field inflation, while unattainable on the whole landscape, may be within reach as a regional answer for warped Calabi-Yau flux compactifications of type IIB string theory.

Notes on strings and higher spins

NASA Astrophysics Data System (ADS)

Sagnotti, A.

2013-05-01

This review is devoted to the intriguing and still largely unexplored links between string theory and higher spins, the types of excitations that lie behind their most cherished properties. A closer look at higher spin fields provides some further clues that string theory describes a broken phase of a higher spin gauge theory. Conversely, string amplitudes contain a wealth of information on higher spin interactions that can clarify long-standing issues related to their infrared behavior. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Higher spin theories and holography’. Based on the lectures presented at the International School for Subnuclear Physics Searching for the Unexpected at LHC and Status of Our Knowledge (Erice, June 24-July 3 2011) and on the talks presented at Strings, Branes and Supergravity (Istanbul, 31 July -5 Aug 2011), at QTS’07: Quantum Theory and Symmetries (Prague, 7-13 Aug. 2011) and at FFP’12: Fundamental Fields and Particles (Udine, 21-23 Nov. 2011).

String duality transformations in f(R) gravity from Noether symmetry approach

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

Capozziello, Salvatore; Gionti, Gabriele S.J.; Vernieri, Daniele, E-mail: capozziello@na.inf.it, E-mail: ggionti@as.arizona.edu, E-mail: vernieri@iap.fr

2016-01-01

We select f(R) gravity models that undergo scale factor duality transformations. As a starting point, we consider the tree-level effective gravitational action of bosonic String Theory coupled with the dilaton field. This theory inherits the Busher's duality of its parent String Theory. Using conformal transformations of the metric tensor, it is possible to map the tree-level dilaton-graviton string effective action into f(R) gravity, relating the dilaton field to the Ricci scalar curvature. Furthermore, the duality can be framed under the standard of Noether symmetries and exact cosmological solutions are derived. Using suitable changes of variables, the string-based f(R) Lagrangians aremore » shown in cases where the duality transformation becomes a parity inversion.« less

Note on tachyon moduli and closed strings

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

Carneiro da Cunha, Bruno

2008-07-15

The collective behavior of the SL(2,R) covariant brane states of noncritical c=1 string theory, found in a previous work, is studied in the Fermi liquid approximation. It is found that such states mimic the coset WZW model, whereas only by further restrictions one recovers the double-scaling limit which was purported to be equivalent to closed string models. Another limit is proposed, inspired by the tachyon condensation ideas, where the spectrum is the same of two-dimensional string theory. We close by noting some strange connections between vacuum states of the theory in their different interpretations.

Quark-antiquark potential in defect conformal field theory

NASA Astrophysics Data System (ADS)

Preti, Michelangelo; Trancanelli, Diego; Vescovi, Edoardo

2017-10-01

We consider antiparallel Wilson lines in N = 4 super Yang-Mills in the presence of a codimension-1 defect. We compute the Wilson lines' expectation value both at weak coupling, in the gauge theory, and at strong coupling, by finding the string configurations which are dual to this operator. These configurations display a Gross-Ooguri transition between a connected, U-shaped string phase and a phase in which the string breaks into two disconnected surfaces. We analyze in detail the critical configurations separating the two phases and compare the string result with the gauge theory one in a certain double scaling limit.

Strong coupling in F-theory and geometrically non-Higgsable seven-branes

NASA Astrophysics Data System (ADS)

Halverson, James

2017-06-01

Geometrically non-Higgsable seven-branes carry gauge sectors that cannot be broken by complex structure deformation, and there is growing evidence that such configurations are typical in F-theory. We study strongly coupled physics associated with these branes. Axiodilaton profiles are computed using Ramanujan's theories of elliptic functions to alternative bases, showing explicitly that the string coupling is O (1) in the vicinity of the brane; that it sources nilpotent SL (2 , Z) monodromy and therefore the associated brane charges are modular; and that essentially all F-theory compactifications have regions with order one string coupling. It is shown that non-perturbative SU (3) and SU (2) seven-branes are related to weakly coupled counterparts with D7-branes via deformation-induced Hanany-Witten moves on (p , q) string junctions that turn them into fundamental open strings; only the former may exist for generic complex structure. D3-brane near these and the Kodaira type II seven-branes probe Argyres-Douglas theories. The BPS states of slightly deformed theories are shown to be dyonic string junctions.

Highly symmetric D-brane-anti-D-brane effective actions

NASA Astrophysics Data System (ADS)

Hatefi, Ehsan

2017-09-01

The entire S-matrix elements of four, five and six point functions of D-brane-anti D-brane system are explored. To deal with symmetries of string amplitudes as well as their all order α ' corrections we first address a four point function of one closed string Ramond-Ramond (RR) and two real tachyons on the world volume of brane-anti brane system. We then focus on symmetries of string theory as well as universal tachyon expansion to achieve both string and effective field theory of an RR and three tachyons where the complete algebraic analysis for the whole S-matrix < {V}_{C^{-1}}{V}_{T^{-1}}{V}_{T^0}{V}_{T^0}> was also revealed. Lastly, we employ all the conformal field theory techniques to < {V}_{C^{-1}}{V}_{T^{-1}}{V}_{T^0}{V}_{T^0}{V}_{T^0}> , working out with symmetries of theory and find out the expansion for the amplitude to be able to precisely discover all order singularity structures of D-brane-anti-D-brane effective actions of string theory. Various remarks about the so called generalized Veneziano amplitude and new string couplings are elaborated as well.

String theory of the Regge intercept.

PubMed

Hellerman, S; Swanson, I

2015-03-20

Using the Polchinski-Strominger effective string theory in the covariant gauge, we compute the mass of a rotating string in D dimensions with large angular momenta J, in one or two planes, in fixed ratio, up to and including first subleading order in the large J expansion. This constitutes a first-principles calculation of the value for the order-J(0) contribution to the mass squared of a meson on the leading Regge trajectory in planar QCD with bosonic quarks. For open strings with Neumann boundary conditions, and for closed strings in D≥5, the order-J(0) term in the mass squared is exactly calculated by the semiclassical approximation. This term in the expansion is universal and independent of the details of the theory, assuming only D-dimensional Poincaré invariance and the absence of other infinite-range excitations on the string world volume, beyond the Nambu-Goldstone bosons.

BOOK REVIEW: String Theory in a Nutshell

NASA Astrophysics Data System (ADS)

Skenderis, Kostas

2007-11-01

The book 'String Theory in a Nutshell' by Elias Kiritsis provides a comprehensive introduction to modern string theory. String theory is the leading candidate for a theory that successfully unifies all fundamental forces of nature, including gravity. The subject has been continuously developing since the early 1970s, with classic textbooks on the subject being those of Green, Schwarz and Witten (1987) and Polchinski (1998). Since the latter was published there have been substantial developments, in particular in understanding black holes and gravity/gauge theory dualities. A textbook treatment of this important material is clearly needed, both by students and researchers in string theory and by mathematicians and physicists working in related fields. This book has a good selection of material, starting from basics and moving into classic and modern topics. In particular, Kiritsis' presentation of the basic material is complementary to that of the earlier textbooks and he includes a number of topics which are not easily found or covered adequately elsewhere, for example, loop corrections to string effective couplings. Overall the book nicely covers the major advances of the last ten years, including (non-perturbative) string dualities, black hole physics, AdS/CFT and matrix models. It provides a concise but fairly complete introduction to these subjects which can be used both by students and by researchers. Moreover the emphasis is on results that are reasonably established, as is appropriate for a textbook; concise summaries are given for subjects which are still in flux, with references to relevant reviews and papers. A positive feature of the book is that the bibliography sections at the end of each chapter provide a comprehensive guide to the literature. The bibliographies point to reviews and pedagogical papers on subjects covered in this book as well as those that were omitted. It is rare for a textbook to contain such a self-contained and detailed guide to the literature. In all, the book contains nearly five hundred exercises for the graduate-level student, which are useful both in teaching courses on string theory and for those who are studying by themselves. A nice feature of this book is that references are made to specific pages earlier in the book, rather than to chapters, which is helpful for students working through the book on their own. In summary,'String Theory in a Nutshell'is a valuable addition to the existing string theory textbooks; it is complementary to the previous books and gives a good treatment of subsequent developments. It is likely to become a staple reference on the subject, used both by students and researchers.

Liquid-gas phase transitions and C K symmetry in quantum field theories

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

Nishimura, Hiromichi; Ogilvie, Michael C.; Pangeni, Kamal

A general field-theoretic framework for the treatment of liquid-gas phase transitions is developed. Starting from a fundamental four-dimensional field theory at nonzero temperature and density, an effective three-dimensional field theory is derived. The effective field theory has a sign problem at finite density. Although finite density explicitly breaks charge conjugation C , there remains a symmetry under C K , where K is complex conjugation. Here, we consider four models: relativistic fermions, nonrelativistic fermions, static fermions and classical particles. The interactions are via an attractive potential due to scalar field exchange and a repulsive potential due to massive vector exchange.more » The field-theoretic representation of the partition function is closely related to the equivalence of the sine-Gordon field theory with a classical gas. The thermodynamic behavior is extracted from C K -symmetric complex saddle points of the effective field theory at tree level. In the cases of nonrelativistic fermions and classical particles, we find complex saddle point solutions but no first-order transitions, and neither model has a ground state at tree level. The relativistic and static fermions show a liquid-gas transition at tree level in the effective field theory. The liquid-gas transition, when it occurs, manifests as a first-order line at low temperature and high density, terminated by a critical end point. The mass matrix controlling the behavior of correlation functions is obtained from fluctuations around the saddle points. Due to the C K symmetry of the models, the eigenvalues of the mass matrix are not always real but can be complex. This then leads to the existence of disorder lines, which mark the boundaries where the eigenvalues go from purely real to complex. The regions where the mass matrix eigenvalues are complex are associated with the critical line. In the case of static fermions, a powerful duality between particles and holes allows for the analytic determination of both the critical line and the disorder lines. Depending on the values of the parameters, either zero, one, or two disorder lines are found. Our numerical results for relativistic fermions give a very similar picture.« less

Liquid-gas phase transitions and C K symmetry in quantum field theories

DOE PAGES

Nishimura, Hiromichi; Ogilvie, Michael C.; Pangeni, Kamal

2017-04-04

A general field-theoretic framework for the treatment of liquid-gas phase transitions is developed. Starting from a fundamental four-dimensional field theory at nonzero temperature and density, an effective three-dimensional field theory is derived. The effective field theory has a sign problem at finite density. Although finite density explicitly breaks charge conjugation C , there remains a symmetry under C K , where K is complex conjugation. Here, we consider four models: relativistic fermions, nonrelativistic fermions, static fermions and classical particles. The interactions are via an attractive potential due to scalar field exchange and a repulsive potential due to massive vector exchange.more » The field-theoretic representation of the partition function is closely related to the equivalence of the sine-Gordon field theory with a classical gas. The thermodynamic behavior is extracted from C K -symmetric complex saddle points of the effective field theory at tree level. In the cases of nonrelativistic fermions and classical particles, we find complex saddle point solutions but no first-order transitions, and neither model has a ground state at tree level. The relativistic and static fermions show a liquid-gas transition at tree level in the effective field theory. The liquid-gas transition, when it occurs, manifests as a first-order line at low temperature and high density, terminated by a critical end point. The mass matrix controlling the behavior of correlation functions is obtained from fluctuations around the saddle points. Due to the C K symmetry of the models, the eigenvalues of the mass matrix are not always real but can be complex. This then leads to the existence of disorder lines, which mark the boundaries where the eigenvalues go from purely real to complex. The regions where the mass matrix eigenvalues are complex are associated with the critical line. In the case of static fermions, a powerful duality between particles and holes allows for the analytic determination of both the critical line and the disorder lines. Depending on the values of the parameters, either zero, one, or two disorder lines are found. Our numerical results for relativistic fermions give a very similar picture.« less

Detection of low tension cosmic superstrings

NASA Astrophysics Data System (ADS)

Chernoff, David F.; Tye, S.-H. Henry

2018-05-01

Cosmic superstrings of string theory differ from conventional cosmic strings of field theory. We review how the physical and cosmological properties of the macroscopic string loops influence experimental searches for these relics from the epoch of inflation. The universe's average density of cosmic superstrings can easily exceed that of conventional cosmic strings having the same tension by two or more orders of magnitude. The cosmological behavior of the remnant superstring loops is qualitatively distinct because the string tension is exponentially smaller than the string scale in flux compactifications in string theory. Low tension superstring loops live longer, experience less recoil (rocket effect from the emission of gravitational radiation) and tend to cluster like dark matter in galaxies. Clustering enhances the string loop density with respect to the cosmological average in collapsed structures in the universe. The enhancement at the Sun's position is ~ 105. We develop a model encapsulating the leading order string theory effects, the current understanding of the string network loop production and the influence of cosmological structure formation suitable for forecasting the detection of superstring loops via optical microlensing, gravitational wave bursts and fast radio bursts. We evaluate the detection rate of bursts from cusps and kinks by LIGO- and LISA-like experiments. Clustering dominates rates for G μ < 10‑11.9 (LIGO cusp), G μ<10‑11.2 (LISA cusp), G μ < 10‑10.6 (LISA kink); we forecast experimentally accessible gravitational wave bursts for G μ>10‑14.2 (LIGO cusp), G μ>10‑15 (LISA cusp) and G μ>10‑ 14.1 (LISA kink).

A Formulation of Quantum Field Theory Realizing a Sea of Interacting Dirac Particles

NASA Astrophysics Data System (ADS)

Finster, Felix

2011-08-01

In this survey article, we explain a few ideas behind the fermionic projector approach and summarize recent results which clarify the connection to quantum field theory. The fermionic projector is introduced, which describes the physical system by a collection of Dirac states, including the states of the Dirac sea. Formulating the interaction by an action principle for the fermionic projector, we obtain a consistent description of interacting quantum fields which reproduces the results of perturbative quantum field theory. We find a new mechanism for the generation of boson masses and obtain small corrections to the field equations which violate causality.

Higher winding strings and confined monopoles in N=2 supersymmetric QCD

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

Auzzi, R.; Bolognesi, S.; Shifman, M.

2010-04-15

We consider composite string solutions in N=2 SQCD with the gauge group U(N), the Fayet-Iliopoulos term {xi}{ne}0 and N (s)quark flavors. These bulk theories support non-Abelian strings and confined monopoles identified with kinks in the two-dimensional world-sheet theory. Similar and more complicated kinks (corresponding to composite confined monopoles) must exist in the world-sheet theories on composite strings. In a bid to detect them we analyze the Hanany-Tong (HT) model, focusing on a particular example of N=2. Unequal quark mass terms in the bulk theory result in the twisted masses in the N=(2,2) HT model. For spatially coinciding 2-strings, we findmore » three distinct minima of potential energy, corresponding to three different 2-strings. Then we find BPS-saturated kinks interpolating between each pair of vacua. Two kinks can be called elementary. They emanate one unit of the magnetic flux and have the same mass as the conventional 't Hooft-Polyakov monopole on the Coulomb branch of the bulk theory ({xi}=0). The third kink represents a composite bimonopole, with twice the minimal magnetic flux. Its mass is twice the mass of the elementary confined monopole. We find instantons in the HT model, and discuss quantum effects in composite strings at strong coupling. In addition, we study the renormalization group flow in this model.« less

Physics from geometry: Non-Kahler compactifications, black rings anddS/CFT

NASA Astrophysics Data System (ADS)

Cyrier, Michelle

The spectrum that arises in four dimensions from compactification of ten dimensional string theory onto six dimensional manifolds is determined entirely by the geometry of the compactification manifold. The massless spectrum for compactifications on Calabi-Yau threefolds, which are Kahler and have complex structure, is well understood. In chapter 2 of this thesis, We study the compactification of heterotic string theory on manifolds that are non-Kahler. Such manifolds arise as a solution for compactifications of heterotic string theory with nonzero H-flux. We begin the study of the massless spectrum arising from compactification using this construction by counting zero modes of the linearized equations of motion for the gaugino in the supergravity approximation. We rephrase the question in terms of a cohomology problem and show that for a trivial gauge bundle, this cohomology reduces to the Dolbeault cohomology of the 3-fold, which we then compute. Another check of string theory is to study the entropy of black holes made in string theory. In Chapter 3, We review the microstate counting of four dimensional black holes made from M theory. We then describe a new solution in five dimensions, the supersymmetric black ring, and describe its microscopic entropy using a similar counting. These agree with the semi-classical Bekenstein-Hawking entropy for these black holes. Finally, one powerful tool for quantum gravity is the holographic duality of string theory in an Anti de Sitter background and a theory living on its conformal boundary. Strominger conjectured a similar duality between quantum gravity in a de Sitter background and the corresponding theory on its boundary. In chapter 4 we examine issues with different representations of the conformal field theory on the boundary for a massive quantum field theory living in the bulk and try to write down a sensible CFT.

Topological defects in open string field theory

NASA Astrophysics Data System (ADS)

Kojita, Toshiko; Maccaferri, Carlo; Masuda, Toru; Schnabl, Martin

2018-04-01

We show how conformal field theory topological defects can relate solutions of open string field theory for different boundary conditions. To this end we generalize the results of Graham and Watts to include the action of defects on boundary condition changing fields. Special care is devoted to the general case when nontrivial multiplicities arise upon defect action. Surprisingly the fusion algebra of defects is realized on open string fields only up to a (star algebra) isomorphism.

The effective supergravity of little string theory

NASA Astrophysics Data System (ADS)

Antoniadis, Ignatios; Delgado, Antonio; Markou, Chrysoula; Pokorski, Stefan

2018-02-01

In this work we present the minimal supersymmetric extension of the five-dimensional dilaton-gravity theory that captures the main properties of the holographic dual of little string theory. It is described by a particular gauging of N=2 supergravity coupled with one vector multiplet associated with the string dilaton, along the U(1) subgroup of SU(2) R-symmetry. The linear dilaton in the fifth coordinate solution of the equations of motion (with flat string frame metric) breaks half of the supersymmetries to N=1 in four dimensions. Interest in the linear dilaton model has lately been revived in the context of the clockwork mechanism, which has recently been proposed as a new source of exponential scale separation in field theory.

Classical theory of radiating strings

NASA Technical Reports Server (NTRS)

Copeland, Edmund J.; Haws, D.; Hindmarsh, M.

1990-01-01

The divergent part of the self force of a radiating string coupled to gravity, an antisymmetric tensor and a dilaton in four dimensions are calculated to first order in classical perturbation theory. While this divergence can be absorbed into a renormalization of the string tension, demanding that both it and the divergence in the energy momentum tensor vanish forces the string to have the couplings of compactified N = 1 D = 10 supergravity. In effect, supersymmetry cures the classical infinities.

Tensionless Strings and Supersymmetric Sigma Models: Aspects of the Target Space Geometry

NASA Astrophysics Data System (ADS)

Bredthauer, Andreas

2007-01-01

In this thesis, two aspects of string theory are discussed, tensionless strings and supersymmetric sigma models. The equivalent to a massless particle in string theory is a tensionless string. Even almost 30 years after it was first mentioned, it is still quite poorly understood. We discuss how tensionless strings give rise to exact solutions to supergravity and solve closed tensionless string theory in the ten dimensional maximally supersymmetric plane wave background, a contraction of AdS(5)xS(5) where tensionless strings are of great interest due to their proposed relation to higher spin gauge theory via the AdS/CFT correspondence. For a sigma model, the amount of supersymmetry on its worldsheet restricts the geometry of the target space. For N=(2,2) supersymmetry, for example, the target space has to be bi-hermitian. Recently, with generalized complex geometry, a new mathematical framework was developed that is especially suited to discuss the target space geometry of sigma models in a Hamiltonian formulation. Bi-hermitian geometry is so-called generalized Kaehler geometry but the relation is involved. We discuss various amounts of supersymmetry in phase space and show that this relation can be established by considering the equivalence between the Hamilton and Lagrange formulation of the sigma model. In the study of generalized supersymmetric sigma models, we find objects that favor a geometrical interpretation beyond generalized complex geometry.

Surface operators from M -strings

NASA Astrophysics Data System (ADS)

Mori, Hironori; Sugimoto, Yuji

2017-01-01

It has been found that surface operators have a significant role in Alday-Gaiotto-Tachikawa (AGT) relation. This duality is an outstanding consequence of M -theory, but it is actually encoded into the brane web for which the topological string can work. From this viewpoint, the surface defect in AGT relation is geometrically engineered as a toric brane realization. Also, there is a class of the brane configuration in M -theory called M -strings which can be translated into the language of the topological string. In this work, we propose a new M -string configuration which can realize AGT relation in the presence of the surface defect by utilizing the geometric transition in the refined topological string.

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

Faizal, Mir, E-mail: f2mir@uwaterloo.ca; Majumder, Barun, E-mail: barunbasanta@iitgn.ac.in

In this paper, we will incorporate the generalized uncertainty principle into field theories with Lifshitz scaling. We will first construct both bosonic and fermionic theories with Lifshitz scaling based on generalized uncertainty principle. After that we will incorporate the generalized uncertainty principle into a non-abelian gauge theory with Lifshitz scaling. We will observe that even though the action for this theory is non-local, it is invariant under local gauge transformations. We will also perform the stochastic quantization of this Lifshitz fermionic theory based generalized uncertainty principle.

Composite Fermions: Motivation, Successes, and Application to Fractional Quantum Hall Effect in Graphene

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

Jain, Jainendra

2011-07-15

The fractional quantum Hall effect (FQHE) is one of the most amazing collective states discovered in modern times. A remarkably detailed and accurate understanding of its nonperturbative physics has been achieved in terms of a new class of exotic particles called composite fermions. I will begin with a brief review of the composite fermion theory and its outstanding successes. The rest of the talk will be concerned with fractional quantum Hall effect in graphene, observed recently. I will present results of theoretical studies that demonstrate that composite fermions are formed in graphene as well, but the spin and valley degeneraciesmore » and the linear dispersion of electrons produce interesting new physics relative to that in the usual two-dimensional GaAs systems. Composite fermion theory allows detailed predictions about FQHE in graphene in regimes when either or both of the spin and valley degeneracies are broken. I will discuss the relevance of our theory to recent experiments. This work on FQHE in graphene has been performed in collaboration with Csaba Toke.« less

Exploring the spectrum of regularized bosonic string theory

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

Ambjørn, J., E-mail: ambjorn@nbi.dk; Makeenko, Y., E-mail: makeenko@nbi.dk

2015-03-15

We implement a UV regularization of the bosonic string by truncating its mode expansion and keeping the regularized theory “as diffeomorphism invariant as possible.” We compute the regularized determinant of the 2d Laplacian for the closed string winding around a compact dimension, obtaining the effective action in this way. The minimization of the effective action reliably determines the energy of the string ground state for a long string and/or for a large number of space-time dimensions. We discuss the possibility of a scaling limit when the cutoff is taken to infinity.

Entanglement Entropy in Two-Dimensional String Theory.

PubMed

Hartnoll, Sean A; Mazenc, Edward A

2015-09-18

To understand an emergent spacetime is to understand the emergence of locality. Entanglement entropy is a powerful diagnostic of locality, because locality leads to a large amount of short distance entanglement. Two-dimensional string theory is among the very simplest instances of an emergent spatial dimension. We compute the entanglement entropy in the large-N matrix quantum mechanics dual to two-dimensional string theory in the semiclassical limit of weak string coupling. We isolate a logarithmically large, but finite, contribution that corresponds to the short distance entanglement of the tachyon field in the emergent spacetime. From the spacetime point of view, the entanglement is regulated by a nonperturbative "graininess" of space.

Brane inflation and cosmic string tension in superstring theory

NASA Astrophysics Data System (ADS)

Firouzjahi, Hassan; Tye, S.-H. Henry

2005-03-01

In a simple reanalysis of the KKLMMT scenario, we argue that the slow roll condition in the D3-overline {D}3 -brane inflationary scenario in superstring theory requires no more than a moderate tuning. The cosmic string tension is very sensitive to the conformal coupling: with less fine-tuning, the cosmic string tension (as well as the ratio of tensor to scalar perturbation mode) increases rapidly and can easily saturate the present observational bound. In a multi-throat brane inflationary scenario, this feature substantially improves the chance of detecting and measuring the properties of the cosmic strings as a window to the superstring theory and our pre-inflationary universe.

Hardware-efficient fermionic simulation with a cavity-QED system

NASA Astrophysics Data System (ADS)

Zhu, Guanyu; Subaşı, Yiǧit; Whitfield, James D.; Hafezi, Mohammad

2018-03-01

In digital quantum simulation of fermionic models with qubits, non-local maps for encoding are often encountered. Such maps require linear or logarithmic overhead in circuit depth which could render the simulation useless, for a given decoherence time. Here we show how one can use a cavity-QED system to perform digital quantum simulation of fermionic models. In particular, we show that highly nonlocal Jordan-Wigner or Bravyi-Kitaev transformations can be efficiently implemented through a hardware approach. The key idea is using ancilla cavity modes, which are dispersively coupled to a qubit string, to collectively manipulate and measure qubit states. Our scheme reduces the circuit depth in each Trotter step of the Jordan-Wigner encoding by a factor of N2, comparing to the scheme for a device with only local connectivity, where N is the number of orbitals for a generic two-body Hamiltonian. Additional analysis for the Fermi-Hubbard model on an N × N square lattice results in a similar reduction. We also discuss a detailed implementation of our scheme with superconducting qubits and cavities.

Lectures from the European RTN Winter School on Strings, Supergravity and Gauge Fields, CERN, 15 19 January 2007

NASA Astrophysics Data System (ADS)

Derendinger, J.-P.; Scrucca, C. A.; Uranga, A.

2007-11-01

This special issue is devoted to the proceedings of the conference 'Winter School on Strings, Supergravity and Gauge Theories', which took place at CERN, the European Centre for Nuclear Research, in Geneva, Switzerland, from the 15 to the 19 of January 2007. This event was organized in the framework of the European Mobility Research and Training Network entitled 'Constituents, Fundamental Forces and Symmetries of the Universe'. It is part of a yearly series of scientific schools, which represents what is by now a well established tradition. The previous conferences have been held at SISSA, in Trieste, Italy, in February 2005 and at CERN in January 2006. The next will again take place at CERN, in January 2008. The school was primarily meant for young doctoral students and postdoctoral researchers working in the area of string theory. It consisted of several general lectures of four hours each, the notes of which are published in the present proceedings, and seven working group discussion sessions, focused on specific topics of the network research program. It was attended by approximatively 250 participants. The topics of the lectures were chosen to provide an introduction to some of the areas of recent progress, and to the open problems, in string theory. String theory is a compelling candidate for a theory of all interactions. A basic challenge in this field is therefore to explore the connection of string theory models and the laws of physics in different realms, like high-energy particle physics, early cosmology, or physics of strongly coupled gauge theories. Concerning the exploration of string theory compactifications leading to realistic models of particle physics, one of the main obstacles in this direction is the proper understanding of supersymmetry breaking. The lecture notes by Nathan Seiberg review the realization of spontaneous breaking of supersymmetry in field theory, including recent developments via the use of meta-stable long-lived vacua. It is possible that such an understanding proves crucial in the realization of supersymmetry breaking in string theory. A second long-standing obstacle, which is being tackled with recent techniques, is moduli stabilization, namely the removal of unwanted massless scalar fields from string models. The present status of this problem, and its prospects of solution via the introduction of general sets of fluxes in the compactification space, were covered in the lectures by Brian Wecht. Application of these ideas to connect string theory to particle physics will require a good understanding of the experimental situation at the forthcoming collider LHC at CERN, and the detection tools for signals of new physics, as reviewed in the lectures by Joe Lykken (not covered in the present issue). Along a different line, the role of moduli fields in string theory is expected to provide a natural explanation of models of inflation, and thus of the origin of the cosmological evolution of our universe. The lecture notes by Cliff Burgess provide a review of big bang cosmology, inflation, and its possible explanation in terms of string theory constructions, including some of the most recent results in the field (these notes also appear in the proceedings of two other schools held in the same period). A surprising recent application of string theory is the description, via the ideas of holography and duality between string theories and gauge theories, of physical properties of quantum chromodynamics at high temperature. Indeed experimental data on the physical properties of the quark gluon plasma, produced in heavy ion collision at the RHIC experiment in Brookhaven (and soon at the LHC at CERN) can be recovered, at a semi-quantitative level, from computations in a string theory dual of the system. These applications are reviewed in the lectures by David Mateos. The conference was financially supported by the European Commission under contract MRTN-CT-2004-005104 and by CERN. It was jointly organized by the Physics Institute of the University of Neuchâtel and the Theory Unit of the Physics Division of CERN. It is a great pleasure for us to warmly thank the Theory Unit of CERN for its very kind hospitality and for the high quality of the assistance and the infrastructures that it has provided. We also acknowledge helpful administrative assistance from the Physics Institute of the University of Neuchâtel. A special acknowledgement also goes to Denis Frank, for his very valuable help in preparing the conference web pages. Group photo

String theory embeddings of nonrelativistic field theories and their holographic Hořava gravity duals.

PubMed

Janiszewski, Stefan; Karch, Andreas

2013-02-22

We argue that generic nonrelativistic quantum field theories with a holographic description are dual to Hořava gravity. We construct explicit examples of this duality embedded in string theory by starting with relativistic dual pairs and taking a nonrelativistic scaling limit.

Negative branes, supergroups and the signature of spacetime

NASA Astrophysics Data System (ADS)

Dijkgraaf, Robbert; Heidenreich, Ben; Jefferson, Patrick; Vafa, Cumrun

2018-02-01

We study the realization of supergroup gauge theories using negative branes in string theory. We show that negative branes are intimately connected with the possibility of timelike compactification and exotic spacetime signatures previously studied by Hull. Isolated negative branes dynamically generate a change in spacetime signature near their worldvolumes, and are related by string dualities to a smooth M-theory geometry with closed timelike curves. Using negative D3-branes, we show that SU(0| N) supergroup theories are holographically dual to an exotic variant of type IIB string theory on {dS}_{3,2}× {\\overline{S}}^5 , for which the emergent dimensions are timelike. Using branes, mirror symmetry and Nekrasov's instanton calculus, all of which agree, we derive the Seiberg-Witten curve for N=2 SU( N | M ) gauge theories. Together with our exploration of holography and string dualities for negative branes, this suggests that supergroup gauge theories may be non-perturbatively well-defined objects, though several puzzles remain.

Conductivity predictions for the 5/2 fractional quantum Hall state using the composite fermion superconductor model

NASA Astrophysics Data System (ADS)

Foster, Kerwin Crayton

The fractional quantum Hall effect (FQHE) occurs when a two-dimensional electron gas is placed in a strong magnetic field at low temperatures. When this effect occurs the Hall resistance, RH, defined to be the Hall voltage divided by the current, is quantized, with RH = (1/nu)h/ e2 where nu = p/q is the Landau level filling fraction; and p and q are relatively prime integers. For almost all observed FQHE states, q is odd with one notable exception: the nu = 5/2 FQHE state. Understanding the nature of this incompressible even-denominator state is one of the central questions in the theory of the FQHE and is the subject of this Dissertation. We use a powerful theoretical tool for studying the FQHE: composite fermion theory. Composite fermions can be viewed as electrons bound to an even number of magnetic flux quanta. Jain has shown that the FQHE for electrons can be viewed as an integer quantum Hall effect (p = 1) for composite fermions. More recently, Halperin, Lee and Read developed a successful theory of the compressible nu = 1/2 state using composite fermions. There is now compelling theoretical evidence that the 5/2 state is a so-called Moore-Read state---a state which can be viewed as a spin-polarized p-wave superconductor of composite fermions. We have developed a semi-phenomenological description of this state by modifying the Halperin-Lee-Read theory, adding a p-wave pairing interaction between composite fermions by hand. The electromagnetic response functions for the resulting superconducting state of composite fermions are then calculated. We show that these response functions exhibit the expected BCS 'coherence factor' effects, such as the Hebel-Slichter peak. Using the composite fermion response functions, we then calculate the corresponding electronic response functions using Chern-Simons theory. We find that in the electronic response, the most striking coherence factor effects (e.g., the Hebel-Slichter peak) are strongly suppressed. However, the low-temperature o = 2Delta threshold behavior does show clear coherence factor effects. Finally, we use our model to predict the wave-vector and frequency dependence of the longitudinal conductivity, sigmaxx( q, o), which can be measured in surface-acoustic-wave propagation experiments.

Electromagnetic interaction in the theory of straight strings

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

Nikitin, I.N.; Pron`ko, G.P.

1995-06-01

A scheme is proposed for including electromagnetic interaction into the theories of stretched relativistic objects. In the theory of the straight string, the operator of electromagnetic interaction is constructed, and form factors of electromagnetic transitions are calculated. 6 refs., 1 fig.

Is the Orthographic/Phonological Onset a Single Unit in Reading Aloud?

ERIC Educational Resources Information Center

Mousikou, Petroula; Coltheart, Max; Saunders, Steven; Yen, Lisa

2010-01-01

Two main theories of visual word recognition have been developed regarding the way orthographic units in printed words map onto phonological units in spoken words. One theory suggests that a string of single letters or letter clusters corresponds to a string of phonemes (Coltheart, 1978; Venezky, 1970), while the other suggests that a string of…

Width of the confining string in Yang-Mills theory.

PubMed

Gliozzi, F; Pepe, M; Wiese, U-J

2010-06-11

We investigate the transverse fluctuations of the confining string connecting two static quarks in (2+1)D SU(2) Yang-Mills theory using Monte Carlo calculations. The exponentially suppressed signal is extracted from the large noise by a very efficient multilevel algorithm. The resulting width of the string increases logarithmically with the distance between the static quark charges. Corrections at intermediate distances due to universal higher-order terms in the effective string action are calculated analytically. They accurately fit the numerical data.

Hot string soup: Thermodynamics of strings near the Hagedorn transition

NASA Astrophysics Data System (ADS)

Lowe, David A.; Thorlacius, Lárus

1995-01-01

Above the Hagedorn energy density closed fundamental strings form a long string phase. The dynamics of weakly interacting long strings is described by a simple Boltzmann equation which can be solved explicitly for equilibrium distributions. The averge total number of long strings grows logarithmically with total energy in the microcanonical ensemble. This is consistent with calculations of the free single string density of states provided the thermodynamic limit is carefully defined. If the theory contains open strings the long string phase is suppressed.

How could (should) we make contact between string/M-theory and our four-dimensional world, and associated LHC predictions?

NASA Astrophysics Data System (ADS)

Kane, Gordon

2015-12-01

String/M-theory is an exciting framework within which we try to understand our universe and its properties. Compactified string/M-theories address and offer solutions to almost every important question and issue in particle physics and particle cosmology. But earlier goals of finding a top-down “vacuum selection” principle and deriving the 4D theory have not yet been realized. Does that mean we should stop trying, as nearly all string theorists have? Or can we proceed in the historical way to make a few generic, robust assumptions not closely related to observables, and follow where they lead to testable predictions and explanations? Making only very generic assumptions is a significant issue. I discuss how to try to proceed with this approach, particularly in M-theory compactified on a 7D manifold of G2 holonomy. One goal is to understand our universe as a string/M-theory vacuum for its own sake, in the long tradition of trying to understand our world, and what that implies. In addition, understanding our vacuum may be a prelude to understanding its connection to the multiverse.

Probing the string winding sector

NASA Astrophysics Data System (ADS)

Aldazabal, Gerardo; Mayo, Martín; Nuñez, Carmen

2017-03-01

We probe a slice of the massive winding sector of bosonic string theory from toroidal compactifications of Double Field Theory (DFT). This string subsector corresponds to states containing one left and one right moving oscillators. We perform a generalized Kaluza Klein compactification of DFT on generic 2 n-dimensional toroidal constant backgrounds and show that, up to third order in fluctuations, the theory coincides with the corresponding effective theory of the bosonic string compactified on n-dimensional toroidal constant backgrounds, obtained from three-point amplitudes. The comparison between both theories is facilitated by noticing that generalized diffeomorphisms in DFT allow to fix generalized harmonic gauge conditions that help in identifying the physical degrees of freedom. These conditions manifest as conformal anomaly cancellation requirements on the string theory side. The explicit expression for the gauge invariant effective action containing the physical massless sector (gravity+antisymmetric+gauge+ scalar fields) coupled to towers of generalized Kaluza Klein massive states (corresponding to compact momentum and winding modes) is found. The action acquires a very compact form when written in terms of fields carrying O( n, n) indices, and is explicitly T-duality invariant. The global algebra associated to the generalized Kaluza Klein compactification is discussed.

S-Duality, Deconstruction and Confinement for a Marginal Deformation of N=4 SUSY Yang-Mills

NASA Astrophysics Data System (ADS)

Dorey, Nick

2004-08-01

We study an exactly marginal deformation of Script N = 4 SUSY Yang-Mills with gauge group U(N) using field theory and string theory methods. The classical theory has a Higgs branch for rational values of the deformation parameter. We argue that the quantum theory also has an S-dual confining branch which cannot be seen classically. The low-energy effective theory on these branches is a six-dimensional non-commutative gauge theory with sixteen supercharges. Confinement of magnetic and electric charges, on the Higgs and confining branches respectively, occurs due to the formation of BPS-saturated strings in the low energy theory. The results also suggest a new way of deconstructing Little String Theory as a large-N limit of a confining gauge theory in four dimensions.

Critical string from non-Abelian vortex in four dimensions

DOE PAGES

Shifman, M.; Yung, A.

2015-09-25

In a class of non-Abelian solitonic vortex strings supported in certain N = 2 super-Yang–Mills theories we search for the vortex which can behave as a critical fundamental string. We use the Polchinski–Strominger criterion of the ultraviolet completeness. We identify an appropriate four-dimensional bulk theory: it has the U(2) gauge group, the Fayet–Iliopoulos term and four flavor hypermultiplets. It supports semilocal vortices with the world-sheet theory for orientational (size) moduli described by the weighted CP(2,2) model. The latter is superconformal. Its target space is six-dimensional. The overall Virasoro central charge is critical. Lastly, we show that the world-sheet theory onmore » the vortex supported in this bulk model is the bona fide critical string.« less

Fermionic Field Theory for Trees and Forests

NASA Astrophysics Data System (ADS)

Caracciolo, Sergio; Jacobsen, Jesper Lykke; Saleur, Hubert; Sokal, Alan D.; Sportiello, Andrea

2004-08-01

We prove a generalization of Kirchhoff’s matrix-tree theorem in which a large class of combinatorial objects are represented by non-Gaussian Grassmann integrals. As a special case, we show that unrooted spanning forests, which arise as a q→0 limit of the Potts model, can be represented by a Grassmann theory involving a Gaussian term and a particular bilocal four-fermion term. We show that this latter model can be mapped, to all orders in perturbation theory, onto the N-vector model at N=-1 or, equivalently, onto the σ model taking values in the unit supersphere in R1|2. It follows that, in two dimensions, this fermionic model is perturbatively asymptotically free.

Large-D gravity and low-D strings.

PubMed

Emparan, Roberto; Grumiller, Daniel; Tanabe, Kentaro

2013-06-21

We show that in the limit of a large number of dimensions a wide class of nonextremal neutral black holes has a universal near-horizon limit. The limiting geometry is the two-dimensional black hole of string theory with a two-dimensional target space. Its conformal symmetry explains the properties of massless scalars found recently in the large-D limit. For black branes with string charges, the near-horizon geometry is that of the three-dimensional black strings of Horne and Horowitz. The analogies between the α' expansion in string theory and the large-D expansion in gravity suggest a possible effective string description of the large-D limit of black holes. We comment on applications to several subjects, in particular to the problem of critical collapse.

Chiral phase transition from string theory.

PubMed

Parnachev, Andrei; Sahakyan, David A

2006-09-15

The low energy dynamics of a certain D-brane configuration in string theory is described at weak t'Hooft coupling by a nonlocal version of the Nambu-Jona-Lasinio model. We study this system at finite temperature and strong t'Hooft coupling, using the string theory dual. We show that for sufficiently low temperatures chiral symmetry is broken, while for temperatures larger then the critical value, it gets restored. We compute the latent heat and observe that the phase transition is of the first order.

Yang-Mills gauge conditions from Witten's open string field theory

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

Feng Haidong; Siegel, Warren

2007-02-15

We construct the Zinn-Justin-Batalin-Vilkovisky action for tachyons and gauge bosons from Witten's 3-string vertex of the bosonic open string without gauge fixing. Through canonical transformations, we find the off-shell, local, gauge-covariant action up to 3-point terms, satisfying the usual field theory gauge transformations. Perturbatively, it can be extended to higher-point terms. It also gives a new gauge condition in field theory which corresponds to the Feynman-Siegel gauge on the world-sheet.

Anomaly of strings of 6d {N}=(1,0) theories

NASA Astrophysics Data System (ADS)

Shimizu, Hiroyuki; Tachikawa, Yuji

2016-11-01

We obtain the anomaly polynomial of strings of general 6d {N}=(1,0) theories in terms of anomaly inflow. Our computation sheds some light on the reason why the simplest 6d {N}=(1,0) theory has E 8 flavor symmetry, and also partially explains a curious numerology in F-theory.

Dual little strings from F-theory and flop transitions

NASA Astrophysics Data System (ADS)

Hohenegger, Stefan; Iqbal, Amer; Rey, Soo-Jong

2017-07-01

A particular two-parameter class of little string theories can be described by M parallel M5-branes probing a transverse affine A N - 1 singularity. We previously discussed the duality between the theories labelled by ( N, M) and ( M, N). In this work, we propose that these two are in fact only part of a larger web of dual theories. We provide evidence that the theories labelled by ( N, M) and (NM/k,k) are dual to each other, where k = gcd( N, M). To argue for this duality, we use a geometric realization of these little string theories in terms of F-theory compactifications on toric, non-compact Calabi-Yau threefolds X N, M which have a double elliptic fibration structure. We show explicitly for a number of examples that X NM/ k, k is part of the extended moduli space of X N, M , i.e. the two are related through symmetry transformations and flop transitions. By working out the full duality map, we provide a simple check at the level of the free energy of little string theories.

Magnetotransport in Layered Dirac Fermion System Coupled with Magnetic Moments

NASA Astrophysics Data System (ADS)

Iwasaki, Yoshiki; Morinari, Takao

2018-03-01

We theoretically investigate the magnetotransport of Dirac fermions coupled with localized moments to understand the physical properties of the Dirac material EuMnBi2. Using an interlayer hopping form, which simplifies the complicated interaction between the layers of Dirac fermions and the layers of magnetic moments in EuMnBi2, the theory reproduces most of the features observed in this system. The hysteresis observed in EuMnBi2 can be caused by the valley splitting that is induced by the spin-orbit coupling and the external magnetic field with the molecular field created by localized moments. Our theory suggests that the magnetotransport in EuMnBi2 is due to the interplay among Dirac fermions, localized moments, and spin-orbit coupling.

Cosmic strings

NASA Technical Reports Server (NTRS)

Bennett, David P.

1988-01-01

Cosmic strings are linear topological defects which are predicted by some grand unified theories to form during a spontaneous symmetry breaking phase transition in the early universe. They are the basis for the only theories of galaxy formation aside from quantum fluctuations from inflation based on fundamental physics. In contrast to inflation, they can also be observed directly through gravitational lensing and their characterisitc microwave background anisotropy. It was recently discovered that details of cosmic string evolution are very differnt from the so-called standard model that was assumed in most of the string-induced galaxy formation calculations. Therefore, the details of galaxy formation in the cosmic string models are currently very uncertain.

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

Aharony, Ofer; Benini, Francesco; Hsin, Po -Shen

In the last few years several dualities were found between the low-energy behaviors of Chern-Simons-matter theories with unitary gauge groups coupled to scalars, and similar theories coupled to fermions. In this paper we generalize those dualities to orthogonal and symplectic gauge groups. In particular, we conjecture dualities between SO(N) k Chern-Simons theories coupled to N f real scalars in the fundamental representation, and SO(k)- N+N f /2 coupled to N f real (Majorana) fermions in the fundamental. For N f = 0 these are just level-rank dualities of pure Chern-Simons theories, whose precise form we clarify. They lead us tomore » propose new gapped boundary states of topological insulators and superconductors. As a result, for k = 1 we get an interesting low-energy duality between N f free Majorana fermions and an SO( N) 1 Chern-Simons theory coupled to N f scalar fields (with N f ≤ N-2).« less

Fermion-induced quantum critical points.

PubMed

Li, Zi-Xiang; Jiang, Yi-Fan; Jian, Shao-Kai; Yao, Hong

2017-08-22

A unified theory of quantum critical points beyond the conventional Landau-Ginzburg-Wilson paradigm remains unknown. According to Landau cubic criterion, phase transitions should be first-order when cubic terms of order parameters are allowed by symmetry in the Landau-Ginzburg free energy. Here, from renormalization group analysis, we show that second-order quantum phase transitions can occur at such putatively first-order transitions in interacting two-dimensional Dirac semimetals. As such type of Landau-forbidden quantum critical points are induced by gapless fermions, we call them fermion-induced quantum critical points. We further introduce a microscopic model of SU(N) fermions on the honeycomb lattice featuring a transition between Dirac semimetals and Kekule valence bond solids. Remarkably, our large-scale sign-problem-free Majorana quantum Monte Carlo simulations show convincing evidences of a fermion-induced quantum critical points for N = 2, 3, 4, 5 and 6, consistent with the renormalization group analysis. We finally discuss possible experimental realizations of the fermion-induced quantum critical points in graphene and graphene-like materials.Quantum phase transitions are governed by Landau-Ginzburg theory and the exceptions are rare. Here, Li et al. propose a type of Landau-forbidden quantum critical points induced by gapless fermions in two-dimensional Dirac semimetals.

BPS States, Crystals, and Matrices

DOE PAGES

Sułkowski, Piotr

2011-01-01

We review free fermion, melting crystal, and matrix model representations of wall-crossing phenomena on local, toric Calabi-Yau manifolds. We consider both unrefined and refined BPS counting of closed BPS states involving D2- and D0-branes bound to a D6-brane, as well as open BPS states involving open D2-branes ending on an additional D4-brane. Appropriate limit of these constructions provides, among the others, matrix model representation of refined and unrefined topological string amplitudes.

Phases of QCD3 from non-SUSY Seiberg duality and brane dynamics

NASA Astrophysics Data System (ADS)

Armoni, Adi; Niarchos, Vasilis

2018-05-01

We consider a nonsupersymmetric USp Yang-Mills Chern-Simons gauge theory coupled to fundamental flavors. The theory is realised in type-IIB string theory via an embedding in a Hanany-Witten brane configuration which includes an orientifold and antibranes. We argue that the theory admits a magnetic Seiberg dual. Using the magnetic dual we identify dynamics in field theory and brane physics that correspond to various phases, obtaining a better understanding of three-dimensional bosonization and dynamical breaking of flavor symmetry in USp QCD3 theory. In field theory both phases correspond to magnetic "squark" condensation. In string theory, they correspond to open string tachyon condensation and brane reconnection. We also discuss other phases where the magnetic `squark' is massive. Finally, we briefly comment on the case of unitary gauge groups.

Non-associativity in non-geometric string and M-theory backgrounds, the algebra of octonions, and missing momentum modes

DOE PAGES

Günaydin, Murat; Lüst, Dieter; Malek, Emanuel

2016-11-07

We propose a non-associative phase space algebra for M-theory backgrounds with locally non-geometric fluxes based on the non-associative algebra of octonions. Our proposal is based on the observation that the non-associative algebra of the non-geometric R-flux background in string theory can be obtained by a proper contraction of the simple Malcev algebra generated by imaginary octonions. Furthermore, by studying a toy model of a four-dimensional locally non-geometric M-theory background which is dual to a twisted torus, we show that the non-geometric background is “missing” a momentum mode. The resulting seven-dimensional phase space can thus be naturally identified with the imaginarymore » octonions. This allows us to interpret the full uncontracted algebra of imaginary octonions as the uplift of the string theory R-flux algebra to M-theory, with the contraction parameter playing the role of the string coupling constant g s.« less

Non-associativity in non-geometric string and M-theory backgrounds, the algebra of octonions, and missing momentum modes

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

Günaydin, Murat; Lüst, Dieter; Malek, Emanuel

We propose a non-associative phase space algebra for M-theory backgrounds with locally non-geometric fluxes based on the non-associative algebra of octonions. Our proposal is based on the observation that the non-associative algebra of the non-geometric R-flux background in string theory can be obtained by a proper contraction of the simple Malcev algebra generated by imaginary octonions. Furthermore, by studying a toy model of a four-dimensional locally non-geometric M-theory background which is dual to a twisted torus, we show that the non-geometric background is “missing” a momentum mode. The resulting seven-dimensional phase space can thus be naturally identified with the imaginarymore » octonions. This allows us to interpret the full uncontracted algebra of imaginary octonions as the uplift of the string theory R-flux algebra to M-theory, with the contraction parameter playing the role of the string coupling constant g s.« less

Infrared fixed point of SU(2) gauge theory with six flavors

NASA Astrophysics Data System (ADS)

Leino, Viljami; Rummukainen, Kari; Suorsa, Joni; Tuominen, Kimmo; Tähtinen, Sara

2018-06-01

We compute the running of the coupling in SU(2) gauge theory with six fermions in the fundamental representation of the gauge group. We find strong evidence that this theory has an infrared stable fixed point at strong coupling and measure also the anomalous dimension of the fermion mass operator at the fixed point. This theory therefore likely lies close to the boundary of the conformal window and will display novel infrared dynamics if coupled with the electroweak sector of the Standard Model.

Cosmic strings and superconducting cosmic strings

NASA Technical Reports Server (NTRS)

Copeland, Edmund

1988-01-01

The possible consequences of forming cosmic strings and superconducting cosmic strings in the early universe are discussed. Lecture 1 describes the group theoretic reasons for and the field theoretic reasons why cosmic strings can form in spontaneously broken gauge theories. Lecture 2 discusses the accretion of matter onto string loops, emphasizing the scenario with a cold dark matter dominated universe. In lecture 3 superconducting cosmic strings are discussed, as is a mechanism which leads to the formation of structure from such strings.

Fermion number anomaly with the fluffy mirror fermion

NASA Astrophysics Data System (ADS)

Okumura, Ken-ichi; Suzuki, Hiroshi

2016-12-01

Quite recently, Grabowska and Kaplan presented a 4-dimensional lattice formulation of chiral gauge theories based on the chiral overlap operator. We study this formulation from the perspective of the fermion number anomaly and possible associated phenomenology. A simple argument shows that the consistency of the formulation implies that the fermion with the opposite chirality to the physical one, the "fluffy mirror fermion" or "fluff", suffers from the fermion number anomaly in the same magnitude (with the opposite sign) as the physical fermion. This immediately shows that if at least one of the fluff quarks is massless, the formulation provides a simple viable solution to the strong CP problem. Also, if the fluff interacts with gravity essentially in the same way as the physical fermion, the formulation can realize the asymmetric dark matter scenario.

A cosmic book. [of physics of early universe

NASA Technical Reports Server (NTRS)

Peebles, P. J. E.; Silk, Joseph

1988-01-01

A system of assigning odds to the basic elements of cosmological theories is proposed in order to evaluate the strengths and weaknesses of the theories. A figure of merit for the theories is obtained by counting and weighing the plausibility of each of the basic elements that is not substantially supported by observation or mature fundamental theory. The magnetized strong model is found to be the most probable. In order of decreasing probability, the ranking for the rest of the models is: (1) the magnetized string model with no exotic matter and the baryon adiabatic model; (2) the hot dark matter model and the model of cosmic string loops; (3) the canonical cold dark matter model, the cosmic string loops model with hot dark matter, and the baryonic isocurvature model; and (4) the cosmic string loops model with no exotic matter.

CERN Winter School on Supergravity, Strings, and Gauge Theory 2010

ScienceCinema

None

2018-05-15

The CERN Winter School on Supergravity, Strings, and Gauge Theory is the analytic continuation of the yearly training school of the former EC-RTN string network Constituents, Fundamental Forces and Symmetries of the Universe. The 2010 edition of the school is supported and organized by the CERN Theory Divison, and will take place from Monday January 25 to Friday January 29, at CERN. As its predecessors, this school is meant primarily for training of doctoral students and young postdoctoral researchers in recent developments in theoretical high-energy physics and string theory. The programme of the school will consist of five series of pedagogical lectures, complemented by tutorial discussion sessions in the afternoons. Previous schools in this series were organized in 2005 at SISSA in Trieste, and in 2006, 2007, 2008, and 2009 at CERN, Geneva.

Infrared problem in non-Abelian gauge theory

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

Yao, Y.

1976-03-22

I extend the Bloch--Nordsieck idea to show that in the lowest nontrivial order of radiative correction the fermion--fermion and gauge-meson--fermion scattering rates are finite, provided that they are averaged over the initial and summed over the final internal spin states. Questions of the physical gauge coupling and infrared slavery are discussed. (AIP)

Domain wall fermion and CP symmetry breaking

NASA Astrophysics Data System (ADS)

Fujikawa, Kazuo; Suzuki, Hiroshi

2003-02-01

We examine the CP properties of chiral gauge theory defined by a formulation of the domain wall fermion, where the light field variables q and q¯ together with Pauli-Villars fields Q and Q¯ are utilized. It is shown that this domain wall representation in the infinite flavor limit N=∞ is valid only in the topologically trivial sector, and that the conflict among lattice chiral symmetry, strict locality and CP symmetry still persists for finite lattice spacing a. The CP transformation generally sends one representation of lattice chiral gauge theory into another representation of lattice chiral gauge theory, resulting in the inevitable change of propagators. A modified form of lattice CP transformation motivated by the domain wall fermion, which keeps the chiral action in terms of the Ginsparg-Wilson fermion invariant, is analyzed in detail; this provides an alternative way to understand the breaking of CP symmetry at least in the topologically trivial sector. We note that the conflict with CP symmetry could be regarded as a topological obstruction. We also discuss the issues related to the definition of Majorana fermions in connection with the supersymmetric Wess-Zumino model on the lattice.

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

McGreevy, John Austen; /Stanford U., Phys. Dept.

This thesis is a study of D-branes in string compactifications. In this context, D-branes are relevant as an important component of the nonperturbative spectrum, as an incisive probe of these backgrounds, and as a natural stringy tool for localizing gauge interactions. In the first part of the thesis, we discuss half-BPS D-branes in compactifications of type II string theory on Calabi-Yau threefolds. The results we describe for these objects are pertinent both in their role as stringy brane-worlds, and in their role as solitonic objects. In particular, we determine couplings of these branes to the moduli determining the closed-string geometry,more » both perturbatively and non-perturbatively in the worldsheet expansion. We provide a local model for transitions in moduli space where the BPS spectrum jumps, and discuss the extension of mirror symmetry between Calabi-Yau manifolds to the case when D-branes are present. The next section is an interlude which provides some applications of D-branes to other curved backgrounds of string theory. In particular, we discuss a surprising phenomenon in which fundamental strings moving through background Ramond-Ramond fields dissolve into large spherical D3-branes. This mechanism is used to explain a previously-mysterious fact discovered via the AdS-CFT correspondence. Next, we make a connection between type IIA string vacua of the type discussed in the first section and M-theory compactifications on manifolds of G{sub 2} holonomy. Finally we discuss constructions of string vacua which do not have large radius limits. In the final part of the thesis, we develop techniques for studying the worldsheets of open strings ending on the curved D-branes studied in the first section. More precisely, we formulate a large class of massive two-dimensional gauge theories coupled to boundary matter, which flow in the infrared to the relevant boundary conformal field theories. Along with many other applications, these techniques are used to describe world-volume theories of point-like D-probes of various Calabi-Yau threefolds.« less

New dimensions for wound strings: The modular transformation of geometry to topology

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

McGreevy, John; Silverstein, Eva; Starr, David

2007-02-15

We show, using a theorem of Milnor and Margulis, that string theory on compact negatively curved spaces grows new effective dimensions as the space shrinks, generalizing and contextualizing the results in E. Silverstein, Phys. Rev. D 73, 086004 (2006).. Milnor's theorem relates negative sectional curvature on a compact Riemannian manifold to exponential growth of its fundamental group, which translates in string theory to a higher effective central charge arising from winding strings. This exponential density of winding modes is related by modular invariance to the infrared small perturbation spectrum. Using self-consistent approximations valid at large radius, we analyze this correspondencemore » explicitly in a broad set of time-dependent solutions, finding precise agreement between the effective central charge and the corresponding infrared small perturbation spectrum. This indicates a basic relation between geometry, topology, and dimensionality in string theory.« less

String-theoretic deformation of the Parke-Taylor factor

NASA Astrophysics Data System (ADS)

Mizera, Sebastian; Zhang, Guojun

2017-09-01

Scattering amplitudes in a range of quantum field theories can be computed using the Cachazo-He-Yuan (CHY) formalism. In theories with color ordering, the key ingredient is the so-called Parke-Taylor factor. In this paper we give a fully SL (2 ,C )-covariant definition and study the properties of a new integrand called the "string Parke-Taylor" factor. It has an α' expansion whose leading coefficient is the field-theoretic Parke-Taylor factor. Its main application is that it leads to a CHY formulation of open string tree-level amplitudes. In fact, the definition of the string Parke-Taylor factor was motivated by trying to extend the compact formula for the first α' correction found by He and Zhang, while the main ingredient in its definition is a determinant of a matrix introduced in the context of string theory by Stieberger and Taylor.

String universality in ten dimensions.

PubMed

Adams, Allan; Taylor, Washington; Dewolfe, Oliver

2010-08-13

We show that the N=1 supergravity theories in ten dimensions with gauge groups U(1){496} and E{8}×U(1){248} are not consistent quantum theories. Cancellation of anomalies cannot be made compatible with supersymmetry and Abelian gauge invariance. Thus, in ten dimensions all supersymmetric theories of gravity without known inconsistencies are realized in string theory.

Worldsheet instantons and the amplitude for string pair production in an external field as a WKB exact functional integral

NASA Astrophysics Data System (ADS)

Gordon, James; Semenoff, Gordon W.

2018-05-01

We revisit the problem of charged string pair creation in a constant external electric field. The string states are massive and creation of pairs from the vacuum is a tunnelling process, analogous to the Schwinger process where charged particle-anti-particle pairs are created by an electric field. We find the instantons in the worldsheet sigma model which are responsible for the tunnelling events. We evaluate the sigma model partition function in the multi-instanton sector in the WKB approximation which keeps the classical action and integrates the quadratic fluctuations about the solution. We find that the summation of the result over all multi-instanton sectors reproduces the known amplitude. This suggests that corrections to the WKB limit must cancel. To show that they indeed cancel, we identify a fermionic symmetry of the sigma model which occurs in the instanton sectors and which is associated with collective coordinates. We demonstrate that the action is symmetric and that the interaction action is an exact form. These conditions are sufficient for localization of the worldsheet functional integral onto its WKB limit.

The large N limit of superconformal field theories and supergravity

NASA Astrophysics Data System (ADS)

Maldacena, Juan

1999-07-01

We show that the large N limit of certain conformal field theories in various dimensions include in their Hilbert space a sector describing supergravity on the product of Anti-deSitter spacetimes, spheres and other compact manifolds. This is shown by taking some branes in the full M/string theory and then taking a low energy limit where the field theory on the brane decouples from the bulk. We observe that, in this limit, we can still trust the near horizon geometry for large N. The enhanced supersymmetries of the near horizon geometry correspond to the extra supersymmetry generators present in the superconformal group (as opposed to just the super-Poincare group). The 't Hooft limit of 3+1N=4 super-Yang-Mills at the conformal point is shown to contain strings: they are IIB strings. We conjecture that compactifications of M/string theory on various Anti-deSitter spacetimes is dual to various conformal field theories. This leads to a new proposal for a definition of M-theory which could be extended to include five non-compact dimensions.

Chern-Simons gauge theory on orbifolds: Open strings from three dimensions

NASA Astrophysics Data System (ADS)

Hořava, Petr

1996-12-01

Chern-Simons gauge theory is formulated on three-dimensional Z2 orbifolds. The locus of singular points on a given orbifold is equivalent to a link of Wilson lines. This allows one to reduce any correlation function on orbifolds to a sum of more complicated correlation functions in the simpler theory on manifolds. Chern-Simons theory on manifolds is known to be related to two-dimensional (2D) conformal field theory (CFT) on closed-string surfaces; here it is shown that the theory on orbifolds is related to 2D CFT of unoriented closed- and open-string models, i.e. to worldsheet orbifold models. In particular, the boundary components of the worldsheet correspond to the components of the singular locus in the 3D orbifold. This correspondence leads to a simple identification of the open-string spectra, including their Chan-Paton degeneration, in terms of fusing Wilson lines in the corresponding Chern-Simons theory. The correspondence is studied in detail, and some exactly solvable examples are presented. Some of these examples indicate that it is natural to think of the orbifold group Z2 as a part of the gauge group of the Chern-Simons theory, thus generalizing the standard definition of gauge theories.

Background Independence and Duality Invariance in String Theory.

PubMed

Hohm, Olaf

2017-03-31

Closed string theory exhibits an O(D,D) duality symmetry on tori, which in double field theory is manifest before compactification. I prove that to first order in α^{'} there is no manifestly background independent and duality invariant formulation of bosonic string theory in terms of a metric, b field, and dilaton. To this end I use O(D,D) invariant second order perturbation theory around flat space to show that the unique background independent candidate expression for the gauge algebra at order α^{'} is inconsistent with the Jacobi identity. A background independent formulation exists instead for frame variables subject to α^{'}-deformed frame transformations (generalized Green-Schwarz transformations). Potential applications for curved backgrounds, as in cosmology, are discussed.

Carving out the end of the world or (superconformal bootstrap in six dimensions)

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

Chang, Chi-Ming; Lin, Ying-Hsuan

We bootstrap N=(1,0) superconformal field theories in six dimensions, by analyzing the four-point function of flavor current multiplets. By assuming E 8 flavor group, we present universal bounds on the central charge C T and the flavor central charge C J. Based on the numerical data, we conjecture that the rank-one E-string theory saturates the universal lower bound on C J , and numerically determine the spectrum of long multiplets in the rank-one E-string theory. We comment on the possibility of solving the higher-rank E-string theories by bootstrap and thereby probing M-theory on AdS 7×S 4/Z 2 .

Carving out the end of the world or (superconformal bootstrap in six dimensions)

DOE PAGES

Chang, Chi-Ming; Lin, Ying-Hsuan

2017-08-29

We bootstrap N=(1,0) superconformal field theories in six dimensions, by analyzing the four-point function of flavor current multiplets. By assuming E 8 flavor group, we present universal bounds on the central charge C T and the flavor central charge C J. Based on the numerical data, we conjecture that the rank-one E-string theory saturates the universal lower bound on C J , and numerically determine the spectrum of long multiplets in the rank-one E-string theory. We comment on the possibility of solving the higher-rank E-string theories by bootstrap and thereby probing M-theory on AdS 7×S 4/Z 2 .

New 5-adic Cantor sets and fractal string.

PubMed

Kumar, Ashish; Rani, Mamta; Chugh, Renu

2013-01-01

In the year (1879-1884), George Cantor coined few problems and consequences in the field of set theory. One of them was the Cantor ternary set as a classical example of fractals. In this paper, 5-adic Cantor one-fifth set as an example of fractal string have been introduced. Moreover, the applications of 5-adic Cantor one-fifth set in string theory have also been studied.

Breakdown of String Perturbation Theory for Many External Particles.

PubMed

Ghosh, Sudip; Raju, Suvrat

2017-03-31

We consider massless string scattering amplitudes in a limit where the number of external particles becomes very large, while the energy of each particle remains small. Using the growth of the volume of the relevant moduli space, and by means of independent numerical evidence, we argue that string perturbation theory breaks down in this limit. We discuss some remarkable implications for the information paradox.

String tensions in deformed Yang-Mills theory

NASA Astrophysics Data System (ADS)

Poppitz, Erich; Shalchian T., M. Erfan

2018-01-01

We study k-strings in deformed Yang-Mills (dYM) with SU(N) gauge group in the semiclassically calculable regime on R^3× S^1 . Their tensions Tk are computed in two ways: numerically, for 2 ≤ N ≤ 10, and via an analytic approach using a re-summed perturbative expansion. The latter serves both as a consistency check on the numerical results and as a tool to analytically study the large-N limit. We find that dYM k-string ratios Tk/T1 do not obey the well-known sine- or Casimir-scaling laws. Instead, we show that the ratios Tk/T1 are bound above by a square root of Casimir scaling, previously found to hold for stringlike solutions of the MIT Bag Model. The reason behind this similarity is that dYM dynamically realizes, in a theoretically controlled setting, the main model assumptions of the Bag Model. We also compare confining strings in dYM and in other four-dimensional theories with abelian confinement, notably Seiberg-Witten theory, and show that the unbroken Z_N center symmetry in dYM leads to different properties of k-strings in the two theories; for example, a "baryon vertex" exists in dYM but not in softly-broken Seiberg-Witten theory. Our results also indicate that, at large values of N, k-strings in dYM do not become free.

Application of a number-conserving boson expansion theory to Ginocchio's SO(8) model

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

Li, C.h.; Pedrocchi, V.G.; Tamura, T.

1986-05-01

A boson expansion theory based on a number-conserving quasiparticle approach is applied to Ginocchio's SO(8) fermion model. Energy spectra and E2 transition rates calculated by using this new boson mapping are presented and compared against the exact fermion values. A comparison with other boson approaches is also given.

Higgs-like mechanism for spontaneous spacetime symmetry breaking

NASA Astrophysics Data System (ADS)

Nishimura, Kimihide

2015-10-01

The study of spontaneous breakdown of spacetime symmetries leads to the discovery of another type of Higgs mechanism operating in a chiral SU(2) model. Some of the Nambu-Goldstone vector mesons emergent from simultaneous violations of gauge and Lorentz symmetries are, in this case, absorbed by a left-handed doublet and endow one of the fermions with a right-handed state, while another part becomes emergent as photons. Accordingly, this mechanism allows a chiral fermion to acquire a mass, and it may enable the emergent theory to reproduce the electromagnetism equivalent to the QED sector in the standard theory. It is also mentioned that the "fermion-boson puzzle" known in the presence of a 't Hooft-Polyakov monopole does not exist in our theory.

Mellin transforming the minimal model CFTs: AdS/CFT at strong curvature

DOE PAGES

Lowe, David A.

2016-07-14

Mack has conjectured that all conformal field theories are equivalent to string theories. Here, we explore the example of the two-dimensional minimal model CFTs and confirm that the Mellin transformed amplitudes have the desired properties of string theory in three-dimensional anti-de Sitter spacetime.

Finite-g Strings

NASA Astrophysics Data System (ADS)

Vicedo, Benoit

2008-10-01

In view of one day proving the AdS/CFT correspondence, a deeper understanding of string theory on certain curved backgrounds such as AdS_5xS^5 is required. In this dissertation we make a step in this direction by focusing on RxS^3. It was discovered in recent years that string theory on AdS_5xS^5 admits a Lax formulation. However, the complete statement of integrability requires not only the existence of a Lax formulation, but also that the resulting integrals of motion are in pairwise involution. This idea is central to the first part of this thesis. Exploiting this integrability we apply algebro-geometric methods to string theory on RxS^3 and obtain the general finite-gap solution. The construction is based on an invariant algebraic curve previously found in the AdS_5xS^5 case. However, encoding the dynamics of the solution requires specification of additional marked points. By restricting the symplectic structure of the string to this algebro-geometric data we derive the action-angle variables of the system. We then perform a first-principle semiclassical quantisation of string theory on RxS^3 as a toy model for strings on AdS_5xS^5. The result is exactly what one expects from the dual gauge theory perspective, namely the underlying algebraic curve discretises in a natural way. We also derive a general formula for the fluctuation energies around the generic finite-gap solution. The ideas used can be generalised to AdS_5xS^5.

String-driven inflation

NASA Technical Reports Server (NTRS)

Turok, Neil

1988-01-01

It is argued that, in fundamental string theories, as one traces the universe back in time a point is reached when the expansion rate is so fast that the rate of string creation due to quantum effects balances the dilution of the string density due to the expansion. One is therefore led into a phase of constant string density and an exponentially expanding universe. Fundamental strings therefore seem to lead naturally to inflation.

High energy physics, past, present and future

NASA Astrophysics Data System (ADS)

Sugawara, Hirotaka

2017-03-01

At the beginning of last century we witnessed the emergence of new physics, quantum theory and gravitational theory, which gave us correct understanding of the world of atoms and deep insight into the structure of universe we live in. Towards the end of the century, string theory emerged as the most promising candidate to unify these two theories. In this talk, I would like to assert that the understanding of the origin of physical constants, ℏ (Planck constant) for quantum theory, and G (Newton’s gravitational constant) for gravitational theory within the framework of string theory is the key to understanding string theory. Then, I will shift to experimental high energy physics and discuss the necessity of world-wide collaboration in the area of superconducting technology which is essential in constructing the 100 TeV hadron collider.

Baryon spectrum of SU(4) composite Higgs theory with two distinct fermion representations

NASA Astrophysics Data System (ADS)

Ayyar, Venkitesh; DeGrand, Thomas; Hackett, Daniel C.; Jay, William I.; Neil, Ethan T.; Shamir, Yigal; Svetitsky, Benjamin

2018-06-01

We use lattice simulations to compute the baryon spectrum of SU(4) lattice gauge theory coupled to dynamical fermions in the fundamental and two-index antisymmetric (sextet) representations simultaneously. This model is closely related to a composite Higgs model in which the chimera baryon made up of fermions from both representations plays the role of a composite top-quark partner. The dependence of the baryon masses on each underlying fermion mass is found to be generally consistent with a quark-model description and large-Nc scaling. We combine our numerical results with experimental bounds on the scale of the new strong sector to estimate a lower bound on the mass of the top-quark partner. We discuss some theoretical uncertainties associated with this estimate.

Adding gauge fields to Kaplan's fermions

NASA Astrophysics Data System (ADS)

Blum, T.; Kärkkäinen, Leo

1994-04-01

We experiment with adding dynamical gauge field to Kaplan (defect) fermions. In the case of U (1) gauge theory we use an inhomogenous Higgs mechanism to restrict the 3d gauge dynamics to a planar 2d defect. In our simulations the 3d theory produce the correct 2d gauge dynamics. We measure fermion propagators with dynamical gauge fields. They posses the correct chiral structure. The fermions at the boundary of the support of the gauge field (waveguide) are non-chiral, and have a mass two times heavier than the chiral modes. Moreover, these modes cannot be excited by a source at the defect; implying that they are dynamically decoupled. We have also checked that the anomaly relation is fullfilled for the case of a smooth external gauge field.

A class of exact classical solutions to string theory.

PubMed

Coley, A A

2002-12-31

We show that the recently obtained class of spacetimes for which all of the scalar curvature invariants vanish (which can be regarded as generalizations of pp-wave spacetimes) are exact solutions in string theory to all perturbative orders in the string tension scale. As a result the spectrum of the theory can be explicitly obtained, and these spacetimes are expected to provide some hints for the study of superstrings on more general backgrounds. Since these Lorentzian spacetimes suffer no quantum corrections to all loop orders they may also offer insights into quantum gravity.

Non-polynomial closed string field theory: loops and conformal maps

NASA Astrophysics Data System (ADS)

Hua, Long; Kaku, Michio

1990-11-01

Recently, we proposed the complete classical action for the non-polynomial closed string field theory, which succesfully reproduced all closed string tree amplitudes. (The action was simultaneously proposed by the Kyoto group). In this paper, we analyze the structure of the theory. We (a) compute the explicit conformal map for all g-loop, p-puncture diagrams, (b) compute all one-loop, two-puncture maps in terms of hyper-elliptic functions, and (c) analyze their modular structure. We analyze, but do not resolve, the question of modular invariance.

Probing the String Landscape

ScienceCinema

Dienes, Keith

2018-01-10

We are currently in the throes of a potentially huge paradigm shift in physics. Motivated by recent developments in string theory and the discovery of the so-called "string landscape", physicists are beginning to question the uniqueness of fundamental theories of physics and the methods by which such theories might be understood and investigated. In this colloquium, I will give a non-technical introduction to the nature of this paradigm shift and how it developed. I will also discuss some of the questions to which it has led, and the nature of the controversies it has spawned.

Segmented strings coupled to a B-field

NASA Astrophysics Data System (ADS)

Vegh, David

2018-04-01

In this paper we study segmented strings in AdS3 coupled to a background two-form whose field strength is proportional to the volume form. By changing the coupling, the theory interpolates between the Nambu-Goto string and the SL(2, ℝ) Wess-Zumino-Witten model. In terms of the kink momentum vectors, the action is independent of the coupling and the classical theory reduces to a single discrete-time Toda-type theory. The WZW model is a singular point in coupling space where the map into Toda variables degenerates.

Non-Abelian semilocal strings in N=2 supersymmetric QCD

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

Shifman, M.; Yung, A.; Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188300

2006-06-15

We consider a benchmark bulk theory in four dimensions: N=2 supersymmetric QCD with the gauge group U(N) and N{sub f} flavors of fundamental matter hypermultiplets (quarks). The nature of the Bogomol'nyi-Prasad-Sommerfield (BPS) strings in this benchmark theory crucially depends on N{sub f}. If N{sub f}{>=}N and all quark masses are equal, it supports non-Abelian BPS strings which have internal (orientational) moduli. If N{sub f}>N these strings become semilocal, developing additional moduli {rho} related to (unlimited) variations of their transverse size. Using the U(2) gauge group with N{sub f}=3, 4 as an example, we derive an effective low-energy theory on themore » (two-dimensional) string world sheet. Our derivation is field theoretic, direct and explicit: we first analyze the Bogomol'nyi equations for string-geometry solitons, suggest an ansatz, and solve it at large {rho}. Then we use this solution to obtain the world-sheet theory. In the semiclassical limit our result confirms the Hanany-Tong conjecture, which rests on brane-based arguments, that the world-sheet theory is an N=2 supersymmetric U(1) gauge theory with N positively and N{sub e}=N{sub f}-N negatively charged matter multiplets and the Fayet-Iliopoulos term determined by the four-dimensional coupling constant. We conclude that the Higgs branch of this model is not lifted by quantum effects. As a result, such strings cannot confine. Our analysis of infrared effects, not seen in the Hanany-Tong consideration, shows that, in fact, the derivative expansion can make sense only provided that the theory under consideration is regularized in the infrared, e.g. by the quark mass differences. The world-sheet action discussed in this paper becomes a bona fide low-energy effective action only if {delta}m{sub AB}{ne}0.« less

On the BV formalism of open superstring field theory in the large Hilbert space

NASA Astrophysics Data System (ADS)

Matsunaga, Hiroaki; Nomura, Mitsuru

2018-05-01

We construct several BV master actions for open superstring field theory in the large Hilbert space. First, we show that a naive use of the conventional BV approach breaks down at the third order of the antifield number expansion, although it enables us to define a simple "string antibracket" taking the Darboux form as spacetime antibrackets. This fact implies that in the large Hilbert space, "string fields-antifields" should be reassembled to obtain master actions in a simple manner. We determine the assembly of the string anti-fields on the basis of Berkovits' constrained BV approach, and give solutions to the master equation defined by Dirac antibrackets on the constrained string field-antifield space. It is expected that partial gauge-fixing enables us to relate superstring field theories based on the large and small Hilbert spaces directly: reassembling string fields-antifields is rather natural from this point of view. Finally, inspired by these results, we revisit the conventional BV approach and construct a BV master action based on the minimal set of string fields-antifields.

Instability of black strings in the third-order Lovelock theory

NASA Astrophysics Data System (ADS)

Giacomini, Alex; Henríquez-Báez, Carla; Lagos, Marcela; Oliva, Julio; Vera, Aldo

2016-05-01

We show that homogeneous black strings of third-order Lovelock theory are unstable under s-wave perturbations. This analysis is done in dimension D =9 , which is the lowest dimension that allows the existence of homogeneous black strings in a theory that contains only the third-order Lovelock term in the Lagrangian. As is the case in general relativity, the instability is produced by long wavelength perturbations and it stands for the perturbative counterpart of a thermal instability. We also provide a comparative analysis of the instabilities of black strings at a fixed radius in general relativity, Gauss-Bonnet, and third-order Lovelock theories. We show that the minimum critical wavelength that triggers the instability grows with the power of the curvature defined in the Lagrangian. The maximum exponential growth during the time of the perturbation is the largest in general relativity and it decreases with the number of curvatures involved in the Lagrangian.

Behavior of boundary string field theory associated with integrable massless flow.

PubMed

Fujii, A; Itoyama, H

2001-06-04

We put forward an idea that the boundary entropy associated with integrable massless flow of thermodynamic Bethe ansatz (TBA) is identified with tachyon action of boundary string field theory. We show that the temperature parametrizing a massless flow in the TBA formalism can be identified with tachyon energy for the classical action at least near the ultraviolet fixed point, i.e., the open string vacuum.

Evolution equation in the field theory of strings

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

Marui, M.; Sugamoto, A.; Oda, I.

This paper reports on a stringy version of the Altarelli-Parisi equation given within the field theory of bosonic strings formulated in the light-cone gauge. Using this equation, the authors study the behavior of the decay function of strings under the change of reference scale, especially imposing an assumption of large transverse momentum. In some cases the n-th moment of the decay function behaves very differently from QCD.

Stochastic quantization and holographic Wilsonian renormalization group of free massive fermion

NASA Astrophysics Data System (ADS)

Moon, Sung Pil

2018-06-01

We examine a suggested relation between stochastic quantization and the holographic Wilsonian renormalization group in the massive fermion case on Euclidean AdS space. The original suggestion about the general relation between the two theories is posted in arXiv:1209.2242. In the previous researches, it is already verified that scalar fields, U(1) gauge fields, and massless fermions are consistent with the relation. In this paper, we examine the relation in the massive fermion case. Contrary to the other case, in the massive fermion case, the action needs particular boundary terms to satisfy boundary conditions. We finally confirm that the proposed suggestion is also valid in the massive fermion case.

Spectroscopy of SU(4) composite Higgs theory with two distinct fermion representations

NASA Astrophysics Data System (ADS)

Ayyar, Venkitesh; DeGrand, Thomas; Golterman, Maarten; Hackett, Daniel C.; Jay, William I.; Neil, Ethan T.; Shamir, Yigal; Svetitsky, Benjamin

2018-04-01

We have simulated the SU(4) lattice gauge theory coupled to dynamical fermions in the fundamental and two-index antisymmetric (sextet) representations simultaneously. Such theories arise naturally in the context of composite Higgs models that include a partially composite top quark. We describe the low-lying meson spectrum of the theory and fit the pseudoscalar masses and decay constants to chiral perturbation theory. We infer as well the mass and decay constant of the Goldstone boson corresponding to the nonanomalous U(1) symmetry of the model. Our results are broadly consistent with large-Nc scaling and vector-meson dominance.

Hartree-Fock treatment of Fermi polarons using the Lee-Low-Pine transformation

NASA Astrophysics Data System (ADS)

Kain, Ben; Ling, Hong Y.

2017-09-01

We consider the Fermi polaron problem at zero temperature, where a single impurity interacts with noninteracting host fermions. We approach the problem starting with a Fröhlich-like Hamiltonian where the impurity is described with canonical position and momentum operators. We apply the Lee-Low-Pine (LLP) transformation to change the fermionic Fröhlich Hamiltonian into the fermionic LLP Hamiltonian, which describes a many-body system containing host fermions only. We adapt the self-consistent Hartree-Fock (HF) approach, first proposed by Edwards, to the fermionic LLP Hamiltonian in which a pair of host fermions with momenta k and k' interact with a potential proportional to k .k' . We apply the HF theory, which has the advantage of not restricting the number of particle-hole pairs, to repulsive Fermi polarons in one dimension. When the impurity and host fermion masses are equal our variational ansatz, where HF orbitals are expanded in terms of free-particle states, produces results in excellent agreement with McGuire's exact analytical results based on the Bethe ansatz. This work raises the prospect of using the HF ansatz and its time-dependent generalization as building blocks for developing all-coupling theories for both equilibrium and nonequilibrium Fermi polarons in higher dimensions.

Pointless strings

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

Periwal, V.

1988-01-01

The author proves that bosonic string perturbation theory diverges and is not Borel summable. This is an indication of a non-perturbative instability of the bosonic string vacuum. He formulates two-dimensional sigma models in terms of algebras of functions. He extends this formulation to general C* algebras. He illustrates the utility of these algebraic notions by calculating some determinants of interest in the study of string propagation in orbifold backgrounds. He studies the geometry of spaces of field theories and show that the vanishing of the curvature of the natural Gel'fand-Naimark-Segal metric on such spaces is exactly the strong associativity conditionmore » of the operator product expansion.He shows that string scattering amplitudes arise as invariants of renormalization, when he formulates renormalization in terms of rescalings of the metric on the string world-sheet.« less

Towards weakly constrained double field theory

NASA Astrophysics Data System (ADS)

Lee, Kanghoon

2016-08-01

We show that it is possible to construct a well-defined effective field theory incorporating string winding modes without using strong constraint in double field theory. We show that X-ray (Radon) transform on a torus is well-suited for describing weakly constrained double fields, and any weakly constrained fields are represented as a sum of strongly constrained fields. Using inverse X-ray transform we define a novel binary operation which is compatible with the level matching constraint. Based on this formalism, we construct a consistent gauge transform and gauge invariant action without using strong constraint. We then discuss the relation of our result to the closed string field theory. Our construction suggests that there exists an effective field theory description for massless sector of closed string field theory on a torus in an associative truncation.

Interpolating the Coulomb phase of little string theory

DOE PAGES

Lin, Ying -Hsuan; Shao, Shu -Heng; Wang, Yifan; ...

2015-12-03

We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity onmore » the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. As a result, we also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.« less

Final Report: "Strings 2014"

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

Witten, Edward

2015-10-21

The Strings 2014 meeting was held at Princeton University June 23-27, 2014, co-sponsored by Princeton University and the Institute for Advanced Study. The goal of the meeting was to provide a stimulating and up-to-date overview of research in string theory and its relations to other areas of physics and mathematics, ranging from geometry to quantum field theory, condensed matter physics, and more. This brief report lists committee members and speakers but contains no scientific information. Note that the talks at Strings 2014 were videotaped and are available on the conference website: http://physics.princeton.edustrings2014/Talk_titles.shtml.

What every physicist should know about string theory

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

Witten, Edward

2015-11-15

Some of nature’s rhymes—the appearance of similar structures in different areas of physics—underlie the way that string theory potentially unifies gravity with the other forces of nature and eliminates the ultraviolet divergences that plague quantum gravity.

Moduli space potentials for heterotic non-Abelian flux tubes: Weak deformation

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

Shifman, M.; Yung, A.; Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188300

2010-09-15

We consider N=2 supersymmetric QCD with the U(N) gauge group (with no Fayet-Iliopoulos term) and N{sub f} flavors of massive quarks deformed by the mass term {mu} for the adjoint matter, W={mu}A{sup 2}, assuming that N{<=}N{sub f}<2N. This deformation breaks N=2 supersymmetry down to N=1. This theory supports non-Abelian flux tubes (strings) which are stabilized by W. They are referred to as F-term stabilized strings. We focus on the studies of such strings in the vacuum in which N squarks condense, at small {mu}, so that the Z{sub N} strings preserve, in a sense, their Bogomol'nyi-Prasad-Sommerfield nature. The (s)quark massesmore » are assumed to be nondegenerate. We calculate string tensions both in the classical and quantum regimes. Then we translate our results for the tensions in terms of the effective low-energy weighted CP(N{sub f}-1) model on the string world sheet. The bulk {mu} deformation makes this theory N=(0,2) supersymmetric heterotic weighted CP(N{sub f}-1) model in two dimensions. We find the deformation potential on the world sheet. This significantly expands the class of the heterotically deformed CP models emerging on the string world sheet compared to that suggested by Edalati and Tong. Among other things, we show that nonperturbative quantum effects in the bulk theory are exactly reproduced by the quantum effects in the world-sheet theory.« less

Theory and phenomenology of Planckian interacting massive particles as dark matter

NASA Astrophysics Data System (ADS)

Garny, Mathias; Palessandro, Andrea; Sandora, McCullen; Sloth, Martin S.

2018-02-01

Planckian Interacting Dark Matter (PIDM) is a minimal scenario of dark matter assuming only gravitational interactions with the standard model and with only one free parameter, the PIDM mass. PIDM can be successfully produced by gravitational scattering in the thermal plasma of the Standard Model sector after inflation in the PIDM mass range from TeV up to the GUT scale, if the reheating temperature is sufficiently high. The minimal assumption of a GUT scale PIDM mass can be tested in the future by measurements of the primordial tensor-to-scalar ratio. While large primordial tensor modes would be in tension with the QCD axion as dark matter in a large mass range, it would favour the PIDM as a minimal alternative to WIMPs. Here we generalise the previously studied scalar PIDM scenario to the case of fermion, vector and tensor PIDM scenarios, and show that the phenomenology is nearly identical, independent of the spin of the PIDM. We also consider the specific realisation of the PIDM as the Kaluza-Klein excitation of the graviton in orbifold compactifications of string theory, as well as in models of monodromy inflation and in Higgs inflation. Finally we discuss the possibility of indirect detection of PIDM through non-perturbative decay.

Chern-Simons-matter dualities with SO and USp gauge groups

DOE PAGES

Aharony, Ofer; Benini, Francesco; Hsin, Po -Shen; ...

2017-02-14

In the last few years several dualities were found between the low-energy behaviors of Chern-Simons-matter theories with unitary gauge groups coupled to scalars, and similar theories coupled to fermions. In this paper we generalize those dualities to orthogonal and symplectic gauge groups. In particular, we conjecture dualities between SO(N) k Chern-Simons theories coupled to N f real scalars in the fundamental representation, and SO(k)- N+N f /2 coupled to N f real (Majorana) fermions in the fundamental. For N f = 0 these are just level-rank dualities of pure Chern-Simons theories, whose precise form we clarify. They lead us tomore » propose new gapped boundary states of topological insulators and superconductors. As a result, for k = 1 we get an interesting low-energy duality between N f free Majorana fermions and an SO( N) 1 Chern-Simons theory coupled to N f scalar fields (with N f ≤ N-2).« less

Superconductivity from a non-Fermi-liquid metal: Kondo fluctuation mechanism in slave-fermion theory

NASA Astrophysics Data System (ADS)

Kim, Ki-Seok

2010-03-01

We propose Kondo fluctuation mechanism of superconductivity, differentiated from the spin-fluctuation theory as the standard model for unconventional superconductivity in the weak-coupling approach. Based on the U(1) slave-fermion representation of an effective Anderson lattice model, where localized spins are described by the Schwinger boson theory and hybridization or Kondo fluctuations weaken antiferromagnetic correlations of localized spins, we found an antiferromagnetic quantum critical point from an antiferromagnetic metal to a heavy-fermion metal in our recent study. The Kondo-induced antiferromagnetic quantum critical point was shown to be described by both conduction electrons and fermionic holons interacting with critical spin fluctuations given by deconfined bosonic spinons with a spin quantum number 1/2. Surprisingly, such critical modes turned out to be described by the dynamical exponent z=3 , giving rise to the well-known non-Fermi-liquid physics such as the divergent Grüneisen ratio with an exponent 2/3 and temperature-linear resistivity in three dimensions. We find that the z=3 antiferromagnetic quantum critical point becomes unstable against superconductivity, where critical spinon excitations give rise to pairing correlations between conduction electrons and between fermionic holons, respectively, via hybridization fluctuations. Such two kinds of pairing correlations result in multigap unconventional superconductivity around the antiferromagnetic quantum critical point of the slave-fermion theory, where s -wave pairing is not favored generically due to strong correlations. We show that the ratio between each superconducting gap for conduction electrons Δc and holons Δf and the transition temperature Tc is 2Δc/Tc˜9 and 2Δf/Tc˜O(10-1) , remarkably consistent with CeCoIn5 . A fingerprint of the Kondo mechanism is emergence of two kinds of resonance modes in not only spin but also charge fluctuations, where the charge resonance mode at an antiferromagnetic wave vector originates from d -wave pairing of spinless holons. We discuss how the Kondo fluctuation theory differs from the spin-fluctuation approach.

EDITORIAL: Lectures from the European RTN Winter School on Strings, Supergravity and Gauge Theories, CERN, 21 25 January 2008

NASA Astrophysics Data System (ADS)

Derendinger, J.-P.; Orlando, D.; Uranga, A.

2008-11-01

This special issue is devoted to the proceedings of the conference 'RTN Winter School on Strings, Supergravity and Gauge Theories', which took place at CERN, the European Centre for Nuclear Research, in Geneva, Switzerland, on the 21 25 January 2008. This event was organized in the framework of the European Mobility Research and Training Network entitled 'Constituents, Fundamental Forces and Symmetries of the Universe'. It is part of a yearly series of scientific schools, which represents what is by now a well established tradition. The previous ones have been held at SISSA, in Trieste, Italy, in February 2005 and at CERN in January 2006. The next one will again take place at CERN, in February 2009. The school was primarily meant for young doctoral students and postdoctoral researchers working in the area of string theory. It consisted of several general lectures of four hours each, whose notes are published in the present proceedings, and five working group discussion sessions, focused on specific topics of the network research program. It was attended by approximatively 250 participants. The topics of the lectures were chosen to provide an introduction to some of the areas of recent progress, and to the open problems, in string theory. One of the most active areas in string theory in recent years is the AdS/CFT or gauge/gravity correspondence, which proposes the complete equivalence of string theory on (asymptotically) anti-de Sitter spacetimes with gauge theories. The duality relates the weak coupling regime of one system to the strongly coupled regime of the other, and is therefore very non-trivial to test beyond the supersymmetry-protected BPS sector. One of the key ideas to quantitatively match several quantities on both sides is the use of integrability, both in the gauge theory and the string side. The lecture notes by Nick Dorey provide a pedagogical introduction to the fascinating topic of integrability in AdS/CFT. On the string theory side, progress has been limited by the difficulties of quantizing the worldsheet theory in the presence of RR backgrounds. There is increasing hope that these difficulties can be overcome, using the pure spinor formulation of string theory. The lectures by Yaron Oz overview the present status of this proposal. The gauge/gravity correspondence is already leading to important insights into questions of quantum gravity, like the entropy of black holes and its interpretation in terms of microstates. These questions can be addressed in string theory, for certain classes of supersymmetric black holes. The lectures by Vijay Balasubramanian, Jan de Boer, Sheer El-Showk and Ilies Messamah review recent progress in this direction. Throughout the years, formal developments in string theory have systematically led to improved understanding on how it may relate to nature. In this respect, the lectures by Henning Samtleben describe how the formal developments on gauged supergravities can be used to describe compactification vacua in string theory, and their implications for moduli stabilization and supersymmetry breaking. Indeed, softly broken supersymmetry is one of the leading proposals to describe particle physics at the TeV energy range, as described in the lectures by Gian Giudice (not covered in this issue). This connection with TeV scale physics is most appropriate and timely, given that this energy range will shortly become experimentally accessible in the LHC at CERN. The conference was financially supported by the European Commission under contract MRTN-CT-2004-005104 and by CERN. It was jointly organized by the Physics Institute of the University of Neuchâtel and the Theory Unit of the Physics Division of CERN. It is a great pleasure for us to warmly thank the Theory Unit of CERN for its very kind hospitality and for the high quality of the assistance and the infrastructure that it has provided. We also acknowledge helpful administrative assistance from the Physics Institute of the University of Neuchâtel. Special thanks also go to Denis Frank, for his very valuable help in preparing the conference web pages. Group photo

Little string origin of surface defects

NASA Astrophysics Data System (ADS)

Haouzi, Nathan; Schmid, Christian

2017-05-01

We derive a large class of codimension-two defects of 4d \\mathcal{N}=4 Super Yang-Mills (SYM) theory from the (2, 0) little string. The origin of the little string is type IIB theory compactified on an ADE singularity. The defects are D-branes wrapping the 2-cycles of the singularity. We use this construction to make contact with the description of SYM defects due to Gukov and Witten [1]. Furthermore, we provide a geometric perspective on the nilpotent orbit classification of codimension-two defects, and the connection to ADE-type Toda CFT. The only data needed to specify the defects is a set of weights of the algebra obeying certain constraints, which we give explicitly. We highlight the differences between the defect classification in the little string theory and its (2 , 0) CFT limit.

Optical Selection Rule of Excitons in Gapped Chiral Fermion Systems

NASA Astrophysics Data System (ADS)

Zhang, Xiaoou; Shan, Wen-Yu; Xiao, Di

2018-02-01

We show that the exciton optical selection rule in gapped chiral fermion systems is governed by their winding number w , a topological quantity of the Bloch bands. Specifically, in a CN-invariant chiral fermion system, the angular momentum of bright exciton states is given by w ±1 +n N with n being an integer. We demonstrate our theory by proposing two chiral fermion systems capable of hosting dark s -like excitons: gapped surface states of a topological crystalline insulator with C4 rotational symmetry and biased 3 R -stacked MoS2 bilayers. In the latter case, we show that gating can be used to tune the s -like excitons from bright to dark by changing the winding number. Our theory thus provides a pathway to electrical control of optical transitions in two-dimensional material.

Digital Quantum Simulation of Z2 Lattice Gauge Theories with Dynamical Fermionic Matter

NASA Astrophysics Data System (ADS)

Zohar, Erez; Farace, Alessandro; Reznik, Benni; Cirac, J. Ignacio

2017-02-01

We propose a scheme for digital quantum simulation of lattice gauge theories with dynamical fermions. Using a layered optical lattice with ancilla atoms that can move and interact with the other atoms (simulating the physical degrees of freedom), we obtain a stroboscopic dynamics which yields the four-body plaquette interactions, arising in models with (2 +1 ) and higher dimensions, without the use of perturbation theory. As an example we show how to simulate a Z2 model in (2 +1 ) dimensions.

Digital Quantum Simulation of Z_{2} Lattice Gauge Theories with Dynamical Fermionic Matter.

PubMed

Zohar, Erez; Farace, Alessandro; Reznik, Benni; Cirac, J Ignacio

2017-02-17

We propose a scheme for digital quantum simulation of lattice gauge theories with dynamical fermions. Using a layered optical lattice with ancilla atoms that can move and interact with the other atoms (simulating the physical degrees of freedom), we obtain a stroboscopic dynamics which yields the four-body plaquette interactions, arising in models with (2+1) and higher dimensions, without the use of perturbation theory. As an example we show how to simulate a Z_{2} model in (2+1) dimensions.

The Epstein–Glaser causal approach to the light-front QED{sub 4}. II: Vacuum polarization tensor

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

Bufalo, R., E-mail: rodrigo.bufalo@helsinki.fi; Instituto de Física Teórica; Pimentel, B.M., E-mail: pimentel@ift.unesp.br

2014-12-15

In this work we show how to construct the one-loop vacuum polarization for light-front QED{sub 4} in the framework of the perturbative causal theory. Usually, in the canonical approach, it is considered for the fermionic propagator the so-called instantaneous term, but it is known in the literature that this term is controversial because it can be omitted by computational reasons; for instance, by compensation or vanishing by dimensional regularization. In this work we propose a solution to this paradox. First, in the Epstein–Glaser causal theory, it is shown that the fermionic propagator does not have instantaneous term, and with thismore » propagator we calculate the one-loop vacuum polarization, from this calculation it follows the same result as those obtained by the standard approach, but without reclaiming any extra assumptions. Moreover, since the perturbative causal theory is defined in the distributional framework, we can also show the reason behind our obtaining the same result whether we consider or not the instantaneous fermionic propagator term. - Highlights: • We develop the Epstein–Glaser causal approach for light-front field theory. • We evaluate in detail the vacuum polarization at one-loop for the light-front QED. • We discuss the subtle issues of the Instantaneous part of the fermionic propagator in the light-front. • We evaluate the vacuum polarization at one-loop for the light-front QED with the Instantaneous fermionic part.« less

Millicharged dark matter in quantum gravity and string theory.

PubMed

Shiu, Gary; Soler, Pablo; Ye, Fang

2013-06-14

We examine the millicharged dark matter scenario from a string theory perspective. In this scenario, kinetic and mass mixings of the photon with extra U(1) bosons are claimed to give rise to small electric charges, carried by dark matter particles, whose values are determined by continuous parameters of the theory. This seems to contradict folk theorems of quantum gravity that forbid the existence of irrational charges in theories with a single massless gauge field. By considering the underlying structure of the U(1) mass matrix that appears in type II string compactifications, we show that millicharges arise exclusively through kinetic mixing, and require the existence of at least two exactly massless gauge bosons.

Loop Variables in String Theory

NASA Astrophysics Data System (ADS)

Sathiapalan, B.

The loop variable approach is a proposal for a gauge-invariant generalization of the sigma-model renormalization group method of obtaining equations of motion in string theory. The basic guiding principle is space-time gauge invariance rather than world sheet properties. In essence it is a version of Wilson's exact renormalization group equation for the world sheet theory. It involves all the massive modes and is defined with a finite world sheet cutoff, which allows one to go off the mass-shell. On shell the tree amplitudes of string theory are reproduced. The equations are gauge-invariant off shell also. This paper is a self-contained discussion of the loop variable approach as well as its connection with the Wilsonian RG.

New infinite-dimensional hidden symmetries for heterotic string theory

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

Gao Yajun

The symmetry structures of two-dimensional heterotic string theory are studied further. A (2d+n)x(2d+n) matrix complex H-potential is constructed and the field equations are extended into a complex matrix formulation. A pair of Hauser-Ernst-type linear systems are established. Based on these linear systems, explicit formulations of new hidden symmetry transformations for the considered theory are given and then these symmetry transformations are verified to constitute infinite-dimensional Lie algebras: the semidirect product of the Kac-Moody o(d,d+n-circumflex) and Virasoro algebras (without center charges). These results demonstrate that the heterotic string theory under consideration possesses more and richer symmetry structures than previously expected.

Heterotic flux tubes in N=2 supersymmetric QCD with N=1 preserving deformations

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

Shifman, M.; Yung, A.; Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg 188300

2008-06-15

We consider non-Abelian Bogomol'nyi-Prasad-Sommerfield-saturated flux tubes (strings) in N=2 supersymmetric QCD deformed by superpotential terms of a special type breaking N=2 supersymmetry down to N=1. Previously it was believed that world sheet supersymmetry is accidentally enhanced due to the facts that N=(1,1) supersymmetry is automatically elevated up to N=(2,2) on CP(N-1) and, at the same time, there are no N=(0,2) generalizations of the bosonic CP(N-1) model. Edalati and Tong noted that the target space is in fact CP(N-1)xC rather than CP(N-1). This allowed them to suggest a heterotic N=(0,2) sigma model, with the CP(N-1) target space for bosonic fields andmore » an extra right-handed fermion which couples to the fermion fields of the N=(2,2) CP(N-1) model. We derive the heterotic N=(0,2) world sheet model directly from the bulk theory. The relation between the bulk and world sheet deformation parameters we obtain does not coincide with that suggested by Edalati and Tong at large values of the deformation parameter. For polynomial deformation superpotentials in the bulk we find nonpolynomial response in the world sheet model. We find a geometric representation for the heterotic model. Supersymmetry is proven to be spontaneously broken for small deformations (at the quantum level). This confirms Tong's conjecture. A proof valid for large deformations will be presented in the subsequent publication.« less

Dualities in String Cosmology

NASA Astrophysics Data System (ADS)

Meissner, K. A.

We describe in this chapter a set of duality symmetries present in the string-inspired theory of gravity coupled to the dilaton. These dualities are the cornerstones of String Cosmology, which provides alternatives to the usual inflation scenario. The crucial role of Prof. Gabriele Veneziano in the discovery and the development of string dualities is described and emphasized.

The effect of gas and fluid flows on nonlinear lateral vibrations of rotating drill strings

NASA Astrophysics Data System (ADS)

Khajiyeva, Lelya; Kudaibergenov, Askar; Kudaibergenov, Askat

2018-06-01

In this work we develop nonlinear mathematical models describing coupled lateral vibrations of a rotating drill string under the effect of external supersonic gas and internal fluid flows. An axial compressive load and a torque also affect the drill string. The mathematical models are derived by the use of Novozhilov's nonlinear theory of elasticity with implementation of Hamilton's variation principle. Expressions for the gas flow pressure are determined according to the piston theory. The fluid flow is considered as added mass inside the curved tube of the drill string. Using an algorithm developed in the Mathematica computation program on the basis of the Galerkin approach and the stiffness switching method the numerical solution of the obtained approximate differential equations is found. Influences of the external loads, drill string angular speed of rotation, parameters of the gas and fluid flows on the drill string vibrations are shown.

Strings from massive higher spins: the asymptotic uniqueness of the Veneziano amplitude

NASA Astrophysics Data System (ADS)

Caron-Huot, Simon; Komargodski, Zohar; Sever, Amit; Zhiboedov, Alexander

2017-10-01

We consider weakly coupled theories of massive higher-spin particles. This class of models includes, for instance, tree-level String Theory and Large-N Yang-Mills theory. The S-matrix in such theories is a meromorphic function obeying unitarity and crossing symmetry. We discuss the (unphysical) regime s, t ≫ 1, in which we expect the amplitude to be universal and exponentially large. We develop methods to study this regime and show that the amplitude necessarily coincides with the Veneziano amplitude there. In particular, this implies that the leading Regge trajectory, j( t), is asymptotically linear in Yang-Mills theory. Further, our analysis shows that any such theory of higherspin particles has stringy excitations and infinitely many asymptotically parallel subleading trajectories. More generally, we argue that, under some assumptions, any theory with at least one higher-spin particle must have strings.

Hidden Symmetries in String Theory

NASA Astrophysics Data System (ADS)

Chervonyi, Iurii

In this thesis we study hidden symmetries within the framework of string theory. Symmetries play a very important role in physics: they lead to drastic simplifications, which allow one to compute various physical quantities without relying on perturbative techniques. There are two kinds of hidden symmetries investigated in this work: the first type is associated with dynamics of quantum fields and the second type is related to integrability of strings on various backgrounds. Integrability is a remarkable property of some theories that allows one to determine all dynamical properties of the system using purely analytical methods. The goals of this thesis are twofold: extension of hidden symmetries known in General Relativity to stringy backgrounds in higher dimensions and construction of new integrable string theories. In the context of the first goal we study hidden symmetries of stringy backgrounds, with and without supersymmetry. For supersymmetric geometries produced by D-branes we identify the backgrounds with solvable equations for geodesics, which can potentially give rise to integrable string theories. Relaxing the requirement of supersymmetry, we also study charged black holes in higher dimensions and identify their hidden symmetries encoded in so-called Killing(-Yano) tensors. We construct the explicit form of the Killing(-Yano) tensors for the charged rotating black hole in arbitrary number of dimensions, study behavior of such tensors under string dualities, and use the analysis of hidden symmetries to explain why exact solutions for black rings (black holes with non-spherical event horizons) in more than five dimensions remain elusive. As a byproduct we identify the standard parameterization of AdSp x Sq backgrounds with elliptic coordinates on a flat base. The second goal of this work is construction of new integrable string theories by applying continuous deformations of known examples. We use the recent developments called (generalized) lambda-deformation to construct new integrable backgrounds depending on several continuous parameters and study analytical properties of the such deformations.

Spectral Properties of Composite Excitations in the t-J Model

NASA Astrophysics Data System (ADS)

Otaki, Takashi; Yahagi, Yuta; Matsueda, Hiroaki

2017-08-01

In quantum many-body systems, the equation of motion for a simple fermionic operator does not close, and higher-order processes induce composite operators dressed with several types of nonlocal quantum fluctuation. We systematically examine the spectral properties of these composite excitations in the t-J model in one spatial dimension by both numerical and theoretical approaches. Of particular interest, with the help of the Bethe ansatz for the large-U Hubbard model, is the classification of which composite excitations are due to the string excitation, which is usually hidden in the single-particle spectrum, as well as the spinon and holon branches. We examine how the mixing between the spinon and string excitations is prohibited in terms of the composite operator method. Owing to the dimensionality independent nature of the present approach, we discuss the implications of the mixing in close connection with the pseudogap in high-Tc cuprates.

Renormalized Polyakov loop in the deconfined phase of SU(N) gauge theory and gauge-string duality.

PubMed

Andreev, Oleg

2009-05-29

We use gauge-string duality to analytically evaluate the renormalized Polyakov loop in pure Yang-Mills theories. For SU(3), the result is in quite good agreement with lattice simulations for a broad temperature range.

Localized gravity in string theory.

PubMed

Karch, A; Randall, L

2001-08-06

We propose a string realization of the AdS4 brane in AdS5 that is known to localize gravity. Our theory is M D5 branes in the near horizon geometry of N D3 branes, where M and N are appropriately tuned.

Six-dimensional regularization of chiral gauge theories

NASA Astrophysics Data System (ADS)

Fukaya, Hidenori; Onogi, Tetsuya; Yamamoto, Shota; Yamamura, Ryo

2017-03-01

We propose a regularization of four-dimensional chiral gauge theories using six-dimensional Dirac fermions. In our formulation, we consider two different mass terms having domain-wall profiles in the fifth and the sixth directions, respectively. A Weyl fermion appears as a localized mode at the junction of two different domain walls. One domain wall naturally exhibits the Stora-Zumino chain of the anomaly descent equations, starting from the axial U(1) anomaly in six dimensions to the gauge anomaly in four dimensions. Another domain wall implies a similar inflow of the global anomalies. The anomaly-free condition is equivalent to requiring that the axial U(1) anomaly and the parity anomaly are canceled among the six-dimensional Dirac fermions. Since our formulation is based on a massive vector-like fermion determinant, a nonperturbative regularization will be possible on a lattice. Putting the gauge field at the four-dimensional junction and extending it to the bulk using the Yang-Mills gradient flow, as recently proposed by Grabowska and Kaplan, we define the four-dimensional path integral of the target chiral gauge theory.

Five-dimensional gauge theory and compactification on a torus

NASA Astrophysics Data System (ADS)

Haghighat, Babak; Vandoren, Stefan

2011-09-01

We study five-dimensional minimally supersymmetric gauge theory compactified on a torus down to three dimensions, and its embedding into string/M-theory using geometric engineering. The moduli space on the Coulomb branch is hyperkähler equipped with a metric with modular transformation properties. We determine the one-loop corrections to the metric and show that they can be interpreted as worldsheet and D1-brane instantons in type IIB string theory. Furthermore, we analyze instanton corrections coming from the solitonic BPS magnetic string wrapped over the torus. In particular, we show how to compute the path-integral for the zero-modes from the partition function of the M5 brane, or, using a 2d/4d correspondence, from the partition function of N=4 SYM theory on a Hirzebruch surface.

Cosmology of the closed string tachyon

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

Swanson, Ian

2008-09-15

The spacetime physics of bulk closed string tachyon condensation is studied at the level of a two-derivative effective action. We derive the unique perturbative tachyon potential consistent with a full class of linearized tachyonic deformations of supercritical string theory. The solutions of interest deform a general linear dilaton background by the insertion of purely exponential tachyon vertex operators. In spacetime, the evolution of the tachyon drives an accelerated contraction of the universe and, absent higher-order corrections, the theory collapses to a cosmological singularity in finite time, at arbitrarily weak string coupling. When the tachyon exhibits a null symmetry, the worldsheetmore » dynamics is known to be exact and well defined at tree level. We prove that if the two-derivative effective action is free of nongravitational singularities, higher-order corrections always resolve the spacetime curvature singularity of the null tachyon. The resulting theory provides an explicit mechanism by which tachyon condensation can generate or terminate the flow of cosmological time in string theory. Additional particular solutions can resolve an initial singularity with a tachyonic phase at weak coupling, or yield solitonic configurations that localize the universe along spatial directions.« less

Purely cubic action for string field theory

NASA Technical Reports Server (NTRS)

Horowitz, G. T.; Lykken, J.; Rohm, R.; Strominger, A.

1986-01-01

It is shown that Witten's (1986) open-bosonic-string field-theory action and a closed-string analog can be written as a purely cubic interaction term. The conventional form of the action arises by expansion around particular solutions of the classical equations of motion. The explicit background dependence of the conventional action via the Becchi-Rouet-Stora-Tyutin operator is eliminated in the cubic formulation. A closed-form expression is found for the full nonlinear gauge-transformation law.

Non-Abelian string and particle braiding in topological order: Modular SL (3 ,Z ) representation and (3 +1 ) -dimensional twisted gauge theory

NASA Astrophysics Data System (ADS)

Wang, Juven C.; Wen, Xiao-Gang

2015-01-01

String and particle braiding statistics are examined in a class of topological orders described by discrete gauge theories with a gauge group G and a 4-cocycle twist ω4 of G 's cohomology group H4(G ,R /Z ) in three-dimensional space and one-dimensional time (3 +1 D ) . We establish the topological spin and the spin-statistics relation for the closed strings and their multistring braiding statistics. The 3 +1 D twisted gauge theory can be characterized by a representation of a modular transformation group, SL (3 ,Z ) . We express the SL (3 ,Z ) generators Sx y z and Tx y in terms of the gauge group G and the 4-cocycle ω4. As we compactify one of the spatial directions z into a compact circle with a gauge flux b inserted, we can use the generators Sx y and Tx y of an SL (2 ,Z ) subgroup to study the dimensional reduction of the 3D topological order C3 D to a direct sum of degenerate states of 2D topological orders Cb2 D in different flux b sectors: C3 D=⊕bCb2 D . The 2D topological orders Cb2 D are described by 2D gauge theories of the group G twisted by the 3-cocycle ω3 (b ), dimensionally reduced from the 4-cocycle ω4. We show that the SL (2 ,Z ) generators, Sx y and Tx y, fully encode a particular type of three-string braiding statistics with a pattern that is the connected sum of two Hopf links. With certain 4-cocycle twists, we discover that, by threading a third string through two-string unlink into a three-string Hopf-link configuration, Abelian two-string braiding statistics is promoted to non-Abelian three-string braiding statistics.

Deforming baryons into confining strings

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

Hartnoll, Sean A.; Portugues, Ruben

2004-09-15

We find explicit probe D3-brane solutions in the infrared of the Maldacena-Nunez background. The solutions describe deformed baryon vertices: q external quarks are separated in spacetime from the remaining N-q. As the separation is taken to infinity we recover known solutions describing infinite confining strings in N=1 gauge theory. We present results for the mass of finite confining strings as a function of length. We also find probe D2-brane solutions in a confining type IIA geometry, the reduction of a G{sub 2} holonomy M theory background. The relation between these deformed baryons and confining strings is not as straightforward.

String unification scale and the hyper-charge Kac-Moody level in the non-supersymmetric standard model

NASA Astrophysics Data System (ADS)

Cho, Gi-Chol; Hagiwara, Kaoru

1998-02-01

The string theory predicts the unification of the gauge couplings and gravity. The minimal supersymmetric Standard Model, however, gives the unification scale ~2x1016 GeV which is significantly smaller than the string scale ~5x1017 GeV of the weak coupling heterotic string theory. We study the unification scale of the non-supersymmetric minimal Standard Model quantitatively at the two-loop level. We find that the unification scale should be at most ~4x1016 GeV and the desired Kac-Moody level of the hyper-charge coupling should be 1.33<~kY<~1.35.

String Theory Methods for Condensed Matter Physics

NASA Astrophysics Data System (ADS)

Nastase, Horatiu

2017-09-01

Preface; Acknowledgments; Introduction; Part I. Condensed Matter Models and Problems: 1. Lightning review of statistical mechanics, thermodynamics, phases and phase transitions; 2. Magnetism in solids; 3. Electrons in solids: Fermi gas vs. Fermi liquid; 4. Bosonic quasi-particles: phonons and plasmons; 5. Spin-charge separation in 1+1 dimensional solids: spinons and holons; 6. The Ising model and the Heisenberg spin chain; 7. Spin chains and integrable systems; 8. The thermodynamic Bethe ansatz; 9. Conformal field theories and quantum phase transitions; 10. Classical vs. quantum Hall effect; 11. Superconductivity: Landau-Ginzburg, London and BCS; 12. Topology and statistics: Berry and Chern-Simons, anyons and nonabelions; 13. Insulators; 14. The Kondo effect and the Kondo problem; 15. Hydrodynamics and transport properties: from Boltzmann to Navier-Stokes; Part II. Elements of General Relativity and String Theory: 16. The Einstein equation and the Schwarzschild solution; 17. The Reissner-Nordstrom and Kerr-Newman solutions and thermodynamic properties of black holes; 18. Extra dimensions and Kaluza-Klein; 19. Electromagnetism and gravity in various dimensions. Consistent truncations; 20. Gravity plus matter: black holes and p-branes in various dimensions; 21. Weak/strong coupling dualities in 1+1, 2+1, 3+1 and d+1 dimensions; 22. The relativistic point particle and the relativistic string; 23. Lightcone strings and quantization; 24. D-branes and gauge fields; 25. Electromagnetic fields on D-branes. Supersymmetry and N = 4 SYM. T-duality of closed strings; 26. Dualities and M theory; 27. The AdS/CFT correspondence: definition and motivation; Part III. Applying String Theory to Condensed Matter Problems: 28. The pp wave correspondence: string Hamiltonian from N = 4 SYM; 29. Spin chains from N = 4 SYM; 30. The Bethe ansatz: Bethe strings from classical strings in AdS; 31. Integrability and AdS/CFT; 32. AdS/CFT phenomenology: Lifshitz, Galilean and Schrodinger symmetries and their gravity duals; 33. Finite temperature and black holes; 34. Hot plasma equilibrium thermodynamics: entropy, charge density and chemical potential of strongly coupled theories; 35. Spectral functions and transport properties; 36. Dynamic and nonequilibrium properties of plasmas: electric transport, Langevin diffusion and thermalization via black hole quasi-normal modes; 37. The holographic superconductor; 38. The fluid-gravity correspondence: conformal relativistic fluids from black hole horizons; 39. Nonrelativistic fluids: from Einstein to Navier-Stokes and back; Part IV. Advanced Applications: 40. Fermi gas and liquid in AdS/CFT; 41. Quantum Hall effect from string theory; 42. Quantum critical systems and AdS/CFT; 43. Particle-vortex duality and ABJM vs. AdS4 X CP3 duality; 44. Topology and non-standard statistics from AdS/CFT; 45. DBI scalar model for QGP/black hole hydro- and thermo-dynamics; 46. Holographic entanglement entropy in condensed matter; 47. Holographic insulators; 48. Holographic strange metals and the Kondo problem; References; Index.

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

Park, I.Y.; Tirziu, A.; Tseytlin, A.A.

We consider circular strings rotating with equal spins S{sub 1}=S{sub 2}=S in two orthogonal planes in AdS{sub 5} and suggest that they may be dual to long gauge-theory operators built out of self-dual components of gauge field strength. As was found in hep-th/0404187, the one-loop anomalous dimensions of the such gauge-theory operators are described by an antiferromagnetic XXX{sub 1} spin chain and scale linearly with length L>>1. We find that in the case of rigid rotating string both the classical energy E{sub 0} and the 1-loop string correction E{sub 1} depend linearly on the spin S (within the stability regionmore » of the solution). This supports the identification of the rigid rotating string with the gauge-theory operator corresponding to the maximal-spin (ferromagnetic) state of the XXX{sub 1} spin chain. The energy of more general rotating and pulsating strings also happens to scale linearly with both the spin and the oscillation number. Such solutions should be dual to other lower-spin states of the spin chain, with the antiferromagnetic ground state presumably corresponding to the string pulsating in two planes with no rotation.« less

String-theoretic breakdown of effective field theory near black hole horizons

NASA Astrophysics Data System (ADS)

Dodelson, Matthew; Silverstein, Eva

2017-09-01

We investigate the validity of the equivalence principle near horizons in string theory, analyzing the breakdown of effective field theory caused by longitudinal string spreading effects. An experiment is set up where a detector is thrown into a black hole a long time after an early infalling string. Light cone gauge calculations, taken at face value, indicate a detectable level of root-mean-square longitudinal spreading of the initial string as measured by the late infaller. This results from the large relative boost between the string and detector in the near-horizon region, which develops automatically despite their modest initial energies outside the black hole and the weak curvature in the geometry. We subject this scenario to basic consistency checks, using these to obtain a relatively conservative criterion for its detectability. In a companion paper, we exhibit longitudinal nonlocality in well-defined gauge-invariant S-matrix calculations, obtaining results consistent with the predicted spreading albeit not in a direct analog of the black hole process. We discuss applications of this effect to the firewall paradox, and estimate the time and distance scales it predicts for new physics near black hole and cosmological horizons.

Second quantization of a covariant relativistic spacetime string in Steuckelberg-Horwitz-Piron theory

NASA Astrophysics Data System (ADS)

Suleymanov, Michael; Horwitz, Lawrence; Yahalom, Asher

2017-06-01

A relativistic 4D string is described in the framework of the covariant quantum theory first introduced by Stueckelberg [ Helv. Phys. Acta 14, 588 (1941)], and further developed by Horwitz and Piron [ Helv. Phys. Acta 46, 316 (1973)], and discussed at length in the book of Horwitz [Relativistic Quantum Mechanics, Springer (2015)]. We describe the space-time string using the solutions of relativistic harmonic oscillator [ J. Math. Phys. 30, 66 (1989)]. We first study the problem of the discrete string, both classically and quantum mechanically, and then turn to a study of the continuum limit, which contains a basically new formalism for the quantization of an extended system. The mass and energy spectrum are derived. Some comparison is made with known string models.

Pinching parameters for open (super) strings

NASA Astrophysics Data System (ADS)

Playle, Sam; Sciuto, Stefano

2018-02-01

We present an approach to the parametrization of (super) Schottky space obtained by sewing together three-punctured discs with strips. Different cubic ribbon graphs classify distinct sets of pinching parameters; we show how they are mapped onto each other. The parametrization is particularly well-suited to describing the region within (super) moduli space where open bosonic or Neveu-Schwarz string propagators become very long and thin, which dominates the IR behaviour of string theories. We show how worldsheet objects such as the Green's function converge to graph theoretic objects such as the Symanzik polynomials in the α ' → 0 limit, allowing us to see how string theory reproduces the sum over Feynman graphs. The (super) string measure takes on a simple and elegant form when expressed in terms of these parameters.

Mass and angular momentum of black holes in low-energy heterotic string theory

NASA Astrophysics Data System (ADS)

Peng, Jun-Jin

2016-04-01

We investigate conserved charges in the low-energy effective field theory describing heterotic string theory. Starting with a general Lagrangian that consists of a metric, a scalar field, a vector gauge field, together with a two-form potential, we derive off-shell Noether potentials of the Lagrangian and generalize the Abbott-Deser-Tekin (ADT) formalism to the off-shell level by establishing one-to-one correspondence between the ADT potential and the off-shell Noether potential. It is proved that the off-shell generalized ADT formalism is conformally invariant. Then, we apply the formulation to compute mass and angular momentum of the four-dimensional Kerr-Sen black hole and the five-dimensional rotating charged black string in the string frame without a necessity to transform the metrics into the Einstein frame.

Ambitwistor formulations of R 2 gravity and ( DF)2 gauge theories

NASA Astrophysics Data System (ADS)

Azevedo, Thales; Engelund, Oluf Tang

2017-11-01

We consider D-dimensional amplitudes in R 2 gravities (conformal gravity in D = 4) and in the recently introduced ( DF)2 gauge theory, from the perspective of the CHY formulae and ambitwistor string theory. These theories are related through the BCJ double-copy construction, and the ( DF)2 gauge theory obeys color-kinematics duality. We work out the worldsheet details of these theories and show that they admit a formulation as integrals on the support of the scattering equations, or alternatively, as ambitwistor string theories. For gravity, this generalizes the work done by Berkovits and Witten on conformal gravity to D dimensions. The ambitwistor is also interpreted as a D-dimensional generalization of Witten's twistor string (SYM + conformal supergravity). As part of our ambitwistor investigation, we discover another ( DF)2 gauge theory containing a photon that couples to Einstein gravity. This theory can provide an alternative KLT description of Einstein gravity compared to the usual Yang-Mills squared.

Birth of the Universe from the Multiverse

NASA Astrophysics Data System (ADS)

Mersini-Houghton, Laura

2015-01-01

Compactification of extra dimensions in string theory leads to a vast number of (3+1) dimensional worlds, (about 10500 so far), coined the landscape. At the time of the discovery of the landscape, the question which one of these worlds is our universe seemed hopeless. Many argued that the vastness of the landscape undermines the very foundations of string theory for two reasons: (i) the theory seemed unfalsifiable since for every observation we could find a matching world on the landscape; (ii) the method advocated at the time for making sense of this landscape was the anthropic principle. The former objection implied string theory can not be scientific. The latter concern is that anthropics do not help scientific inquiry and rigor but rather it may seem to push some version of creationism to the next level. For these reasons the whole field of string theory and also, of cosmology that relied on it for answers about fundamental questions such as the origins of the universe, seemed to be in deep crisis at the beginning of the millenia...

Fermion Cooper pairing with unequal masses: Standard field theory approach

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

He Lianyi; Jin Meng; Zhuang Pengfei

Fermion Cooper pairing with unequal masses is investigated in a standard field theory approach. We derived the superfluid density and Meissner mass squared of the U(1) gauge field in a general two-species model and found that the often used proportional relation between the two quantities is broken when the fermion masses are unequal. In the weak-coupling region, the superfluid density is always negative but the Meissner mass squared becomes mostly positive when the mass ratio between the pairing fermions is large enough. We established a proper momentum configuration of the LOFF pairing with unequal masses and showed that the LOFFmore » state is energetically favored due to the negative superfluid density. The single-plane-wave LOFF state is physically equivalent to an anisotropic state with a spontaneously generated superflow. The extension to a finite-range interaction is briefly discussed.« less

Entanglement negativity bounds for fermionic Gaussian states

NASA Astrophysics Data System (ADS)

Eisert, Jens; Eisler, Viktor; Zimborás, Zoltán

2018-04-01

The entanglement negativity is a versatile measure of entanglement that has numerous applications in quantum information and in condensed matter theory. It can not only efficiently be computed in the Hilbert space dimension, but for noninteracting bosonic systems, one can compute the negativity efficiently in the number of modes. However, such an efficient computation does not carry over to the fermionic realm, the ultimate reason for this being that the partial transpose of a fermionic Gaussian state is no longer Gaussian. To provide a remedy for this state of affairs, in this work, we introduce efficiently computable and rigorous upper and lower bounds to the negativity, making use of techniques of semidefinite programming, building upon the Lagrangian formulation of fermionic linear optics, and exploiting suitable products of Gaussian operators. We discuss examples in quantum many-body theory and hint at applications in the study of topological properties at finite temperature.

Quantization of set theory and generalization of the fermion algebra

NASA Astrophysics Data System (ADS)

Arik, M.; Tekin, S. C.

2002-05-01

The quantum states of a d-dimensional fermion algebra are in one to one correspondence with the subsets of a d-element universal set. In this paper we use this set theoretical motivation to construct a one-parameter deformation of the fermion algebra and extend it to a d-dimensional generalization which is invariant under the group U(d). This discrete fermionic oscillator system is extended to the continuous case. We also show that the q-deformation of these systems is related to supercovariant q-oscillators.

Instantons and Massless Fermions in Two Dimensions

DOE R&D Accomplishments Database

Callan, C. G. Jr.; Dashen, R.; Gross, D. J.

1977-05-01

The role of instantons in the breakdown of chiral U(N) symmetry is studied in a two dimensional model. Chiral U(1) is always destroyed by the axial vector anomaly. For N = 2 chiral SU(N) is also spontaneously broken yielding massive fermions and three (decoupled) Goldstone bosons. For N greater than or equal to 3 the fermions remain massless. Realistic four dimensional theories are believed to behave in a similar way but the critical N above which the fermions cease to be massive is not known in four dimensions.

Strings on complex multiplication tori and rational conformal field theory with matrix level

NASA Astrophysics Data System (ADS)

Nassar, Ali

Conformal invariance in two dimensions is a powerful symmetry. Two-dimensional quantum field theories which enjoy conformal invariance, i.e., conformal field theories (CFTs) are of great interest in both physics and mathematics. CFTs describe the dynamics of the world sheet in string theory where conformal symmetry arises as a remnant of reparametrization invariance of the world-sheet coordinates. In statistical mechanics, CFTs describe the critical points of second order phase transitions. On the mathematics side, conformal symmetry gives rise to infinite dimensional chiral algebras like the Virasoro algebra or extensions thereof. This gave rise to the study of vertex operator algebras (VOAs) which is an interesting branch of mathematics. Rational conformal theories are a simple class of CFTs characterized by a finite number of representations of an underlying chiral algebra. The chiral algebra leads to a set of Ward identities which gives a complete non-perturbative solution of the RCFT. Identifying the chiral algebra of an RCFT is a very important step in solving it. Particularly interesting RCFTs are the ones which arise from the compactification of string theory as sigma-models on a target manifold M. At generic values of the geometric moduli of M, the corresponding CFT is not rational. Rationality can arise at particular values of the moduli of M. At these special values of the moduli, the chiral algebra is extended. This interplay between the geometric picture and the algebraic description encoded in the chiral algebra makes CFTs/RCFTs a perfect link between physics and mathematics. It is always useful to find a geometric interpretation of a chiral algebra in terms of a sigma-model on some target manifold M. Then the next step is to figure out the conditions on the geometric moduli of M which gives a RCFT. In this thesis, we limit ourselves to the simplest class of string compactifications, i.e., strings on tori. As Gukov and Vafa proved, rationality selects the complex-multiplication tori. On the other hand, the study of the matrix-level affine algebra Um,K is motivated by conformal field theory and the fractional quantum Hall effect. Gannon completed the classification of U m,K modular-invariant partition functions. Here we connect the algebra U2,K to strings on 2-tori describable by rational conformal field theories. We point out that the rational conformal field theories describing strings on complex-multiplication tori have characters and partition functions identical to those of the matrix-level algebra Um,K. This connection makes obvious that the rational theories are dense in the moduli space of strings on Tm, and may prove useful in other ways.

Quantum-critical theory of the spin-fermion model and its application to cuprates: normal state analysis

NASA Astrophysics Data System (ADS)

Abanov, Ar.; Chubukov, Andrey V.; Schmalian, J.

2003-03-01

We present the full analysis of the normal state properties of the spin-fermion model near the antiferromagnetic instability in two dimensions. The model describes low-energy fermions interacting with their own collective spin fluctuations, which soften at the antiferromagnetic transition. We argue that in 2D, the system has two typical energies-an effective spin-fermion interaction bar g and an energy ysf below which the system behaves as a Fermi liquid. The ratio of the two determines the dimensionless coupling constant for spin-fermion interaction lambda (2) alpha /line g /omega _{sf} . We show that u scales with the spin correlation length and diverges at criticality. This divergence implies that the conventional perturbative expansion breaks down. We develop a novel approach to the problem-the expansion in either the inverse number of hot spots in the Brillouin zone, or the inverse number of fermionic flavours-which allows us to explicitly account for all terms which diverge as powers of u, and treat the remaining, O(logu) terms in the RG formalism. We apply this technique to study the properties of the spin-fermion model in various frequency and temperature regimes. We present the results for the fermionic spectral function, spin susceptibility, optical conductivity and other observables. We compare our results in detail with the normal state data for the cuprates, and argue that the spin-fermion model is capable of explaining the anomalous normal state properties of the high Tc materials. We also show that the conventional Ӓ theory of the quantum-critical behaviour is inapplicable in 2D due to the singularity of the Ӓ vertex.