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Abelian Chern-Simons field theory and anyon equation on a cylinder: We present the anyon equation on a cylinder and in an infinite potential wall from the abelian Chern-Simons theory coupled to non-relativistic matter field by obtaining the effective hamiltonian through the canonical transformation method used for the ...
hep-th
DeWitt-Virasoro construction in tensor representations: We generalize the DeWitt-Virasoro (DWV) construction of arXiv:0912.3987 [hep-th] to tensor representations of higher ranks. A rank-$n$ tensor state, which is by itself coordinate invariant, is expanded in terms of position eigenstates that transform as tensors of ...
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A Note About Localized Photons on the Brane: A first order formulation for the Maxwell field in five dimensions is dimensionally reduced using the Randall-Sundrum mechanism. We will see that massive photons can not be localized on the brane.
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Quantum Field, Thermodynamics and Black Hole on Coherent State Representation of Fuzzy Space: We first use the coherent state formalism of fuzzy space to show that the fuzziness will eliminate point-like structure of a particle in favor of smeared object, which is an exponential decay function in contrast to the Gaus...
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Conformal Anomaly and Off-Shell Extensions of Gravity: The gauge dependence of the conformal anomaly for spin 3/2 and spin 2 fields in non-conformal supergravities has been a long standing puzzle. In this Letter we argue that the `correct' gauge choice is the one that follows from requiring all terms that would imply a...
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Non-Hermitian Lagrangian for quasi-relativistic fermions: We present a Lorentz-symmetry violating Lagrangian for free fermions, which is local but not Hermitian, whereas the corresponding Hamiltonian is Hermitian but not local. A specific feature of the model is that the dispersion relation is relativistic in both the ...
hep-th
Wedge-Local Quantum Fields and Noncommutative Minkowski Space: Within the setting of a recently proposed model of quantum fields on noncommutative Minkowski spacetime, the consequences of the consistent application of the proper, untwisted Poincare group as the symmetry group are investigated. The emergent model contai...
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Large N and double scaling limits in two dimensions: Recently, the author has constructed a series of four dimensional non-critical string theories with eight supercharges, dual to theories of light electric and magnetic charges, for which exact formulas for the central charge of the space-time supersymmetry algebra as...
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The Algebra of Chern-Simons Classes and the Poisson Bracket on it: Developing ideas based on combinatorial formulas for characteristic classes we introduce the algebra modeling secondary characteristic classes associated to $N$ connections. Certain elements of the algebra correspond to the ordinary and secondary charac...
hep-th
Non supersymmetric femion boson symmetry: In this work we present symmetry transformations relating bosons to fermions which cannot be represented as a supersymmetric algebra. We present a symmetry transformation relating a complex scalar and a fermion in four dimensions and construct a theory defined by an action that...
hep-th
Noncommutative hamiltonian formalism for noncommutative gravity: We present a covariant canonical formalism for noncommutative gravity, and in general for noncommutative geometric theories defined via a twisted $\star$-wedge product between forms. Noether theorems are generalized to the noncommutative setting, and gaug...
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Curiosities on Free Fock Spaces: We consider some curious aspects of single-species free Fock spaces, such as novel bosonization and fermionization formulae and relations to various physical properties of bosonic particles. We comment on generalizations of these properties to physically more interesting many-species fr...
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One-loop analysis with nonlocal boundary conditions: In the eighties, Schroder studied a quantum mechanical model where the stationary states of Schrodinger's equation obey nonlocal boundary conditions on a circle in the plane. For such a problem, we perform a detailed one-loop calculation for three choices of the kern...
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Massless Thirring fermion fields in the boson field representation: We show that the boson field representation of the massless fermion fields, suggested by Morchio, Pierotti and Strocchi in J. Math. Phys. 33, 777 (1992) for the operator solution of the massless Thirring model, agrees completely with the existence of t...
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Supergravity EFTs and swampland constraints: In these proceedings, we review recent progress in analyzing the behavior of lower-dimensional supergravity theories when combined with swampland conjectures. We show that within supergravity the effectiveness and usefulness of swampland conjectures gets amplified, existing ...
hep-th
The All-Loop Integrand For Scattering Amplitudes in Planar N=4 SYM: We give an explicit recursive formula for the all L-loop integrand for scattering amplitudes in N=4 SYM in the planar limit, manifesting the full Yangian symmetry of the theory. This generalizes the BCFW recursion relation for tree amplitudes to all lo...
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The Quantum Effective Action, Wave Functions and Yang-Mills (2+1): We explore the relationship between the quantum effective action and the ground state (and excited state) wave functions of a field theory. Applied to the Yang-Mills theory in 2+1 dimensions, we find the leading terms of the effective action from the gr...
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A modification of the 10d superparticle action inspired by the Gupta-Bleuler quantization scheme method: We reconsider the issue of the existence of a complex structure in the Gupta-Bleuler quantization scheme. We prove an existence theorem for the complex structure associated with the $d=10$ Casalbuoni-Brink-Schwarz...
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An analytic study on the excited states of holographic superconductors: Based on the Sturm-Liouville eigenvalue problem, we develop a general analytic technique to investigate the excited states of the holographic superconductors. By including more higher order terms in the expansion of the trial function, we observe t...
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Including four-gluon interactions into Landau and maximally-Abelian gauge Dyson-Schwinger studies: In Dyson-Schwinger studies of the Yang-Mills propagators the four-gluon interaction has been usually neglected due to the related technical difficulties with the associated two-loop terms and especially their renormaliz...
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String solutions in Chern-Simons-Higgs model coupled to an axion: We study a d=2+1 dimensional Chern-Simons gauge theory coupled to a Higgs scalar and an axion field, finding the form of the potential that allows the existence of selfdual equations and the corresponding Bogomolny bound for the energy of static configur...
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The B-field soft theorem and its unification with the graviton and dilaton: In theories of Einstein gravity coupled with a dilaton and a two-form, a soft theorem for the two-form, known as the Kalb-Ramond B-field, has so far been missing. In this work we fill the gap, and in turn formulate a unified soft theorem vali...
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Particle astrophysics in nonlinear supersymmetric general relativity: An explanation of relations between the large scale structure of the universe and the tiny scale structure of the particle physics, e.g. the observed mysterious relation between the (dark) energy density and the dark matter of the universe and the ne...
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Infinite statistics, symmetry breaking and combinatorial hierarchy: The physics of symmetry breaking in theories with strongly interacting quanta obeying infinite (quantum Boltzmann) statistics known as quons is discussed. The picture of Bose/Fermi particles as low energy excitations over nontrivial quon condensate is ...
hep-th
Quantization of Fayet-Iliopoulos Parameters in Supergravity: In this short note we discuss quantization of the Fayet-Iliopoulos parameter in supergravity theories. We argue that in supergravity, the Fayet-Iliopoulos parameter determines a lift of the group action to a line bundle, and such lifts are quantized. Just as ...
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The Casimir effect for pistons with transmittal boundary conditions: This work focuses on the analysis of the Casimir effect for pistons subject to transmittal boundary conditions. In particular we consider, as piston configuration, a direct product manifold of the type $I\times N$ where $I$ is a closed interval of the...
hep-th
High Temperature Effects on Compactlike Structures: In this work we investigate the transition from kinks to compactons at high temperatures. We deal with a family of models, described by a real scalar field with standard kinematics, controlled by a single parameter, real and positive. The family of models supports kin...
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Arbitrary Superspin Massive Superparticles: We propose the action for a massive $N$-extended superparticle with a pure (half)integer superspin $Y,~Y = 0, 1/2, 1, 3/2, \ldots$. Regardless of the superspin value, the configuration space is ${\Bbb R}^{4|4N} \times S^2$, where $S^2$ corresponds to spinning degrees of freed...
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Supersymmetric Yang-Mills Theories in $D\ge 12$: We present supersymmetric Yang-Mills theories in arbitrary even dimensions with the signature (9+m,1+m) where $m=0,1,2,...$ beyond ten-dimensions up to infinity. This formulation utilizes null-vectors and is a generalization of our previous work in 10+2 dimensions to arb...
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Charged Open Membrane Solutions On A Manifold With Boundary: Explicit open single and multi-membrane solutions of the low energy limit of M-theory on the orbifold $R^{10}\times S^1/Z_2$ are presented. This low energy action is described by an 11-dimensional supergravity action coupled to two $E_8$ super Yang-Mills fiel...
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Quantum gravity on a torus: Causal Dynamical Triangulations (CDT) is a non-perturbative lattice approach to quantum gravity where one assumes space-time foliation into spatial hyper-surfaces of fixed topology. Most of the CDT results were obtained for the spatial topology of the 3-sphere. It was shown that CDT has rich...
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Non-geometric heterotic backgrounds and 6D SCFTs/LSTs: We study ${\mathcal N}=(1,0)$ six-dimensional theories living on defects of non-geometric backgrounds of the $E_8\times E_8$ and the $\text{Spin}(32)/{\mathbb Z}_2$ heterotic strings. Such configurations can be analyzed by dualizing to F-theory on elliptic K3-fiber...
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Dyson's Classification And Real Division Superalgebras: It is well-known that unitary irreducible representations of groups can be usefully classified in a 3-fold classification scheme: Real, Complex, Quaternionic. In 1962 Freeman Dyson pointed out that there is an analogous 10-fold classification of irreducible repres...
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Exact conditions for Quasi-normal modes of extremal M5-branes and Exact WKB analysis: We study the quasi-normal modes (QNMs) of a massless scalar perturbation to the extremal M5-branes metric by using the exact WKB analysis. The exact WKB analysis provides two exact QNMs conditions depending on the argument of the co...
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On the Curvature Invariants of the Massive Banados-Teitelboim-Zanelli Black Holes and Their Holographic Pictures: In this paper, the curvature structure of a (2+1)-dimensional black hole in the massive-charged-Born-Infeld gravity is investigated. The metric that we consider is characterized by four degrees of freedom...
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Standard Model Vacua in Heterotic M-Theory: We present a class of N=1 supersymmetric ``standard'' models of particle physics, derived directly from heterotic M-theory, that contain three families of chiral quarks and leptons coupled to the gauge group SU(3)_C X SU(2)_L X U(1)_Y. These models are a fundamental form of `...
hep-th
Dynamical supersymmetry analysis of conformal invariance for superstrings in type IIB R-R plane-wave: In a previous work (arXiv:0902.3750 [hep-th]) we studied the world-sheet conformal invariance for superstrings in type IIB R-R plane-wave in semi-light-cone gauge. Here we give further justification to the results fo...
hep-th
The Bubble of Nothing under T-duality: The bubble of nothing is a solution to Einstein's equations where a circle shrinks and pinches off smoothly. As such, it is one of the simplest examples of a dynamical cobordism to nothing. We take a first step in studying how this solution transforms under T-duality in bosonic st...
hep-th
Continuous Spin Representations of the Poincaré and Super-Poincaré Groups: We construct Wigner's continuous spin representations of the Poincar\'e algebra for massless particles in higher dimensions. The states are labeled both by the length of a space-like translation vector and the Dynkin indices of the {\it short ...
hep-th
Closed String Tachyon Condensation in Supercritical Strings and RG Flows: We show an explicit relation between an RG flow of a two-dimensional gravity and an on-shell tachyon condensation in the corresponding string theory, in the case when the string theory is supercritical. The shape of the tachyon potential in this ...
hep-th
Kinklike structures in models of the Dirac-Born-Infeld type: The present work investigates several models of a single real scalar field, engendering kinetic term of the Dirac-Born-Infeld type. Such theories introduce nonlinearities to the kinetic part of the Lagrangian, which presents a square root restricting the fiel...
hep-th
Hamiltonian reduction and supersymmetric mechanics with Dirac monopole: We apply the technique of Hamiltonian reduction for the construction of three-dimensional ${\cal N}=4$ supersymmetric mechanics specified by the presence of a Dirac monopole. For this purpose we take the conventional ${\cal N}=4$ supersymmetric mec...
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A Mini-Landscape of Exact MSSM Spectra in Heterotic Orbifolds: We explore a ``fertile patch'' of the heterotic landscape based on a Z_6-II orbifold with SO(10) and E_6 local GUT structures. We search for models allowing for the exact MSSM spectrum. Our result is that of order 100 out of a total 3\times 10^4 inequivalen...
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Quantum group gauge theory on quantum spaces: We construct quantum group-valued canonical connections on quantum homogeneous spaces, including a q-deformed Dirac monopole on the quantum sphere of Podles quantum differential coming from the 3-D calculus of Woronowicz on $SU_q(2)$ . The construction is presented within t...
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Lagrange Brackets and U(1) fields: The idea of a companion Lagrangian associated with $p$-Branes is extended to include the presence of U(1) fields. The Brane Lagrangians are constructed with $F_{ij}$ represented in terms of Lagrange Brackets, which make manifest the reparametrisation invariance of the theory; these ar...
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Quantum Einstein Gravity as a Topological Field Theory: General covariance in quantum gravity is seen once one integrates over all possible metrics. In recent years topological field theories have given us a different route to general covariance without integrating over all possible metrics. Here we argue that Einstein...
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Critical exponents of the Gross-Neveu model from the effective average action: The phase transition of the Gross-Neveu model with N fermions is investigated by means of a non-perturbative evolution equation for the scale dependence of the effective average action. The critical exponents and scaling amplitudes are cal...
hep-th
Super Gluon Five-Point Amplitudes in AdS Space: We present the tree-level five-point amplitude of the lowest KK mode of SYM on AdS$_5$$\times$S$^3$, dual to the correlator of the flavor current multiplet in the dual 4d ${\cal N}=2$ SCFT. Its color and kinematical structure is particularly simple and resembles that of t...
hep-th
Comparing Double String Theory Actions: Aimed to a deeper comprehension of a manifestly T-dual invariant formulation of string theory, in this paper a detailed comparison between the non-covariant action proposed by Tseytlin and the covariant one proposed by Hull is done. These are obtained by making both the string co...
hep-th
Superpotential de-sequestering in string models: Non-perturbative superpotential cross-couplings between visible sector matter and K\"ahler moduli can lead to significant flavour-changing neutral currents in compactifications of type IIB string theory. Here, we compute corrections to Yukawa couplings in orbifold models...
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On General BCJ Relation at One-loop Level in Yang-Mills Theory: BCJ relation reveals a dual between color structures and kinematic structure and can be used to reduce the number of independent color-ordered amplitudes at tree level. Refer to the loop-level in Yang-Mills theory, we investigate the similar BCJ relation i...
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Non-Abelian Confinement in N=2 Supersymmetric QCD: Duality and Kinks on Confining Strings: Recently we observed a crossover transition (in the Fayet-Iliopoulos parameter) from weak to strong coupling in N=2 supersymmetric QCD with the U(N) gauge group and N_f > N quark flavors. At strong coupling this theory can be d...
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String theory and the 4D/3D reduction of Seiberg duality. A Review: We review the reduction of four-dimensional N=1 Seiberg duality to three dimensions focusing on the D brane engineering approach. We start with an overview of four-dimensional Seiberg duality for theories with various types of gauge groups and matter c...
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Combinatorial $B_n$-analogues of Schubert polynomials: Combinatorial $B_n$-analogues of Schubert polynomials and corresponding symmetric functions are constructed from an exponential solution of the $B_n$-Yang-Baxter equation that involves the nilCoxeter algebra of the hyperoctahedral group.
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Singularity-free model of electric charge in physical vacuum: Non-zero spatial extent and mass generation: We propose a model of a spinless electrical charge as a self-consistent field configuration of the electromagnetic (EM) field interacting with a physical vacuum effectively described by the logarithmic quantum B...
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Entanglement Entropy at Finite Density from Extremal Black Holes: I compute the entanglement entropy of a strongly coupled 2+1d quantum field theory containing fermions at finite density using gauge/gravity duality. The dual geometry is an extremal black hole in 3+1d Einstein-Maxwell theory. This system was recently sh...
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Forces from Connes' geometry: We try to give a pedagogical introduction to Connes' derivation of the standard model of electro-magnetic, weak and strong forces from gravity.
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Quantum Null Energy Condition and its (non)saturation in 2d CFTs: We consider the Quantum Null Energy Condition (QNEC) for holographic conformal field theories in two spacetime dimensions (CFT$_2$). We show that QNEC saturates for all states dual to vacuum solutions of AdS$_3$ Einstein gravity, including systems that a...
hep-th
Einstein gravity from the ${\N=4}$ spinning particle: We obtain a manifestly background independent BRST quantization of the $\N=4$ supersymmetric spinning particle. We show that nilpotency of the BRST charge $Q$ implies the Einstein equations admitting a cosmological constant of indefinite sign. The physical graviton ...
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Natural inflation with multiple sub-Planckian axions: We extend the Kim-Nilles-Peloso (KNP) alignment mechanism for natural inflation to models with $N>2$ axions, which obtains a super-Planckian effective axion decay constant $f_{\textrm{eff}}\gg M_{Pl}$ through an alignment of the anomaly coefficients of multiple axio...
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Closed Universe in Mirage Cosmology: We study the cosmological evolution of the closed universe on a spherical probe brane moving in the AdS$_m\times S^n$ background and the near-horizon background of the dilatonic D-branes. The Friedmann equations describing the evolution of the brane universe, and the effective energ...
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Lattice Super Yang-Mills: A Virial Approach to Operator Dimensions: The task of calculating operator dimensions in the planar limit of N=4 super Yang-Mills theory can be vastly simplified by mapping the dilatation generator to the Hamiltonian of an integrable spin chain. The Bethe ansatz has been used in this context t...
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The $L_{\infty}$ structure of gauge theories with matter: In this work we present an algebraic approach to the dynamics and perturbation theory at tree-level for gauge theories coupled to matter. The field theories we will consider are: Chern-Simons-Matter, Quantum Chromodynamics, and scalar Quantum Chromodynamics. Sta...
hep-th
Quenched mesonic spectrum at large N: We compute the masses of the $\pi$ and of the $\rho$ mesons in the quenched approximation on a lattice with fixed lattice spacing $a \simeq 0.145 \ \mathrm{fm}$ for SU($N$) gauge theory with $N = 2,3,4,6$. We find that a simple linear expression in $1/N^2$ correctly captures the fe...
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Hamiltonian formalism for Bose excitations in a plasma with a non-Abelian interaction I: plasmon -- hard particle scattering: The Hamiltonian theory for the collective longitudinally polarized gluon excitations (plasmons) coupling with classical high-energy test color-charged particle propagating through a high-tempe...
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Comment on ``On spin-1 massive particles coupled to a Chern-Simons field'': In this comment we discuss some serious inconsistencies presented by Gomes, Malacarne and da Silva in their paper, Phys.Rev. D60 (1999) 125016 (hep-th/9908181).
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The Monodromic Axion-Photon Coupling: We consider the general form of the axion coupling to photons in the axion-Maxwell theory. On general grounds this coupling takes the form of a monodromic function of the axion, which we call $g(a)$, multiplying the Chern-Pontryagin density $F \widetilde{F}$ of the photon. We show ...
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Application of the canonical quantization of systems with curved phase space to the EMDA theory: The canonical quantization of dynamical systems with curved phase space introduced by I.A. Batalin, E.S. Fradkin and T.E. Fradkina is applied to the four-dimensional Einstein-Maxwell Dilaton-Axion theory. The spherically ...
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Generalized Uncertainty Principle: Implications for Black Hole Complementarity: At the heart of the black hole information loss paradox and the firewall controversy lies the conflict between quantum mechanics and general relativity. Much has been said about quantum corrections to general relativity, but much less in ...
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The Number Operator for Generalized Quons: We construct the number operator for particles obeying infinite statistics, defined by a generalized q-deformation of the Heisenberg algebra, and prove the positivity of the norm of linearly independent state vectors.
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Curiosities above c = 24: Two-dimensional rational CFT are characterised by an integer $\ell$, related to the number of zeroes of the Wronskian of the characters. For two-character RCFT's with $\ell<6$ there is a finite number of theories and most of these are classified. Recently it has been shown that for $\ell \ge 6...
hep-th
Coupled Inflation and Brane Gases: We study an effective four-dimensional theory with an action with two scalar fields minimally coupled to gravity, and with a matter action which couples to the two scalar fields via an overall field-dependent coefficient in the action. Such a theory could arise from a dimensional redu...
hep-th
Remarks on a $B \wedge F$ model with topological mass from gauging spin: Aspects of screening and confinement are reassessed for a $B \wedge F$ model with topological mass with the gauging of spin. Our discussion is carried out using the gauge-invariant, but path-dependent, variables formalism. We explicitly show that ...
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Practicalities of renormalizing quantum field theories: We review the techniques used to renormalize quantum field theories at several loop orders. This includes the techniques to systematically extract the infinities in a Feynman integral and the implementation of the algorithm within computer algebra. To illustrate t...
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On the Two-Point Correlation Function in Dynamical Scaling and SCHRÖdinger Invariance: The extension of dynamical scaling to local, space-time dependent rescaling factors is investigated. For a dynamical exponent $z=2$, the corresponding invariance group is the Schr\"odinger group. Schr\"odinger invariance is shown t...
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The large Nc limit of N=2 super Yang-Mills, fractional instantons and infrared divergences: We investigate the large Nc limit of pure N=2 supersymmetric gauge theory with gauge group SU(Nc) by using the exact low energy effective action. Typical one-complex dimensional sections of the moduli space parametrized by a g...
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Mobility edge and Black Hole Horizon: We conjecture that the mobility edge in the 4D Euclidean Dirac operator spectrum in QCD in the deconfined phase found in the lattice studies corresponds to the near black hole (BH) horizon region in the holographic dual. We present some evidences both from the field theory side and...
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Universal Bounds in Even-Spin CFTs: We prove using invariance under the modular $S$- and $ST$-transformations that every unitary two-dimensional conformal field theory (CFT) of only even-spin operators (with no extended chiral algebra and with central charges $c,\tilde{c}>1$) contains a primary operator with dimension ...
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Thermal Operator Representation of Finite Temperature Graphs II: Using the mixed space representation, we extend our earlier analysis to the case of Dirac and gauge fields and show that in the absence of a chemical potential, the finite temperature Feynman diagrams can be related to the corresponding zero temperature g...
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Tachyonic Instability and Darboux Transformation: Using Darboux transformation one can construct infinite family of potentials which lead to the flat spectrum of scalar field fluctuations with arbitrary multiple precision, and, at the same time, with "essentially blue" spectrum of perturbations of metric. Besides, we d...
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Fusion Algebras Induced by Representations of the Modular Group: Using the representation theory of the subgroups SL_2(Z_p) of the modular group we investigate the induced fusion algebras in some simple examples. Only some of these representations lead to 'good' fusion algebras. Furthermore, the conformal dimensions an...
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BPS Supermultiplets in Five Dimensions: BPS representations of 5-dimensional supersymmetry algebras are classified. For BPS states preserving 1/2 the supersymmetry, there are two distinct classes of multiplets for N=4 supersymmetry and three classes for N=8 supersymmetry. For N=4 matter theories, the two 1/2 supersymme...
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Quantization and the Issue of Time for Various Two-Dimensional Models of Gravity: It is shown that the models of 2D Liouville Gravity, 2D Black Hole- and $R^2$-Gravity are {\em embedded} in the Katanaev-Volovich model of 2D NonEinsteinian Gravity. Different approaches to the formulation of a quantum theory for the ...
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Criticality and Transport in Magnetized Holographic Systems: In this master's thesis the Einstein-Maxwell-Dilaton theory is used to model the dynamics of 2+1-dimensional, strongly coupled, large-$N$ quantum field theories with intrinsic T-violation, at finite density and temperature, in the presence of a magnetic field...
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Quantum Black Hole Formation in the BFSS Matrix Model: We study the various head-on collisions of two bunches of D0-branes and their real-time evolution in the BFSS matrix model in classical limit. For a various matrix size N respecting the 't Hooft scaling, we find quantitative evidence for the formation of a single b...
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Metal or Insulator? Dirac operator spectrum in holographic QCD: The lattice studies in QCD demonstrate the nontrivial localization behavior of the eigenmodes of the 4D Euclidean Dirac operator considered as Hamiltonian of $4+1$ dimensional disordered system. We use the holographic viewpoint to provide the conjectural e...
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Gauss-Bonnet black holes supported by a nonlinear electromagnetic field: We study $D$-dimensional charged static spherically symmetric black hole solutions in Gauss-Bonnet theory coupled to nonlinear electrodynamics defined as arbitrary functions of the field invariant and constrained by several physical conditions. Th...
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Microscopics of Extremal Kerr from Spinning M5 Branes: We show that the spinning magnetic one-brane in minimal five-dimensional supergravity admits a decoupling limit that interpolates smoothly between a self-dual null orbifold of AdS_3 \times S^2 and the near-horizon limit of the extremal Kerr black hole times a circl...
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Why Comparable? A Multiverse Explanation of the Dark Matter-Baryon Coincidence: The densities of dark and baryonic matter are comparable: \zeta = \rho_D / \rho_B ~ O(1). This is surprising because they are controlled by different combinations of low-energy physics parameters. Here we consider the probability distribu...
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DBI Galileon inflation in background SUGRA: We introduce a model of potential driven DBI Galileon inflation in background N=1,D=4 SUGRA. Starting from D4-$\bar{D4}$ brane-antibrane in the bulk N=2,D=5 SUGRA including quadratic Gauss-Bonnet corrections, we derive an effective N=1,D=4 SUGRA by dimensional reduction, that...
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PT symmetric fermionic field theories with axions: Renormalization and dynamical mass generation: We consider the renormalisation properties of non-Hermitian Yukawa theories involving a pseudoscalar (axion) field at or near $4$ dimensions. The non-Hermiticity is \cPT-symmetric where $\mathcal P$ is a linear idempoten...
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Clarifying perturbations in the ekpyrotic universe: In this note I try to clarify the problem of perturbations in the ekpyrotic universe. I write down the most general matching conditions and specify the choices taken by the two debating sides. I also bring up the problem of surface stresses which always have to be pre...
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Dualities in the classical supergravity limits: Duality symmetries of supergravity theories are powerful tools to restrict the number of possible actions, to link different dimensions and number of supersymmetries and might help to control quantisation. (Hodge-Dirac-)Dualisation of gauge potentials exchanges Noether an...
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Thick Domain Walls and Charged Dilaton Black Holes: We study a black hole domain wall system in dilaton gravity which is the low-energy limit of the superstring theory. We solve numerically equations of motion for real self-interacting scalar field and justify the existence of static axisymmetric field configuration re...
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Supergravity p-branes revisited: extra parameters, uniqueness, and topological censorship: We perform a complete integration of the Einstein-dilaton-antisymmetric form action describing black p-branes in arbitrary dimensions assuming the transverse space to be homogeneous and possessing spherical, toroidal or hyperbo...
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An Alternative to Compactification: Conventional wisdom states that Newton's force law implies only four non-compact dimensions. We demonstrate that this is not necessarily true in the presence of a non-factorizable background geometry. The specific example we study is a single 3-brane embedded in five dimensions. We s...
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Born-Infeld Black-Body Radiation: The problem of black-body radiation is considered in the Born-Infeld theory of electrodynamics. In particular, at 2-loop order the deviation from the Planck expression due to the self-interaction of photons is calculated. It is seen that the system of interacting photons of the theory,...
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Gravitational lensing and shadow of charged black holes in the low-energy limit of string theory: In this work, we investigate the shadow cast and strong field gravitational lensing of a new class of black hole solutions in dilaton gravity where dilaton field is coupled with nonlinear Maxwell invariant [Younesizadeh ...
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Scaling Behaviors of Branched Polymers: We study the thermodynamic behavior of branched polymers. We first study random walks in order to clarify the thermodynamic relation between the canonical ensemble and the grand canonical ensemble. We then show that correlation functions for branched polymers are given by those f...
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T-Duality Group for Open String Theory: We study T-duality for open strings on tori $\T^d$. The general boundary conditions for the open strings are constructed, and it is shown that T-duality group, which preserves the mass spectrum of closed strings, preserves also the mass spectrum of the open strings. The open stri...
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