118516615
Emergence of supersymmetry on the surface of three-dimensional topological insulators
We propose two possible experimental realizations of a (2 + 1)-dimensional spacetime supersymmetry at a quantum critical point on the surface of three-dimensional topological insulators. The quantum critical point between the semi-metallic state with one Dirac fermion and the s-wave superconducting state on the surface is described by a supersymmetric conformal field theory within the ϵ-expansion. We predict the exact voltage dependence of the differential conductance at the supersymmetric critical point.
118620419
Background independent holographic description: from matrix field theory to quantum gravity
A bstractWe propose a local renormalization group procedure where length scale is changed in spacetime dependent way. Combining this scheme with an earlier observation that high energy modes in renormalization group play the role of dynamical sources for low energy modes at each scale, we provide a prescription to derive background independent holographic duals for field theories. From a first principle construction, it is shown that the holographic theory dual to a D-dimensional matrix field theory is a (D + 1)-dimensional quantum theory of gravity coupled with matter fields of various spins. The gravitational theory has (D + 1) first-class constraints which generate local spacetime transformations in the bulk. The (D + 1)-dimensional diffeomorphism invariance is a consequence of the freedom to choose different local RG schemes.
118451455
Non-Fermi liquid from a charged black hole: A critical Fermi ball
Using the anti-de Sitter/conformal field theory correspondence, we calculate a fermionic spectral function in a 2+1 dimensional nonrelativistic quantum field theory which is dual to a gravitational theory in the AdS{sub 4} background with a charged black hole. The spectral function shows no quasiparticle peak but the Fermi surface is still well-defined. Interestingly, all momentum points inside the Fermi surface are critical and the gapless modes are defined in a critical Fermi ball in the momentum space.
119519436
A dual gravity study of the (2+1)D compact U(1) gauge theory coupled with strongly interacting matter fields
Abstract We consider the D2-brane probe action in the gravity background dual to N coincident D p -branes by treating the separation between the D2- and D p -branes as a non-dynamical parameter for p = 2 , 4 , 6 . The gauge coupling, the core size of a non-BPS instanton and the mass gap of the compact U ( 1 ) gauge theory in the D2-brane are determined as a function of the separation in the type IIA gravity region. The results are interpreted in terms of the ( 2 + 1 ) D U ( 1 ) gauge theory coupled with the matter fields which are also strongly coupled with the ( p + 1 ) D SU ( N ) gauge field. It is shown that strong coupling of the matter fields to the SU ( N ) gauge field can drastically modify their screening of the U ( 1 ) gauge field. The non-perturbative dependence of the U ( 1 ) gauge coupling on the energy scale is obtained.
4971151
Quantum renormalization group and holography
A bstractQuantum renormalization group scheme provides a microscopic understanding of holography through a general mapping between the beta functions of underlying quantum field theories and the holographic actions in the bulk. We show that the Einstein gravity emerges as a holographic description upto two derivative order for a matrix field theory which has no other operator with finite scaling dimension except for the energymomentum tensor. We also point out that holographic actions for general large N matrix field theories respect the inversion symmetry along the radial direction in the bulk if the beta functions of single-trace operators are gradient flows with respect to the target space metric set by the beta functions of double-trace operators.
119254533
Holographic Matter: Deconfined String at Criticality
We derive a holographic dual for a gauged matrix model in general dimensions from a first-principle construction. The dual theory is shown to be a field theory of closed loops which includes a compact two-form gauge field coupled with closed loops in one higher-dimensional space. Small fluctuations of the loop fields around a saddle point are identified as propagating strings. Possible phases of the matrix model are discussed in the holographic description. Besides the confinement phase and the IR free deconfinement phase, there can be two different classes of critical states. The first class describes holographic critical states where strings are deconfined in the bulk. The second class describes non-holographic critical states where strings are confined due to proliferation of topological defects for the two-form gauge field. This implies that the critical states of the matrix model which admit holographic descriptions with deconfined string in the bulk form novel universality classes with non-trivial quantum orders which make the holographic critical states qualitatively distinct from the non-holographic critical states. The signatures of the non-trivial quantum orders in the holographic states are discussed. Finally, we discuss a possibility that open strings emerge as fractionalized excitations of closed strings along with an emergent one-form gauge field in the bulk.
17587151
Nuclear Density-Dependent Effective Coupling Constants in the Mean-Field Theory
It is shown that the equation of state of nuclear matter can be determined within the mean-field theory of $\sigma \omega$ model provided only that the nucleon effective mass curve is given. We use a family of the possible nucleon effective mass curves that reproduce the empirical saturation point in the calculation of the nuclear binding energy curves in order to obtain density-dependent effective coupling constants. The resulting density-dependent coupling constants may be used to study a possible equation of state of nuclear system at high density or neutron matter. Within the constraints used in this paper to $M^*$ of nuclear matter at saturation point and zero density, neutron matter of large incompressibility is strongly bound at high density while soft neutron matter is weakly bound at low density. The study also exhibits the importance of surface vibration modes in the study of nuclear equation of state.
12450781
Topological Chern-Simons sigma model
We consider topological twisting of recently constructed Chern-Simons-matter theories in three dimensions with = 4 or higher supersymmetry. We enumerate physically inequivalent twistings for each , and find two different twistings for = 4, one for = 5,6, and four for = 8. We construct the two types of = 4 topological theories, which we call A/B-models, in full detail. The A-model has been recently studied by Kapustin and Saulina. The B-model is new and it consists solely of a Chern-Simons term of a complex gauge field up to BRST-exact terms. We also compare the new theories with topological Yang-Mills theories and find some interesting connections. In particular, the A-model seems to offer a new perspective on Casson invariant and its relation to Rozansky-Witten theory.
118377735
Free energy versus internal energy potential for heavy quark systems at finite temperature
Using the QCD sum rule with its operator product expansion reliably determined from lattice calculations for the pressure and energy density of hot QCD matter, we calculate the strength of the $J/\ensuremath{\psi}$ wave function at the origin and find that it decreases with temperature when the temperature is in the vicinity of the transition temperature. This result is shown to follow exactly that obtained from the solution of the Schr\"odinger equation for a charm and anticharm quark pair with a temperature independent quark mass using the free energy from lattice calculations as the potential and is in sharp contrast to that using the deeper potential associated with the internal energy, which shows an enhanced strength of the $J/\ensuremath{\psi}$ wave function at the origin. Our result thus suggests that the free energy potential from lattice calculations is the appropriate heavy-quark potential for analyzing the charmonium spectrum at a finite temperature.
120385865
Is the momentum space optimally used with the FODO lattices
The available momentum space of a FODO lattice is determined by the maximum value of the dispersion function (δx=Dx ∂p/p). In a regular FODO lattice the dispersion function oscillates between its maximum and minimum values, which are always positive. The maximum value of the dispersion function in a FODO cell of a fixed length depends on the cell phase difference. An example of a new lattice, in which the dispersion function is lowered to half its value in the same FODO cell, is presented. The available momentum space in the new lattice is raised to twice that in the FODO lattice by allowing the dispersion function to oscillate between the same positive and negative values. The maxima of the dispersion function in the new lattice have half the value of those within the regular 90° cells.
17171580
Emergence of classicality in quantum phase transitions
We show that classicality emerges during quantum phase transitions due to parametric interactions without coupling to environments. The Wigner functions are explicitly calculated for the Gaussian vacuum, number, and thermal states of a free scalar field that describes the spinodal instability regime. The Wigner functions are sharply peaked around their classical trajectories during the phase transition and exhibit classical correlation only for unstable long wavelength modes but retain quantum coherence for short wavelength modes. Thus classicality emerges from the quantum evolution of phase transitions without a classical order parameter. We define a quantal ordering parameter that is linear in the field variable and satisfies the classical field equation.