Thermoelectric transport in holographic quantum matter under shear strain

We study thermoelectric transport under shear strain in two spatial dimensional quantum matter using the holographic duality.General analytic formulae for the DC thermoelectric conductivities subjected to finite shear strain are obtained in terms of black hole horizon data.Off-diagonal terms in the conductivity matrix also appear at zero magnetic field,resembling an emergent electronic nematicity,which cannot nevertheless be identified with the presence of an anomalous Hall effect.For an explicit model study,we numerically construct a family of strained black holes and obtain the corresponding nonlinear stress-strain curves.We then compute all electric,thermoelectric,and thermal conductivities and discuss the effects of strain.While the shear elastic deformation does not affect the temperature dependence of thermoelectric and thermal conductivities quantitatively,it can strongly change the behavior of the electric conductivity.For both shear hardening and softening cases,we find a clear metal-insulator transition driven by the shear deformation.Moreover,the violation of the previously conjectured thermal conductivity bound is observed for large shear deformation.

Hadron spectra and pion form factor in dynamical holographic QCD model with anomalous 5D mass of scalar field

The simplest version of the dynamical holographic QCD model is described by adding the KKSS model action on a dilaton-graviton coupled background,in which the AdS5 metric is deformed by the gluon condensation and further deformed by the chiral condensation.In this framework,both the chiral symmetry breaking and linear confinement can be realized.The light-flavor hadron spectra and the pion form factor were investigated,but it was difficult to reconcile the light-flavor hadron spectra and pion form factor.By considering the anomalous 5-dimension mass correction of the scalar field from QCD running coupling,it is found that the light flavor hadron spectra and pion form factor can be described well simultaneously.In particular,the ground state and lower excitation states of the scalar,pseudo scalar,and axial vector meson spectra are improved.However,the vector meson spectra are not sensitive to the anomalous 5-dimension mass correction of the scalar field.

Drag force on heavy quarks from holographic QCD

We study the drag force of a relativistic heavy quark using a holographic QCD model with conformal invariance broken by a background dilaton.The effects of the chemical potential and the confining scale on this quantity are analyzed.The drag force in this model is shown to be larger than that of N=4 supersymmetric Yang-Mills(SYM) plasma.In particular,the inclusion of the chemical potential and confining scale both enhance the drag force,in agreement with earlier findings.Moreover,we discuss how the chemical potential and confining scale influence the diffusion coefficient.

A holographic description of theta-dependent Yang-Mills theory at finite temperature

Theta-dependent gauge theories can be studied using holographic duality through string theory in certain spacetimes.By this correspondence we consider a stack of N_0 dynamical DO-branes as D-instantons in the background sourced by N_c coincident non-extreme black D4-branes.According to the gauge-gravity duality,this D0-D4 brane system corresponds to Yang-Mills theory with a theta angle at finite temperature.We solve the IIA supergravity action by taking account into a sufficiently small backreaction of the Dinstantons and obtain an analytical solution for our D0-D4-brane configuration.Subsequently,the dual theory in the large N_c limit can be holographically investigated with the gravity solution.In the dual field theory,we find that the coupling constant exhibits asymptotic freedom,as is expected in QCD.The contribution of the theta-dependence to the free energy gets suppressed at high temperatures,which is basically consistent with the calculation using the Yang-Mills instanton.The topological susceptibility in the large N_c limit vanishes,and this behavior remarkably agrees with the implications from the simulation results at finite temperature.Moreover,we finally find a geometrical interpretation of the theta-dependence in this holographic system.

Quantum bit threads of MERA tensor network in large c limit

The Ryu-Takayanagi(RT)formula plays a large role in the current theory of gauge-gravity duality and emergent geometry phenomena.The recent reinterpretation of this formula in terms of a set of"bit threads"is an interesting effort in understanding holography.In this study,we investigate a quantum generalization of the"bit threads"based on a tensor network,with particular focus on the multi-scale entanglement renormalization ansatz(MERA).We demonstrate that,in the large c limit,isometries of the MERA can be regarded as"sources"(or"sinks")of the information flow,which extensively modifies the original picture of bit threads by introducing a new variableρ:density of the isometries.In this modified picture of information flow,the isometries can be viewed as generators of the flow.The strong subadditivity and related properties of the entanglement entropy are also obtained in this new picture.The large c limit implies that classical gravity can emerge from the information flow.

Holographic Schwinger effect in a soft wall AdS/QCD model

We perform a potential analysis for the holographic Schwinger effect in a deformed AdS5 model with conformal invariance broken by a background dilaton.We evaluated the static potential by analyzing the classical action of a string attached to a rectangular Wilson loop on a probe D3 brane located at an intermediate position in the bulk AdS space.We observed that the inclusion of the chemical potential tends to enhance the production rate,which is opposite to the effect of the confining scale.In addition,we calculated the critical electric field based on the Dirac-Born-Infeld(DBI)action.