Holographic Schwinger effect in spinning black hole backgrounds

We perform a potential analysis for the holographic Schwinger effect in spinning Myers-Perry black holes.We compute the potential between the produced pair by evaluating the classical action of a string attached on a probe D3-brane at an intermediate position in the AdS bulk.We find that increasing the angular momentum reduces the potential barrier,thus enhancing the Schwinger effect,consistent with previous findings obtained via the local Lorentz transformation.In particular,these effects are more visible for the particle pair lying in the transversal plane compared with that along the longitudinal orientation.In addition,we discuss how the Schwinger effect changes with the shear viscosity to entropy density ratio at strong coupling under the influence of angular momentum.

Surface growth approach for bulk reconstruction in the AdS/BCFT correspondence

In this study,we extend the surface growth approach for bulk reconstruction into the Ad S spacetime with a boundary in the Ad S/BCFT correspondence.We show that the geometry in the entanglement wedge with a boundary can be constructed from the direct growth of bulk extremal surfaces layer by layer.Furthermore,we observe that the surface growth configuration in BCFT can be connected with the defect multi scale entanglement renormalization ansatz(MERA)tensor network.Additionally,we investigate the entanglement of purification within the surface growth process,which not only reveals more refined structure of entanglement entropy in the entanglement wedge but also suggests a selection rule for surface growth in the bulk reconstruction.

Genus two correlation functions in CFTs with TT deformation

Since the definition of TT deformation in the curved Riemann surface is obstructive in the literature,we propose a way to do the deformation in the genus two Riemann surfaces by sewing prescription.We construct the correlation functions of conformal field theories(CFTs)on genus two Riemann surfaces with the TT deformation in terms of the perturbative CFT approach.Thanks to sewing construction to form higher genus Riemann surfaces from lower genus ones and conformal symmetry,we systematically obtain the first-order TT correction to the genus two correlation functions in the TT deformed CFTs,e.g.,partition function and one/higher-point correlation functions.

Holographic axion model: A simple gravitational tool for quantum matter

This is a complete and exhaustive review on the so-called holographic axion model—a bottom-up holographic system characterized by the presence of a set of shift symmetric scalar bulk fields whose profiles are taken to be linear in the spatial coordinates.This simple model implements the breaking of translational invariance of the dual field theory by retaining the homogeneity of the background geometry and therefore allowing for controllable and fast computations. The usages of this model are very vast and they are a proof of the spectacular versatility of the framework. In this review, we touch upon all the up-to-date aspects of this model from its connection with massive gravity and effective field theories, to its role in modeling momentum dissipation and elastic properties ending with all the phenomenological features and its hydrodynamic description. In summary, this is a complete guide to one of the most used models in Applied Holography and a must-read for any researcher entering this field.

Power law of shear viscosity in Einstein-Maxwell-Dilaton-Axion model

We construct charged black hole solutions with hyperscaling violation in the infrared（IR） region in Einstein-Maxwell-Dilaton-Axion theory and investigate the temperature behavior of the ratio of holographic shear viscosity to the entropy density. When translational symmetry breaking is relevant in the IR, the power law of the ratio is verified numerically at low temperature T, namely, η/s ～ T^κ, where the values of exponent κ coincide with the analytical results. We also find that the exponent κ is not affected by irrelevant current, but is reduced by the relevant current.

The dynamical holographic QCD method for hadron physics and QCD matter

In this paper we present a short overview on the dynamical holographic QCD(DhQCD)method for hadron physics and QCD matter.The five-dimensional DhQCD model is constructed in the graviton-dilaton-scalar framework with the dilaton background fieldΦand the scalar field X dual to the gluon condensate and the chiral condensate operator thus can represent the gluodynamics(linear confinement)and chiral dynamics(chiral symmetry breaking),respectively.The dilaton background field and the scalar field are a function of the 5th dimension,which plays the role of the energy scale,in this way,the DhQCD model can resemble the renormalization group from ultraviolet(UV)to infrared(IR).By solving the Einstein equation,the metric structure at IR is automatically deformed by the nonperturbative gluon condensation and chiral condensation in the vacuum.We review the results on the hadron spectra including the glueball spectra,the light/heavy meson spectra,as well as on QCD phase transitions,and thermodynamical as well as transport properties in the framework of the DhQCD model.

AdS/Deep-Learning made easy:simple examples

Deep learning has been widely and actively used in various research areas.Recently,in gauge/gravity duality,a new deep learning technique called AdS/DL(Deep Learning)has been proposed.The goal of this paper is to explain the essence of AdS/DL in the simplest possible setups,without resorting to knowledge of gauge/gravity duality.This perspective will be useful for various physics problems:from the emergent spacetime as a neural network to classical mechanics problems.For prototypical examples,we choose simple classical mechanics problems.This method is slightly different from standard deep learning techniques in the sense that we not only have the right final answers but also obtain physical understanding of learning parameters.

Instability of AdS black holes with lattices

Anti-de Sitter(AdS)black holes with lattices are essential for optical conductivity studies in the holographic approach.We investigate the instability of these black holes that can result in the holographic description of charge density waves.In the presence of homogeneous axion fields,we show that the instability of AdS-Reissner-Nordström(AdS-RN)black holes is always suppressed.However,in the presence of Q-lattices,we find that the unstable region becomes the smallest in the vicinity of the critical region for the metal/insulator phase transition.This novel phenomenon is reminiscent of the behavior of the holographic entanglement entropy during quantum phase transitions.

Note on surface growth approach for bulk reconstruction

In this paper,we show using several examples that the bulk geometry of asymptotically AdS3 spacetimes can be effectively reconstructed using an intuitive and visual method called the surface growth scheme.This new approach for bulk reconstruction was originally proposed in a recent paper,along with its explicit realization using the one-shot entanglement distillation tensor network and the surface/state correspondence.In this paper,we directly analyze the growth of the bulk minimal surfaces to implement this scheme.Our study provides further support for the surface growth approach in entanglement wedge reconstruction.

Holographic superconductor on a novel insulator

We construct a holographic superconductor model, based on a gravity theory, which exhibits novel metal-insulator transitions. We investigate the condition for the condensation of the scalar field over the parameter space, and then focus on the superconductivity over the insulating phase with a hard gap, which is supposed to be Mott-like. It turns out that the formation of the hard gap in the insulating phase benefits the superconductivity.This phenomenon is analogous to the fact that the pseudogap phase can promote the pre-pairing of electrons in high Tccuprates. We expect that this work can shed light on understanding the mechanism of high Tcsuperconductivity from the holographic side.