We consider the AdS 4 RN black hole and work out the momentum dependent hydrodynamic analysis for the vector modes. We also perform the spectral function calculation of the dual field theory. As an application, we consider the permittivity and permeability and find that for low frequency regime, the index of refraction is found to be negative, supporting the claim made in ref.[20] for AdS 5 . We also find that at static limit the medium has the zero permeability, a character of the superconductivity .

A holographic dual of hadrons at finite density is considered. We use the zero blackhole mass limit of Reisner-Nordstrom (RN) AdS background with hard wall to describe a confining background with finite quark density. We calculate density-dependence of meson masses and decay constants. In our model, pion decay constant and its velocity go down but all the meson masses go up as density grows.

Abstract:We calculate the thermal spectral function of SYM plasma with finite density using holographic technique. The gravity dual of the finite temperature and density is taken as the RN-AdS black hole. In the presence of charge, linearized vector modes of gravitational and electromagnetic perturbation are coupled with each other. By introducing master variables for these modes, we solve the coupled system and calculate spectral function. We also calculate photo-emission rate of our gauge theory plasma from spectral function for light like momentum. AC, dc conductivity and their density dependence is also computed.

We calculate the vector isospin susceptibility in AdS/QCD models to study QCD phase transition. In the hard wall model, we show explicitly that the infalling boundary condition at the horizon can be treated as a Dirichlet boundary with a fine-tuned boundary value in the zero frequency and momentum limit. With the infalling boundary condition, we uniquely determine the overall normalization of the vector isospin susceptibility in the hard wall model. In the framework of the soft wall model, we obtain the vector isospin susceptibility with and without Hawking-Page transition and compare our results with lattice QCD. We briefly discuss the chiral symmetry restoration in the AdS/QCD models.

We revisit holographic mesons in the D4/D6 model to study holographic light vector mesons and the properties of heavy quarkonium in confining and deconfining phases. To treat the light mesons and heavy quarkonium on the same footing, we use the same compactification scale M KK in both systems. We observe that like scalar and pseudo-scalar mesons the vector meson mass is linearly proportional to the square root of the quark mass, when the quark mass is large. With a M KK fixed by light meson masses, we calculate the mass of heavy quarkonium in confining and deconfining phases. We also obtain the inmedium dispersion relation for heavy quarkonium, which is important to understand the dissociation and the screening mass of heavy quarkonium in quark-gluon plasma.