Holographic vector mesons from spectral functions at finite baryon or isospin density

Abstract

We consider gauge/gravity duality with flavor for the finite-temperature field theory dual of the AdSSchwarzschild black hole background with embedded D7-brane probes. In particular, we investigate spectral functions at finite baryon density in the black hole phase. We determine the resonance frequencies corresponding to meson-mass peaks as function of the quark mass over temperature ratio. We find that these frequencies have a minimum for a finite value of the quark mass. If the quotient of quark mass and temperature is increased further, the peaks move to larger frequencies. At the same time the peaks narrow, in agreement with the formation of nearly stable vector meson states which exactly reproduce the mesonmass spectrum found at zero temperature. We also calculate the diffusion coefficient, which has finite value for all quark mass to temperature ratios, and exhibits a first-order phase transition. Finally we consider an isospin chemical potential and find that the spectral functions display a resonance peak splitting, similar to the isospin meson-mass splitting observed in effective QCD models.

Mesons in gauge/gravity duals

“…In particular, there are unstable regions in the phase diagrams. Studies of finite chemical potential and finite density effects for D7 brane probes in the AdS-Schwarzschild background may be found in [101,[202][203][204][205][206][207][208][209][210].…”

Photoemission rate of strongly interacting quark-gluon plasma at finite density

“…The spectral function with and without baryon density in the probe brane approach was already calculated [16,17,18,19,21,22,23]. However in that approach the gravity back reaction to the presence of the charge is neglected.…”

Holographic hadrons in a confining finite density medium

“…The holographic encoding of the baryon chemical potential was studied in [5,6,7]. The equations of state were analyzed in [6] and the spectral functions were calculated in [8]. While the prescription for encoding finite temperature has been clear from the early days of AdS/CFT, it is still not clear in all contexts about the geometry describing finite baryon density.…”