Density Dependence of Transport Coefficients from Holographic Hydrodynamics

TL;DR

This paper investigates how transport coefficients like diffusion, shear viscosity, and thermal conductivity of the Quark-Gluon Plasma depend on density and temperature using holographic models, confirming hydrodynamic relations.

Contribution

It provides a holographic calculation of transport coefficients at finite density and temperature, revealing their density dependence and validating hydrodynamic relations.

Findings

Diffusion constant decreases with density at fixed energy.

Shear viscosity decreases with density at fixed temperature.

Hydrodynamic relations between coefficients are exactly satisfied.

Abstract

We study the transport coefficients of Quark-Gluon-Plasma in finite temperature and finite baryon density. We use AdS/QCD of charged AdS black hole background with bulk-filling branes identifying the U(1) charge as the baryon number. We calculate the diffusion constant, the shear viscosity and the thermal conductivity to plot their density and temperature dependences. Hydrodynamic relations between those are shown to hold exactly. The diffusion constant and the shear viscosity are decreasing as a function of density for fixed total energy. For fixed temperature, the fluid becomes less diffusible and more viscous for larger baryon density.