D3-D7 Quark-Gluon Plasmas at Finite Baryon Density

TL;DR

This paper constructs a string theory dual for a strongly coupled plasma with fundamental flavors at finite temperature and baryon density, analyzing thermodynamics, energy loss, and optical properties.

Contribution

It provides an analytical solution for the D3-D7 system at finite baryon density, extending holographic models to include backreaction of flavors and baryon density effects.

Findings

Analytical solutions valid at small parameters

Detailed thermodynamic analysis in different ensembles

Quantitative study of jet quenching dependence on baryon density

Abstract

We present the string dual to SU(Nc) N=4 SYM, coupled to Nf massless fundamental flavors, at finite temperature and baryon density. The solution is determined by two dimensionless parameters, both depending on the 't Hooft coupling $\lambda_h$ at the scale set by the temperature T: $\epsilon_h\sim\lambda_h Nf/Nc$, weighting the backreaction of the flavor fields and $\tilde\delta\sim\lambda_h^{-1/2}nb/(Nf T^3)$, where $nb$ is the baryon density. For small values of these two parameters the solution is given analytically up to second order. We study the thermodynamics of the system in the canonical and grand-canonical ensembles. We then analyze the energy loss of partons moving through the plasma, computing the jet quenching parameter and studying its dependence on the baryon density. Finally, we analyze certain "optical" properties of the plasma. The whole setup is generalized to non abelian strongly coupled plasmas engineered on D3-D7 systems with D3-branes placed at the tip of a generic singular Calabi-Yau cone. In all the cases, fundamental matter fields are introduced by means of homogeneously smeared D7-branes and the flavor symmetry group is thus a product of abelian factors.