Hydrodynamics of fundamental matter

TL;DR

This paper calculates second-order transport coefficients for a strongly coupled plasma with fundamental matter using holography, revealing universal behaviors and bounds related to conformality breaking effects.

Contribution

It provides the first next-to-leading order holographic calculation of transport coefficients in a fundamental-matter plasma and proposes universality conjectures for non-conformal plasmas.

Findings

Bulk viscosity saturates Buchel's bound.

Effective holographic dual captures key transport properties.

Proposes universality of certain hydrodynamic relations for non-conformal plasmas.

Abstract

First and second order transport coefficients are calculated for the strongly coupled N=4 SYM plasma coupled to massless fundamental matter in the Veneziano limit. The results, including among others the value of the bulk viscosity and some relaxation times, are presented at next-to-leading order in the flavor contribution. The bulk viscosity is found to saturate Buchel's bound. This result is also captured by an effective single-scalar five-dimensional holographic dual in the Chamblin-Reall class and it is suggested to hold, in the limit of small deformations, for generic plasmas with gravity duals, whenever the leading conformality breaking effects are driven by marginally (ir)relevant operators. This proposal is then extended to other relations for hydrodynamic coefficients, which are conjectured to be universal for every non-conformal plasma with a dual Chamblin-Reall-like description. Our analysis extends to any strongly coupled gauge theory describing the low energy dynamics of Nc>>1 D3-branes at the tip of a generic Calabi-Yau cone. The fundamental fields are added by means of 1<<Nf<<Nc homogeneously smeared D7-branes.