Relaxation time of non-conformal plasma

TL;DR

This paper investigates the relaxation time of non-conformal strongly coupled plasma using gauge/gravity duality, revealing divergence near phase transition despite finite bulk viscosity.

Contribution

It provides the first calculation of relaxation time corrections in non-conformal plasma and analyzes its critical behavior near phase transition.

Findings

Relaxation time diverges near the critical temperature as |1 - T_c/T|^(-1/2).

Bulk viscosity remains finite at the critical point.

Leading corrections to conformal relaxation time are computed from relevant deformations.

Abstract

We study effective relaxation time of viscous hydrodynamics of strongly coupled non-conformal gauge theory plasma using gauge theory/string theory correspondence. We compute leading corrections to the conformal plasma relaxation time from the relevant deformations due to dim-2 and dim-3 operators. We discuss in details the relaxation time tau_eff of N=2^* plasma. For a certain choice of masses this theory undergoes a phase transition with divergent specific heat c_V ~ |1-T_c/T|^(-1/2). Although the bulk viscosity remains finite all the way to the critical temperature, we find that tau_eff diverges near the critical point as tau_eff ~ |1-T_c/T|^(-1/2).