Viscous hydrodynamics relaxation time from AdS/CFT

TL;DR

This paper uses AdS/CFT correspondence to analyze the relaxation time of a strongly coupled plasma, finding it significantly shorter than weak coupling predictions and revealing the necessity of dilaton activation for nonsingular dual geometries.

Contribution

It provides a novel calculation of the relaxation time in strongly coupled plasma using holography, highlighting differences from weak coupling estimates and implications for dual geometry regularity.

Findings

Relaxation time is about thirty times shorter than weak coupling estimates.

Nonsingularity of the dual geometry requires activating the dilaton field.

Dilaton expectation value scales as tau^(-10/3).

Abstract

We consider an expanding boost-invariant plasma at strong coupling using the AdS/CFT correspondence for N=4 SYM. We determine the relaxation time in second order viscous hydrodynamics and find that it is around thirty times shorter than weak coupling expectations. We find that the nonsingularity of the dual geometry in the string frame necessitates turning on the dilaton which leads to a nonvanishing expectation value for tr F^2 behaving like tau^(-10/3).