Improved Hydrodynamics from the AdS/CFT

TL;DR

This paper extends relativistic hydrodynamics to include all order gradient terms and uses AdS/CFT duality to compute associated transport coefficients, revealing higher order effects tend to diminish viscosity.

Contribution

It introduces a comprehensive gradient expansion in hydrodynamics and calculates higher order transport coefficients via AdS/CFT for ${\

Findings

Higher order terms reduce the effective viscosity.

Computed third- and fourth-order transport coefficients.

Extended hydrodynamics framework with all gradient orders.

Abstract

We generalize (linearized) relativistic hydrodynamics by including all order gradient expansion of the energy momentum tensor, parametrized by four momenta-dependend transport coefficients, one of which is the usual shear viscosity. We then apply the AdS/CFT duality for ${\cal N}=4$ SUSY in order to compute the retarded correlators of the energy-momentum tensor. From these correlators we determine a large set of transport coefficients of third- and fourth-order hydrodynamics. We find that higher order terms have a tendency to reduce the effect of viscosity.