Higher Curvature Gravity and the Holographic fluid dual to flat spacetime

TL;DR

This paper explores how higher curvature modifications to Einstein gravity influence the holographic dual fluid's properties in flat spacetime, confirming the universality of shear viscosity to entropy density ratio and analyzing second order transport coefficients.

Contribution

It demonstrates that the shear viscosity to entropy density ratio remains universal in higher curvature gravity duals in flat spacetime and computes second order transport coefficients in Einstein-Gauss-Bonnet gravity.

Findings

Shear viscosity to entropy density ratio remains 1/4π in higher curvature theories.

Second order transport coefficients depend on gravitational dynamics.

Results are explicitly calculated for five-dimensional Einstein-Gauss-Bonnet gravity.

Abstract

Recent works have demonstrated that one can construct a (d+2) dimensional solution of the vacuum Einstein equations that is dual to a (d+1) dimensional fluid satisfying the incompressible Navier-Stokes equations. In one important example, the fluid lives on a fixed timelike surface in the flat Rindler spacetime associated with an accelerated observer. In this paper, we show that the shear viscosity to entropy density ratio of the fluid takes the universal value 1/4\pi in a wide class of higher curvature generalizations to Einstein gravity. Unlike the fluid dual to asymptotically anti-de Sitter spacetimes, here the choice of gravitational dynamics only affects the second order transport coefficients. We explicitly calculate these in five-dimensional Einstein-Gauss-Bonnet gravity and discuss the implications of our results.