Shear viscosity and instability from third order Lovelock gravity

TL;DR

This paper computes the shear viscosity to entropy density ratio for charged black branes in third order Lovelock gravity, finding it consistent with previous predictions and analyzing stability and causality constraints.

Contribution

It provides the first calculation of shear viscosity in third order Lovelock gravity and shows that this term does not cause causality violations unlike Gauss-Bonnet gravity.

Findings

Shear viscosity to entropy density ratio matches previous predictions for chargeless black branes.

Third order Lovelock term does not induce causality violations.

Black brane stability bounds the Lovelock coupling constant to 1/4 in infinite dimensions.

Abstract

We calculate the ratio of shear viscosity to entropy density for charged black branes in third order Lovelock theory. For chargeless black branes, the result turns out to be consistent with the prediction made in $\rm arXiv:0808.3498[\rm hep-th] $. We find that, the third order Lovelock gravity term does not contribute to causality violation unlike the Gauss-Bonnet term. The stability of the black brane again requires the value of the Lovelock coupling constant to be bounded by 1/4 in the infinite dimensionality limit.