Shear viscosity, instability and the upper bound of the Gauss-Bonnet coupling constant

TL;DR

This paper analyzes how the shear viscosity to entropy ratio in charged black branes with Gauss-Bonnet correction depends on dimensionality, establishing bounds on the coupling constant to ensure causality and stability, especially in high dimensions.

Contribution

It provides a detailed calculation of the dimensionality dependence of η/s with Gauss-Bonnet correction and derives bounds on the coupling constant based on causality and stability constraints.

Findings

Gauss-Bonnet coupling constant bounded by 1/4 in infinite dimensions

Higher dimensions stabilize gravitational perturbations

Stability linked to coupling constant bounds

Abstract

We compute the dimensionality dependence of $\eta/s$ for charged black branes with Gauss-Bonnet correction. We find that both causality and stability constrain the value of Gauss-Bonnet coupling constant to be bounded by 1/4 in the infinite dimensionality limit. We further show that higher dimensionality stabilize the gravitational perturbation. The stabilization of the perturbation in higher dimensional space-time is a straightforward consequence of the Gauss-Bonnet coupling constant bound.