Shear Viscosity and Chern-Simons Diffusion Rate from Hyperbolic Horizons

TL;DR

This paper computes shear viscosity and baryon number violation rates in quantum field theories with gravity duals, revealing a temperature-dependent ratio of shear viscosity to entropy density that can be arbitrarily small at low temperatures.

Contribution

It provides explicit calculations of shear viscosity and Chern-Simons diffusion rate for theories with hyperbolic horizon gravity duals, highlighting the temperature dependence of these quantities.

Findings

Shear viscosity to entropy density ratio is below 1/(4π) at all temperatures.

The ratio can be made arbitrarily small in the low temperature limit.

Explicit dependence of transport coefficients on temperature is established.

Abstract

We calculate the shear viscosity and anomalous baryon number violation rate in quantum field theories at finite temperature having gravity duals with hyperbolic horizons. We find the explicit dependence of these quantities on the temperature. We show that the ratio of shear viscosity to entropy density is below $1/(4\pi)$ at all temperatures and it can be made arbitrarily small in the low temperature limit.