Viscosity to entropy ratio at extremality

TL;DR

This paper demonstrates that the viscosity to entropy ratio is universally 1/(4 pi) for a broad class of extremal black holes in anti-de Sitter space, based on gauge theory correspondence.

Contribution

It establishes the universality of the viscosity to entropy ratio at extremality for various R-charged black holes in AdS space.

Findings

Viscosity to entropy ratio is 1/(4 pi) at extremality.

Universality applies to multiple R-charged black holes.

Results support gauge/gravity duality predictions.

Abstract

Assuming gauge theory realization at the boundary, we show that the viscosity to entropy ratio is 1/(4 pi) where the bulk is represented by a large class of extremal black holes in anti-de Sitter space. In particular, this class includes multiple R-charged black holes in various dimensions.