Shear viscosity of pure Yang-Mills theory at strong coupling

TL;DR

This paper computes the shear viscosity to entropy density ratio in pure Yang-Mills theory at strong coupling near the phase transition, finding results consistent with the AdS/CFT bound.

Contribution

It provides the first strong coupling expansion calculation of the eta/s ratio in pure Yang-Mills theory near the critical temperature.

Findings

eta/s ratio around 0.22 for N=2

eta/s ratio scales as 0.028N^2 for N>2

Results align with the 1/4pi lower bound

Abstract

We calculate the shear viscosity to entropy density ratio in pure SU(N) Yang-Mills theory below the critical temperature using the strong coupling expansion. The result for the eta/s ratio for temperatures around the phase transition is 0.22 for N = 2 and 0.028N^2 for N > 2. The results are consistent with the conjectured 1/4pi lower bound inspired by the AdS/CFT correspondence.