Shear viscosity in weakly coupled $\mathcal{N}=4$ Super Yang-Mills theory compared to QCD

Abstract

We compute the shear viscosity of weakly coupled N=4 supersymmetric Yang-Mills (SYM) theory. Our result for [eta/s], the viscosity to entropy-density ratio, is many times smaller than the corresponding weak-coupling result in QCD. This suggests that [eta/s] of QCD near the transition point is several times larger than the viscosity bound, [eta/s] >= 1/4 pi.

Comments: 4 pages with 3 figures. References are corrected and minor changes are made. Conclusions unchanged