Abstract :
The ratio of shear viscosity to entropy density in a strongly coupled CFT plasma can be computed using the AdS/CFT correspondence either from equilibrium correlation functions or from the Janik–Peschanski dual of the boost invariant plasma expansion. We point out that the previously found disagreement for image at finite ʹt Hooft coupling is resolved once the incoming-wave boundary condition for metric fluctuations at the horizon of the dual geometry is properly imposed.
