Andrei Starinets

Abstract:

The ratio of shear viscosity to volume density of entropy can be used to characterize how close a given fluid is to being perfect. Using string theory methods, we show that this ratio is equal to a universal value of ℏ/4πkB for a large class of strongly interacting quantum field theories whose dual description involves black holes in anti-de Sitter space. We provide evidence that this value may serve as a lower bound for a wide class of systems, thus suggesting that black hole horizons are dual to the most ideal fluids. © 2005 The American Physical Society.

Abstract:

Gauge theory-gravity duality predicts that the shear viscosity of N = 4 supersymmetric SU(Nc) Yang-Mills plasma at temperature T in the limit of large N c and large 't Hooft coupling gYM²Nc is independent of the coupling and equals to πNc²T³ /8. In this paper, we compute the leading correction to the shear viscosity in inverse powers of 't Hooft coupling using the α′-corrected low-energy effective action of type IIB string theory. We also find the correction to the ratio of shear viscosity to the volume entropy density (equal to 1/4π in the limit of infinite coupling). The correction to 1/4π scales as (gYM²Nc) ^-3/2 with a positive coefficient. © 2004 Elsevier B.V. All rights reserved.