Andrei Starinets

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.

Abstract:

We show that long-time, long-distance fluctuations of plane-symmetric horizons exhibit universal hydrodynamic behavior. By considering classical fluctuations around black-brane backgrounds, we find both diffusive and shear modes. The diffusion constant and the shear viscosity are given by simple formulas, in terms of metric components. For a given metric, the answers can be interpreted as corresponding kinetic coefficients in the holographically dual theory. For the near-extremal DP, M2 and M5 branes, the computed kinetic coefficients coincide with the results of independent AdS/CFT calculations. In all the examples, the ratio of shear viscosity to entropy density is equal to ℏ/(4πkB, suggesting a special meaning of this value. © SISSA/ISAS 2003.