N=2* hydrodynamics

TL;DR

Addresses transport in strongly coupled non-conformal N=2^* gauge theory via gauge/gravity duality and the membrane paradigm. The authors compute Minkowski-space stress-tensor correlators in the finite-temperature N=2^* holographic background to extract the shear viscosity using the Kubo formula and to identify a shear-diffusion pole. They find η/s = $\frac{1}{4\pi}$ independent of the bosonic and fermionic mass parameters, with a diffusion constant D = $\frac{1}{4\pi T}$, consistent with η = s D T. The results reinforce the universality of the Kovtun-Son-Starinets bound at infinite coupling and point to future exploration with chemical potentials.

Abstract

Using gauge theory /string theory correspondence certain universal aspects of the strongly coupled four dimensional gauge theory hydrodynamics were established in hep-th/0311175. The analysis were performed in the framework of ``membrane paradigm'' approach to the fluctuations on the black brane stretched horizon. We confirm the universal result for the shear viscosity to the entropy density ratio for the strongly coupled N=2* gauge theory from explicit computation of the finite temperature Minkowski-space correlation functions in the dual supergravity geometry.