Shear transport far from equilibrium via holography

Abstract

In heavy-ion collisions, the quark-gluon plasma is produced far from equilibrium. This regime is currently inaccessible by quantum chromodynamics (QCD) computations. We calculate shear transport and entropy far from equilibrium in a holographic model, defining a time-dependent ratio of shear viscosity to entropy density, $\eta /s$. Large deviations of up to 60% from its near-equilibrium value, $1/4\pi$, are found for realistic situations at the Large Hadron Collider. We predict the far-from-equilibrium time-dependence of $\eta /s$ to substantially affect the evolution of the QCD plasma and to impact the extraction of QCD properties from flow coefficients in heavy-ion collision data.

Comments: 10 pages, 4 figures