Non-equilibrium fluctuation-dissipation relation from holography

TL;DR

This paper derives a universal non-equilibrium fluctuation-dissipation relation using holography, applicable to strongly coupled systems out of equilibrium, with potential experimental tests in heavy ion collisions.

Contribution

It introduces a generalized fluctuation-dissipation relation for non-equilibrium states derived from holography, extending thermal relations to out-of-equilibrium conditions.

Findings

Universal relation holds for non-equilibrium states from thermal equilibrium.

Applicable to systems described by holography in the classical gravity limit.

Potential for experimental verification in heavy ion collision experiments.

Abstract

We derive a non-equilibrium fluctuation-dissipation relation for bosonic correlation functions from holography in the classical gravity approximation at strong coupling. This generalizes the familiar thermal fluctuation-dissipation relation in absence of external sources. This also holds universally for any non-equilibrium state which can be obtained from a stable thermal equilibrium state in perturbative derivative (hydrodynamic) and amplitude (non-hydrodynamic) expansions. Therefore, this can provide a strong experimental test for the applicability of the holographic framework. We discuss how it can be tested in heavy ion collisions. We also make a conjecture regarding multi-point holographic non-equilibrium Green's functions.