Out-of-equilibrium generalized fluctuation-dissipation relations

TL;DR

This paper develops generalized fluctuation-dissipation relations applicable out of equilibrium, incorporating additional terms that account for interactions among system degrees of freedom, demonstrated through examples like granular systems and anomalous diffusion.

Contribution

It introduces a formalism for fluctuation-dissipation relations valid out of equilibrium, including interaction effects not present in traditional relations.

Findings

Derived fluctuation-dissipation relations with extra terms for non-equilibrium systems

Applied formalism to driven granular systems and anomalous diffusion

Showed response functions expressed via unperturbed correlation functions

Abstract

We discuss fluctuation-dissipation relations valid under general conditions even out of equilibrium. The response function is expressed in terms of unperperturbed correlation functions, where contributions peculiar to non-equilibrium can appear. Such extra terms take into account the interaction among the relevant degrees of freedom in the system. We illustrate the general formalism with two examples: driven granular systems and anomalous diffusion on comb structures.