Aging at Criticality in Model C Dynamics

TL;DR

This paper analyzes the off-equilibrium critical response and correlation functions in Model C dynamics of the O(N) vector model, revealing aging behavior and fluctuation-dissipation ratios through epsilon expansion.

Contribution

It provides the first epsilon-expansion calculation of two-point functions and fluctuation-dissipation ratios for Model C, extending understanding of aging at criticality.

Findings

Scaling forms determined up to first order in epsilon

Fluctuation-dissipation ratio matches Model A for N=1

Aging regime exhibits non-trivial large time limit

Abstract

We study the off-equilibrium two-point critical response and correlation functions for the relaxational dynamics with a coupling to a conserved density (Model C) of the O(N) vector model. They are determined in an \epsilon=4-d expansion for vanishing momentum. We briefly discuss their scaling behaviors and the associated scaling forms are determined up to first order in epsilon. The corresponding fluctuation-dissipation ratio has a non trivial large time limit in the aging regime and, up to one-loop order, it is the same as that of the Model A for the physically relevant case N=1. The comparison with predictions of local scale invariance is also discussed.