Out-of-equilibrium dynamics in a gaussian trap model

TL;DR

This paper investigates out-of-equilibrium dynamics and fluctuation-dissipation violations in a Gaussian trap model, revealing transient aging effects and highlighting the non-uniqueness of effective temperature definitions.

Contribution

It provides a detailed analysis of fluctuation-dissipation violations in a Gaussian trap model, emphasizing the transient nature of aging and the non-uniqueness of effective temperature measures.

Findings

The system reaches thermal equilibrium after a quench, with aging effects being transient.

The fluctuation-dissipation ratio approaches a non-trivial limit at intermediate times.

Different definitions of effective temperature yield inconsistent results.

Abstract

The violations of the fluctuation-dissipation theorem are analyzed for a trap model with a gausssian density of states. In this model, the system reaches thermal equilibrium for long times after a quench to any finite temperature and therefore all aging effect are of a transient nature. For not too long times after the quench it is found that the so-called fluctuation-dissipation ratio tends to a non-trivial limit, thus inicating the possibility for the definition of a time scale dependent effective temperature. However, different definitions of the effective temperature yield distinct results. In particular plots of the integrated response versus the correlation function strongly depend on the way they are constructed. Also the definition of effective temperatures in the frequency domain is not unique for the model considered. This may have some implications for the interpretation of results from computer simulations and experimental determinations of effective temperatures.