Mesoscopic fluctuations and intermittency in aging dynamics

Fysisk Institut, SDU - DK-5230 Odense M, Denmark

Received: 7 June 2005
Accepted: 27 October 2005

Abstract

Mesoscopic aging systems are characterized by large intermittent noise fluctuations. In a record dynamics scenario (Sibani P. and Dall J., Europhys. Lett., 64 (2003) 8) these events, quakes, are treated as a Poisson process with average , where t is the observation time, t_w is the age and α is a parameter. Assuming for simplicity that quakes constitute the only source of de-correlation, we present a model for the probability density function (PDF) of the configuration autocorrelation function. Beside α, the model has the average quake size as a parameter. The model autocorrelation PDF has a Gumbel-like shape, which approaches a Gaussian for large and becomes sharply peaked in the thermodynamic limit. Its average and variance, which are given analytically, depend on as a power law and a power law with a logarithmic correction, respectively. Most predictions are in good agreement with data from the literature and with the simulations of the Edwards-Anderson spin-glass carried out as a test.