Cooperative Rearrangements in Aging Colloidal Glass Simulations: Log-Poisson Statistics

Physical aging is a non-equilibrium relaxation process which takes place after a system is quenched into a glassy state. One of the unexplained features of aging is that the process stagnates on a non-exponential time scale. We posit that the intermittent, irreversible rearrangements noted in aging colloidal glasses are permitted by record-breaking fluctuations of local dynamics. If such events are the sole mechanism of relaxation, this would make aging appear as a Poisson process when viewed on a logarithmic time scale. We examine data from MD simulations, an experimental system, and a coarse grained model. We show that the age-dependent rate of rearrangement events is consistent with a Log-Poisson process, and thus provide a possible explanation for the anomalous time-dependence of dynamical properties of a wide variety of glassy systems.