Mesoscopic Model of Aging in Colloids

A model of dense hard sphere colloids building on simple notions of particle mobility and spatial coherence is presented and shown to reproduce results of experiments and simulations for key quantities such as the intermediate scattering function, the particle mean-square displacement and the χ4 mobility correlation function. All results are explained by two emerging and interrelated dynamical properties: i) a rate of intermittent events, quakes, which decreases as the inverse of the system age t, leading to μq(tw, t) α log(t/tw) as the average number of quakes occurring between the ‘waiting time’ tw and the current time t; ii) a length scale characterizing correlated domains, which increases linearly in log t.