Coarsening in cooling granular gases
Consider a collection of ballistically moving particles that cools down through inelastic collisions. During this process, the particles cluster together with the mean cluster size increasing with time. This coarsening behaviour is studied in one and two dimensions, and in certain time regimes, is shown to be of a different nature from what is seen in conventional spin systems. This anomaly is traced to the behaviour of velocity fluctuations within a cluster.