Clustering and Non-Gaussian Behavior in Granular Matter
  We investigate the properties of a model of granular matter consisting of $N$ Brownian particles on a line subject to inelastic mutual collisions. This model displays a genuine thermodynamic limit for the mean values of the energy and the energy dissipation. When the typical relaxation time $\tau$ associated with the Brownian process is small compared with the mean collision time $\tau_c$ the spatial density is nearly homogeneous and the velocity probability distribution is gaussian. In the opposite limit $\tau \gg \tau_c$ one has strong spatial clustering, with a fractal distribution of particles, and the velocity probability distribution strongly deviates from the gaussian one. 
A. Puglisi (Univ. ''La Sapienza'' Roma), V. Loreto (ESPCI - Paris), U.   Marini Bettolo Marconi (Univ. di Camerino), A. Petr...