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_r associated with the Brownian process is small compared with the mean collision time tau_c the spatial density isnearly homogeneous and the velocity probability distribution is Gaussian. In the opposite limit tau_r >> tau_c one has strong spatial clustering, with a fractal distribution of particles, and the velocity probability distribution strongly deviates from the Gaussian one.