title: Correlations in ballistic processes.
abstract: We investigate a class of reaction processes in which particles move ballistically and react upon colliding. We show that correlations between velocities of colliding particles play a crucial role in the long time behavior. In the reaction-controlled limit when particles undergo mostly elastic collisions and therefore are always near equilibrium, the correlations are accounted analytically. For ballistic aggregation, for instance, the density decays as n approximately t(-xi) with xi=2d/(d+3) in the reaction-controlled limit in d dimensions, in contrast with the well-known mean-field prediction xi=2d/(d+2).
authors.affiliation: Laboratoire de Physique Théorique (UMR 8627 du CNRS), Bâtiment 210, Université Paris-Sud, 91405 Orsay, France. Emmanuel.Trizac@th.u-psud.fr
authors.forename: E
authors.initials: E
authors.lastname: Trizac
authors.forename: P L
authors.initials: PL
authors.lastname: Krapivsky