title: Quasistationary states and the range of pair interactions.
abstract: "Quasistationary" states are approximately time independent out of equilibrium states which have been observed in a variety of systems of particles interacting by long-range interactions. We investigate here the conditions of their occurrence for a generic pair interaction V(r→∞)~1/r(γ) with γ>0, in d>1 dimensions. We generalize analytic calculations known for gravity in d=3 to determine the scaling parametric dependences of their relaxation rates due to two-body collisions, and report extensive numerical simulations testing their validity. Our results lead to the conclusion that, for γ<d-1, the existence of quasistationary states is ensured by the large distance behavior of the interaction alone, while for γ>d-1 it is conditioned on the short distance properties of the interaction, requiring the presence of a sufficiently large soft core in the interaction potential.
authors.affiliation: SMC, CNR-INFM, Physics Department, University Sapienza of Rome, Piazzale Aldo Moro 2, 00185-Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Gabrielli
authors.forename: M
authors.initials: M
authors.lastname: Joyce
authors.forename: B
authors.initials: B
authors.lastname: Marcos