Abstract
We prove time decay estimates for several kinetic equations like the free lkansport, Boltzmann and Vlasov—Poisson Equations. We also consider solutions with infinite energy of the Vlasov—Poisson Equation and we show that low moments in the velocity variable are propagated. As a consequence, we prove that the potential energy becomes finite immediately and that the kinetic energy is locally finite. Our approach is based on new dispersive identities for transport equations.