Convergence to a Lévy Process in the Skorohod $${{\mathcal {M}}}_1$$ and $${{\mathcal {M}}}_2$$ Topologies for Nonuniformly Hyperbolic Systems, Including Billiards with Cusps

Abstract

We prove convergence to a Levy process for a class of dispersing billiards with cusps. For such examples, convergence to a stable law was proved by Jung & Zhang. For the corresponding functional limit law, convergence is not possible in the usual Skorohod J_1 topology. Our main results yield elementary geometric conditions for convergence (i) in M_1, (ii) in M_2 but not M_1. In general, we show for a large class of nonuniformly hyperbolic systems how to deduce functional limit laws once convergence to the corresponding stable law is known.