A global Nekhoroshev theorem for particles on the torus with time dependent Hamiltonian

Abstract

We prove a $C^\infty$ global version of Nekhoroshev theorem for time dependent Hamiltonians in $R^d\times T^d$. Precisely, we prove a result showing that for all times the actions of the unperturbed systems are bounded by a constant times $ \langle t\rangle^{\epsilon}$. We apply the result to the dynamics of a charged particle in $T^d$ subject to a time dependent electromagnetic field.