On the Global Structure of Normal Forms for Slow-Fast Hamiltonian Systems

In the framework of Lie transform and the global method of averaging, the normal forms of a multidimensional slow-fast Hamiltonian system are studied in the case when the flow of the unperturbed (fast) system is periodic and the induced S^1-action is not necessarily free and trivial. An intrinsic splitting of the second term in a S^1-invariant normal form of first order is derived in terms of the Hannay-Berry connection associated with the periodic flow.