Nenciu Gheorghe, Sordoni Vania
Semiclassical limit for multistate Klein-Gordon systems: almost
invariant subspaces and scattering theory.
(70K, LATeX 2e)

ABSTRACT.  Using the method of Helffer and Sj\"ostrand  we construct almost
invariant subspaces for multicomponent Klein-Gordon  hamiltonians.
As  an application, we prove that, in the semiclassical limit and for
analytic potentials, the scattering operator is block diagonal up to
exponentially small errors.