Morbidelli A., Giorgilli A.
Superexponential stability of KAM tori
(47K, TeX)

ABSTRACT.  We study the dynamics in the neighbourhood of an invariant
torus of a nearly integrable system. We provide an upper bound to the
diffusion speed, which turns out to be of superexponentially small size
$\exp(\exp(-1/\rho))$, $\rho$ being the distance from
the invariant torus. We also discuss the connection of this result with
the existence of many invariant tori close to the considered one.