On Gevrey regularity of globally C hypoelliptic operators

We prove Gevrey regularity for a class of operators defined on the torus T^(m+n), with real analytic coefficients in T^m, and which are globally C^(infinity) hypoelliptic. Then, we apply this result to show global G^s hypoellipticity for a large class of sublaplacians that may include lower order terms.