RG Equations and High Energy Behaviour in Non-Renormalizable Theories.

We suggest a novel view on non-renormalizable interactions. It is based on the usual BPHZ R-operation which is equally applicable to any local QFT independently whether it is renormalizable or not. As a playground we take the phi^4_D theory in D dimensions for D=4,6,8,10 and consider the four-point scattering amplitudeon shell. We derive the generalized RG equation and find the solution valid for any D that sums up the leading logarithms in all orders of PT in full analogy with the renormalizable case. It is found that the scattering amplitudein the phi^4_D theory possesses the Landau poleat high energy for any D. We discuss the application of the proposed procedure to other non-renormalizable theories.