PERTURBATIVE RENORMALIZATION AND INFRARED FINITENESS IN THE WILSON RENORMALIZATION-GROUP - THE MASSLESS SCALAR CASE

A new proof of perturbative renormalizability and infrared finiteness for a scalar massless theory is obtained from a formulation of renorma lized field theory based on the Wilson renormalization group. The loop expansion of the renormalized Green functions is deduced from the Pol chinski equation of renormalization group. The resulting Feynman graph s are organized in such a way that the loop momenta are ordered. It is then possible to analyse their ultraviolet and infrared behaviours by iterative methods. The necessary subtractions and the corresponding c ounterterms are automatically generated in the process of fixing the p hysical conditions for the ''relevant'' vertices at the normalization point. The proof of perturbative renormalizability and infrared finite ness is simply based on dimensional arguments and does not require the usual analysis of topological properties of Feynman graphs.