Perturbative infrared finiteness of Yang-Mills theory from renormalization group flow

It is commonly believed that a Yang-Mills theory (and in general a massless theory) with a non-vanishing subtraction point is infrared finite, i.e. the vertex functions at non-exceptional momenta are finite. We give a simple perturbative proof of this fact by using the Wilson renormalization group formulation. The proof requires the control of the singular behaviour of vertex functions only for a restricted class of exceptional configurations of momenta. ((orig.))