PUB - Publikationen an der Universität Bielefeld

Results of the two-loop calculation of the renormalization constant Z1 for the on-shell fermion-fermion-vector vertex function of a general gauge theory with one massive fermion and the other particles massless are presented. Computations were performed in n dimensions and for an arbitrary covariant gauge. We found Z1 to be gauge invariant in a renormalization scheme with simultaneous dimensional regularization of ultraviolet and infrared divergences. The charge renormalization constant in this scheme has ultraviolet and infrared divergences. It is found that infrared divergent terms in one- and two-loop approximation are proportional to the appropriate coefficient of the beta-function determined by ultraviolet divergences of massless particles, i.e. gluons and massless fermions.