Massless propagators: applications in QCD and QED

Abstract

We report on two recent results based on the evaluation of five-loop massless propagators in QCD and QED: (i) corrections of order ${\alpha }_s^4$ to the absorptive part of the polarization function in QCD with $n_f=3$;(ii) the five-loop contribution to the $\beta$ function of quenched QED.

Comments: 7 pages, contribution to the 8-th International Symposium on Radiative Corrections (RADCOR), October 1-5 2007, Florence, Italy