Five-loop fermion anomalous dimension for a general gauge group from four-loop massless propagators

We extend the O(α$\substack{5\\s}$) result of the analytic calculation of the quark mass anomalous dimension in pQCD [1] to the case of a generic gauge group. We present explicit formulas which express the relevant renormalization constants in terms of fourloop massless propagators. We also use our result to shed new light on the old puzzle of the absence of even zetas in results of perturbative calculations for a class of physical observables.