Quark mass anomalous dimension at O(1/N_f^2) in QCD

Abstract

We compute the d-dimensional critical exponents corresponding to the wave function and mass renormalization of the quark in QCD in the Landau gauge at a new order, O(1/N_f^2), in the large N_f expansion. The computations are simplified by the establishment in d-dimensions of the critical point equivalence of QCD and the non-abelian Thirring model beyond leading order. The form of the O(1/N_f^2) coefficients in the MSbar quark mass anomalous dimension at five loops is deduced and compared with the numerical asymptotic Pade approximant prediction.