Quark mass anomalous dimension at O(1/Nf2) in QCD

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 <(MS)over bar> quark mass anomolous dimension at five loops is deduced and compared with the numerical asymptotic Pade approximant prediction. (C) 1999 Published by Elsevier Science B.V. All rights reserved.