The QCD beta-function at O(1/N_f)

Abstract

The leading order coefficients of the beta-function of QCD are computed in a large N_f expansion. They are in agreement with the three loop MSbar calculation. The method involves computing the anomalous dimension of the operator (G^2_{mu nu})^2 at the d-dimensional fixed point in the non-abelian Thirring model to which QCD is equaivalent in this limit. The effect the O(1/N_f) corrections have on the location of the infrared stable fixed point for a range of N_f is also examined.