ON THE 0(1/N2) BETA-FUNCTION OF THE NAMBU-JONA-LASINIO MODEL WITH NON-ABELIAN CHIRAL-SYMMETRY

We present the formalism for computing the critical exponent corresponding to the beta-function of the Nambu-Jona-Lasinio model with SU (M) x SU (M) continuous chiral symmetry at 0(1/N2) in a large N expansion, where N is the number of fermions. We find that the equations can only be solved for the case M = 2 and subsequently an analytic expression is then derived. This contrasting behaviour between the M = 2 and M > 2 cases, which appears first at O(1/N2), is related to the fact that the anomalous dimensions of the bosonic fields are only equivalent for M = 2.