Two-loop coupling constant renormalization in lattice SU(N)×SU(N) 2 D chiral models

For the most general link action of lattice SU(N)×SU(N) two dimensional chiral models, the two loop coupling constant renormalization is discussed in the context of the background field method. A non-linear reparametrization of the fields, necessary to keep the invariance of the theory, introduces unpleasant extra-terms. However some of the non-universal contributions are unaffected by these extra-terms and can be easily calculated. This allows to compute the difference between the first non-universal coefficients of the Callan-Symanzik beta function for two actions having the same scale Λ. © 1986 Springer-Verlag.