TWO-LOOP CROSSOVER SCALING FUNCTIONS OF THE O(N) MODEL

Using Environmentally Friendly Renormalization, we present an analytic calculation of the series for the renormalization constants that describe the equation of state for the O(N) model in the whole critical region. The solution to the beta-function equation, for the running coupling to order two loops, exhibits crossover between the strong coupling fixed point, associated with the Goldstone modes, and the Wilson–Fisher fixed point. The Wilson functions γλ, γφ and γφ2, and thus the effective critical exponents associated with renormalization of the transverse vertex functions, also exhibit nontrivial crossover between these fixed points.