THREE-DIMENSIONAL $\left( {\bar \psi \psi } \right)^2 $ MODEL AND OPTIMIZED EXPANSION

Abstract

An alternative way to study the (2+1)-dimensional four-fermion model using the method of optimized expansions has been proposed. Contrary to Ref. 5 we use the technique of auxiliary scalar fields. In this the interpolation Lagrangian becomes nonlinear over the parameter ε. The effective potential has been constructed with the help of the canonical optimized procedure. A similar phase structure, as in the 1/N expansion, has been predicted. The β-function of the theory has been calculated in the framework of the optimized expansion method.