EFFECTIVE POTENTIAL FOR LOCAL COMPOSITE-OPERATORS AND THE PROBLEM OF FACTORIZATION OF MULTIFIELD CONDENSATES

A new formulation of effective potential for local composite operators is given. The two-fermion condensate {Mathematical expression} and four-fermion condensate {Mathematical expression} are calculated simultaneously in the Gross-Neveu model up to next-to-the-leading order in 1/N expansion. It is shown that factorization {Mathematical expression} holds only in the N→∞ limit and the non-factorized part of {Mathematical expression} contributed by the order-1/N terms is comparable to {Mathematical expression} when taking N=3. © 1990 Springer-Verlag.