On the consistent solution of the gap--equation for spontaneously broken $\lambda {\Phi }^4$-theory

Abstract

We present a self--consistent solution of the finite temperature gap--equation for $\lambda {\Phi }^4$ theory beyond the Hartree-Fock approximation using a composite operator effective action. We find that in a spontaneously broken theory not only the so--called daisy and superdaisy graphs contribute to the resummed mass, but also resummed non--local diagrams are of the same order, thus altering the effective mass for small values of the latter.

Comments: 15 pages of revtex + 3 uuencoded postscript figures, ENSLAPP A-488/94