Spontaneous symmetry breakings in the singlet scalar Yukawa model within the auxiliary field method

Abstract

The aim of this work is to investigate the occurrence of two different spontaneous symmetry breakings at two levels of the description of fermion-scalar field model, by means of a set of gap equations and with a background field effective action. For that, we consider the Yukawa model, as a toy model for interactions between nonmassive fermions intermediated by a self-interacting real scalar field. This model has at stake two symmetries at the classical level that, as we know, might be spontaneously or dynamically broken with mass generation for the particles. The auxiliary field method is considered and it produces coupled renormalized gap equations. The effective action is then written with quantum contributions by the external background field method. We brought to light how the renormalization procedure affects the physical gaps, investigate its properties, and discuss the connection between the auxiliary fields not only to define composite states but also to compute the effective action.