Spontaneous symmetry breaking without classical fields: A functional renormalization group approach

Abstract

We propose an approach to describe spontaneous symmetry breaking that does not rely on the order parameter dependent free energy (Landau theory). We use the functional renormalization group evolution of the explicitly broken theory, using a truncation scheme that is compatible with the Ward identities. To represent the symmetry breaking, we propose to use the ``Ward ratio'' which is zero in the symmetric phase and unity in the broken phase. In this approach a unified scale evolution of the effective potential is applicable in both phases. It is peculiar that the scale evolution is accelerated in the critical regime.