Absence of chiral symmetry breaking in multi-flavor strongly coupled lattice gauge theories

TL;DR

This paper investigates the behavior of chiral symmetry in strongly coupled lattice gauge theories with multiple flavors, revealing a first-order transition to a symmetric phase as the flavor-to-color ratio exceeds a critical value.

Contribution

It introduces a resummation method for the hopping expansion to analyze chiral condensate formation across different flavor-to-color ratios in lattice gauge theories.

Findings

Existence of a critical $(N_F/N_C)$ ratio below which chiral symmetry is broken.

Abrupt disappearance of the condensate at the critical ratio indicating a first-order transition.

Identification of a chirally symmetric phase with a spectrum of colorless excitations.

Abstract

We consider lattice gauge theories at strong coupling with gauge group $U(N_C)$, or $SU(N_C)$ restricted to the meson sector, and coupled to $N_F$ flavors of fundamental representation staggered fermions. We study the formation of a chiral condensate by means of resummation of a hopping expansion. Different classes of graphs become dominant as the parameter $(N_F/N_C)$ is varied. By performing graph resummation we obtain an equation for determining the condensate as a function of $(N_F/N_C)$ and mass $m$. For values of $(N_F/N_C)$ below a critical value one reproduces the well-known result of the existence of a non-vanishing condensate solution in the $m=0$ limit. Above the critical $(N_F/N_C)$ value, however, no such solution exists, its abrupt disappearance indicating a first order transition to a chirally symmetric phase with composite (colorless) excitation spectrum.