Evidence for a conformal phase in SU(N) gauge theories

TL;DR

This study provides evidence for a conformal phase in SU(3) gauge theories with 12 flavors, indicating an infrared fixed point and chiral symmetry restoration, which refines the understanding of the conformal window in QCD-like theories.

Contribution

First lattice study to identify a conformal phase in SU(3) gauge theories with 12 flavors, supporting the existence of an infrared fixed point and constraining the conformal window.

Findings

Chiral symmetry is restored at zero temperature.

Presence of a Coulomb-like phase suggests an infrared fixed point.

The conformal window likely begins before 12 flavors.

Abstract

We discuss the existence of a conformal phase in SU(N) gauge theories in four dimensions. In this lattice study we explore the model in the bare parameter space, varying the lattice coupling and bare mass. Simulations are carried out with three colors and twelve flavors of dynamical staggered fermions in the fundamental representation. The analysis of the chiral order parameter and the mass spectrum of the theory indicates the restoration of chiral symmetry at zero temperature and the presence of a Coulomb-like phase, depicting a scenario compatible with the existence of an infrared stable fixed point at nonzero coupling. Our analysis supports the conclusion that the onset of the conformal window for QCD-like theories is smaller than Nf=12, before the loss of asymptotic freedom at sixteen and a half flavors. We discuss open questions and future directions.