Lattice simulations with eight flavors of domain wall fermions in SU(3) gauge theory

TL;DR

This study explores the properties of an SU(3) gauge theory with eight flavors of fermions, analyzing its spectrum and chiral behavior to understand whether it exhibits chiral symmetry breaking or conformality.

Contribution

First lattice study of Nf=8 SU(3) gauge theory using domain wall fermions, examining spectrum, chiral condensate, and electroweak parameters to identify symmetry breaking or conformality.

Findings

Evidence suggests spontaneous chiral symmetry breaking.

Chiral condensate is significantly enhanced relative to the decay constant F.

The S parameter is reduced, indicating parity doubling similar to Nf=6 results.

Abstract

We study an SU(3) gauge theory with Nf=8 degenerate flavors of light fermions in the fundamental representation. Using the domain wall fermion formulation, we investigate the light hadron spectrum, chiral condensate and electroweak S parameter. We consider a range of light fermion masses on two lattice volumes at a single gauge coupling chosen so that IR scales approximately match those from our previous studies of the two- and six-flavor systems. Our results for the Nf=8 spectrum suggest spontaneous chiral symmetry breaking, though fits to the fermion mass dependence of spectral quantities do not strongly disfavor the hypothesis of mass-deformed infrared conformality. Compared to Nf=2 we observe a significant enhancement of the chiral condensate relative to the symmetry breaking scale F, similar to the situation for Nf=6. The reduction of the S parameter, related to parity doubling in the vector and axial-vector channels, is also comparable to our six-flavor results.