Lattice Study on quantum-mechanical dynamics of two-color QCD with six light flavors

TL;DR

This lattice study explores the chiral properties of SU(2) gauge theory with six light flavors, providing evidence that chiral symmetry may not spontaneously break in this system, suggesting different long-distance dynamics.

Contribution

The paper presents the first lattice simulation evidence indicating the absence of spontaneous chiral symmetry breaking in SU(2) gauge theory with six flavors.

Findings

Chiral symmetry does not spontaneously break in the six-flavor system.

The mesonic spectrum's quark mass dependence supports this.

Finite size effects increase the decay constant, contrary to chiral perturbation theory predictions.

Abstract

We investigate the chiral properties of SU(2) gauge theory with six flavors, i.e. six light Dirac fermions in the fundamental representations by lattice simulation, and point out that the spontaneous breakdown of chiral symmetry does not occur in this system. The quark mass dependence of the mesonic spectrum provides an evidence for such a possibility. The decay constant tends to be increased by the finite size effect, which is opposite to the behavior predicted by chiral perturbation theory and indicates that the long distance dynamics in the six-flavor theory could be different from the theory with chiral symmetry breaking. The subtracted chiral condensate, whose utility is demonstrated by the simulation of two-flavor theory, is shown to vanish in the chiral limit within the precision of available data.