Effect of Light Fermions on the Confinement Transition in QCD-like Theories

TL;DR

This paper investigates how light fermions influence the confinement transition in QCD-like theories, proposing a mechanism involving monopole dilution and stronger coupling, supported by lattice gauge theory insights.

Contribution

It introduces a novel explanation for the shift in confinement transition parameters due to light fermions, emphasizing monopole occupation and Bose-Einstein condensation effects.

Findings

Light fermions occupy monopoles via zero modes, affecting their distinguishability.

Dilution of monopoles is offset by increased coupling, making them lighter and more numerous.

Flavor-carrying monopole-quark objects explain excess density in dense phases.

Abstract

Dependence of the confinement transition parameters on the fermion content provides information on the mechanism of confinement. Recent progress in lattice gauge theories has allowed to study it for light flavor number $N_f\sim O(10)$ and found this transition to shift toward significantly stronger coupling. We propose an explanation for that: light fermions can occupy the chromo-magnetic monopoles, via zero modes, making them "distinguishable" and unsuitable for Bose-Einstein Condensation. Such dilution of unoccuplied monopoles is compensated by stronger coupling that makes them lighter and more numerous. We also suggest that flavor-carrying quark-monopole objects account for the density beyond quark Fermi sphere seen in cold dense phase of $N_c=2$ lattice QCD.