Effective Polyakov loop models for QCD-like theories at finite chemical potential

TL;DR

This paper develops effective Polyakov loop models for QCD-like theories at finite chemical potential, revealing phase transitions such as Bose-Einstein condensation and fermionic liquid-gas transitions in two-color and G2-QCD.

Contribution

It introduces derived three-dimensional Polyakov-loop effective theories from strong-coupling and hopping expansions to study finite density effects in QCD-like theories.

Findings

Evidence of a zero-temperature transition to diquark density in two-color QCD.

Observation of a second transition in G2-QCD density related to nucleon formation.

Identification of phase transition behaviors depending on the gauge group.

Abstract

We study genuine finite density effects in QCD-like theories with three-dimensional Polyakov-loop effective theories for heavy quarks. These are derived from the full QCD-like theories by combined strong-coupling and hopping expansions. In particular, we investigate the cold and dense regimes of phase diagrams where we expect to find Bose-Einstein-condensation of diquark baryons or a fermionic first-order liquid-gas transition, depending on the gauge group of the theory. In two-color QCD, for example, we observe evidence of a continuous zero-temperature transition to finite diquark density when the quark chemical potential $\mu$ reaches half the diquark mass, i.e. without binding energy. In G$_2$-QCD we observe, in addition to this "Silver Blaze" onset of diquark density, a second transition in the density towards an exponential increase by roughly $3\mu/T$ corresponding to a finite density of G$_2$-nucleons.