The onset and deconfinement transitions in two-colour QCD

TL;DR

This paper investigates phase transitions in two-colour QCD with two flavors, identifying an onset transition at low chemical potential and a deconfinement transition at higher chemical potential, highlighting the formation of a Fermi surface and BCS pairing.

Contribution

It provides evidence for two distinct phase transitions in two-colour QCD at non-zero chemical potential, including the nature of the condensates and the dominance of BCS pairing.

Findings

Onset transition occurs at mu ~ m_pi/2 with increased quark density.

Deconfinement transition occurs at higher mu, indicating a phase change.

Fermi surface formation and BCS pairing dominate beyond the deconfinement point.

Abstract

We study two-colour QCD with two flavours of Wilson fermion at non-zero chemical potential mu and zero temperature. We find evidence of two separate transitions: an onset transition at mu ~ m_pi/2 where quark number and energy densities increase from zero; and a deconfinement transition at higher mu. The mu-dependence of the number and energy densities and the diquark condensate indicate that a Fermi surface is formed and that BCS rather than Bose-Einstein condensation dominates at the quark mass considered here, especially beyond the deconfinement transition.