From confinement to new states of dense matter in quantum chromodynamics

Transitions between centre sectors are related to confinement in pure Yang–Mills theories. We study the impact of these transitions in QCD (quantum chromodynamics) like theories for which the centre symmetry is explicitly broken by the presence of matter. For low temperatures, we provide numerical evidence that centre transitions do occur, with matter merely providing a bias towards the trivial centre sector until the centre symmetry is spontaneously broken at high temperatures. The phenomenological consequences of these transitions for dense hadron matter are illustrated in the Schwinger model and an SU(3) effective quark theory: centre-dressed quarks undergo condensation due to Bose-type statistics, forming a hitherto unknown state of dense but cold quark matter.