Hot and dense hadronic matter - selected topics -

Abstract

Recent developments in the area of hadronic and quark-gluon matter under extreme conditions are surveyed. A prime topic is the possible interplay of chiral and deconfinement transitions in QCD. The symmetry breaking pattern of QCD features two seemingly disconnected phenomena: the spontaneous breakdown of the Z(3) center symmetry in the deconfinement transition of pure-gauge QCD, and the spontaneous breaking of chiral SU(Nf) ×SU(Nf) symmetry in the limit of Nf massless quark flavors. The dynamical entanglement of these symmetries is discussed in the framework of a schematic model (the PNJL model) in comparison with results from lattice QCD. The QCD phase diagram is also explored from this viewpoint, with emphasis on the (uncertain) location of the critical point. Aspects of compressed baryonic matter at zero temperature and its nuclear physics connection are sketched in view of new results for the density dependence of the chiral condensate.