The coupling of quark and gluon condensates in dense systems

Abstract

Two lagrangians, which implement the QCD scale anomaly, are used to study the coupling of quark and gluon condensates in dense baryonic matter. We show both numerically and analytically that the behaviour of the system depends crucially on the assumed value of the vacuum quark condensate. For a low value, compatible with the bag constant, the gluon condensate “feels” the chiral phase transition. With a higher value, deduced from QCD sum rules, the gluon condensate decouples from the quark condensate and does not change appreciably across the chiral phase transition. In one of the lagrangians, the pion mass drops gradually to zero as the phase transition is approached.