Heavy quarkonia and quark drip lines in quark–gluon plasma

Abstract

Using the potential model and thermodynamical quantities obtained in lattice gauge calculations, we determine the spontaneous dissociation temperatures of colour-singlet quarkonia and the ‘quark drip lines’ which separate the region of bound quarkonium states from the unbound region. The dissociation temperatures of J/ψ and χb in quenched QCD are found to be 1.62Tc and 1.18Tc respectively, in good agreement with spectral function analyses. The dissociation temperature of J/ψ in full QCD with two flavours is found to be 1.42Tc. For possible bound quarkonium states with light quarks, the characteristics of the quark drip lines severely limit the stable region close to the phase transition temperature. Bound colour-singlet quarkonia with light quarks may exist very near the phase transition temperature if their effective quark mass is of the order of 300–400 MeV.