A heavy quark–antiquark pair in hot QCD

Abstract Thermodynamics of a heavy quark–antiquark pair in SU ( 3 ) -QCD is studied both below and above the deconfinement critical temperature T c . In the quenched case, a model of the string passing through heavy valence gluons yields a correct estimate of T c and the critical behavior of the string tension below T c . For two light flavors, entropy and internal energy below T c can be obtained from the partition function of heavy–light mesons and baryons. To calculate the free energy of the system above T c , we apply second-order perturbation theory in the interaction of the quark–gluon plasma constituents with the static quark–antiquark pair. The results for the entropy and internal energy, obtained both below and above T c , are compared with recent lattice data.