Toward a theory of binary bound states in the quark-gluon plasma

Although at asymptotically high temperatures the quark-gluon plasma (QGP) is a gas of weakly interacting quasiparticles (modulo long-range magnetism), and it has quite different properties at temperatures of the order of a few times the critical temperature $T=(1–3)T_c$. As experiments and lattice simulations are now showing, in this region the QGP displays strong interactions between the constituents. In this paper we try to develop a theory of one of its consequences, namely, the properties of a large number of binary bound states, both hadronlike (colorless) and exotic (colored) bound pairs $gq$, $qq$, and $gg$. We evaluate their binding energies and zero-binding lines on the phase diagram and estimate their contribution to bulk thermodynamics (pressure). Their role in the transport properties (viscosity), emphasized in our previous paper, will be addressed elsewhere.