Dissociation of a Heavy Quarkonium at T<T_c

We examine three different ways a heavy quarkonium can dissociate at temperatures below the quark-gluon plasma phase transition temperature T_c: spontaneous dissociation, dissociation by thermalization, and dissociation by collision with hadrons. We evaluate the cross sections for the dissociation of J/psi and Upsilon in collision with pion as a function of temperature, using the quark-interchange model of Barnes and Swanson. We also evaluate the dissociation temperatures for various quarkonia, and the fraction of quarkonium lying above the dissociation threshold as a function of temperature, using an interquark potential inferred from lattice gauge calculations.