Dissociation of Heavy Quarkonia in the Quark-Gluon Plasma

Using a temperature-dependent potential obtained from lattice gauge calculations, we study the stability of heavy quarkonia in the quark-gluon plasma. We find that only Υ(1S) and ηb(1S) are bound in the quark-gluon plasma, and have a small binding energy. The quark-gluon plasma may be revealed by an Υ(1S) dilepton peak with an invariant mass close to twice the current b quark mass, which is lower than the Υ(1S) mass in free space. The quarkonia Υ(1S) and ηb(1S) can dissociate by collision with quarks and gluons in the quark-gluon plasma. We evaluate the dissociation cross section of the Υ(1S) due to gluon absorption. The Υ(1S) and ηb(1S) can also dissociate spontaneously at temperatures above the dissociation temperature 1.11Tc, where Tc is the quark-gluon plasma phase transition temperature. At temperatures slightly above the dissociation temperature these states appear as resonances, which provides another signature for the quark-gluon plasma.