Widths of quarkonia in quark gluon plasma

Recent lattice calculations showed that heavy quarkonia will survive beyond the phase-transition temperature and will dissolve at different temperatures depending on the type of the quarkonium. In this work, we calculate the thermal width of a quarkonium at finite temperature before it dissolves into open heavy quarks. The input of the calculation are the parton quarkonium dissociation cross section to next-to-leading order in quantum chromodynamics (QCD), the quarkonium wave function in a temperature-dependent potential from lattice QCD, and a thermal distribution of partons with thermal masses. We find that for the J/psi, the total thermal width above 1.4T(c) becomes larger than 100 to 250 MeV, depending on the effective thermal masses of the quark and gluon, which we take between 400 and 600 MeV. Such a width corresponds to an effective dissociation cross section by gluons between 1.5 and 3.5 mb and by quarks 1 to 2 mb at 1.4T(c). However, at similar temperatures, we find a much smaller thermal width and effective cross section for the Upsilon.