Gluo-dissociation of heavy quarkonium in the quark-gluon plasma reexamined

摘要

Using an effective Hamiltonian derived from the QCD multipole expansion, we calculate the cross sections of gluo-dissociation of heavy quarkonia in the quark-gluon plasma, by including both the chromo-electric dipole (E_1) and the chromo-magnetic dipole (M_1) transition mechanisms. While the former allows us to reproduce the results from operator-product-expansion calculations in the Coulomb approximation, the latter as a novel contribution is shown to be significant at low energies close to the threshold. Using thus obtained cross sections, we further carry out a full calculation of the gluo-dissociation rates for various charmonia and bottomonia within a nonrelativistic in-medium potential model. The M_1 contribution turns out to be most prominent for the J/ψ and accounts for ~10%-25% of the total (E1 +M1) dissociation rate at temperatures close to the transition temperature.