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We calculate the mass shift and thermal decay width of the J / ψ near the QCD transition temperature T c by imposing two independent constraints on these variables that can be obtained first by solving the Schrodinger equation and second from the QCD sum rule approach. While the real part of the potential is determined by comparing the QCD sum rule result for charmonium and the D meson to that from the potential model result, the imaginary potential is taken to be proportional to the perturbative form multiplied by a constant factor, which in turn can be determined by applying the two independent constraints. The result shows that the binding energy and the thermal width becomes similar in magnitude at around T = 1.09 T c , above which the sum rule analysis also becomes unstable, strongly suggesting that the J / ψ will melt slightly above T c .

Based on a kinetic description of J / ψ dissociation and production in an expanding quark–gluon plasma that is described by a 2 + 1 dimensional ideal hydrodynamics, we have studied the hot medium effects on J / ψ production in p + Pb collisions at s NN = 5.02 TeV . Including also the cold nuclear matter effects, we are able to reproduce recent experimental results on the nuclear modification factor R p Pb ( J / ψ ) measured by the ALICE Collaboration. We have also made predictions for the R p Pb of J / ψ and the double ratio R p Pb pro ( ψ ′ ) / R p Pb pro ( J / ψ ) of prompt quarkonia produced in the most central 10% p + Pb collisions. We find that different from the cold nuclear matter effects, the R p Pb ( J / ψ ) is slightly smaller than that in the minimum bias collisions, and the double ratio is significantly less than one at backward rapidity.

The velocity dependence of the thermal width of heavy quarkonia traveling with respect to the quark gluon plasma is calculated up to the NLO in perturbative QCD. At the LO, the width decreases with increasing speed, whereas at the NLO it increases with a magnitude approximately proportional to the expectation value of the relative velocity between the quarkonium and a parton in thermal equilibrium. Such an asymptotic behavior is due to the NLO dissociation cross section converging to a nonvanishing value in the high energy limit., Comment: 8 pages, 4 figures, references addes. version to be published in Phys. Lett. B

We study the changes in the partial decay widths of excited charmonium states into $D \bar{D}$, when the D meson mass decreases in nuclear matter, taking the internal structure of the hadrons into account. Calculations within the 3P0 model for $\psi(3686)$ and $\psi(3770)$ imply that naive estimates of the in-medium widths based only on phase space are grossly exaggerated. Due to nodes in the wave functions, these states may even become narrow at high densities, if the D meson mass is decreased by about 200 MeV. For the $\chi$ states, we generally expect stronger modifications of the widths. The relevance of the $\chi$ widths for $J/\psi$ suppression in heavy ion collision is discussed. These phenomena could be explored in experiments at the future accelerator facility at GSI., Comment: 12 pages, 3 figures; allowed for two independent oscillator parameters for the charmonium states and D mesons, results are not significantly modified and conclusions remains unaltered