J/ψ productions in nucleus-nucleus collisions at RHIC and LHC energies

Direct charmonium productions and prompt J/psi productions are studied for the central Au-Au collisions at RHIC and LHC energies, where the equilibrating partonic system is succeeded with hadronic matter in chemical nonequilibrium. Charmonium dissociation cross sections by mesons in the pseudoscalar octet and vector nonet are calculated with a QCD-based potential developed from the Buchmiffier-Tye potential. A prescription for adopting c (c) over bar radius dependence of c-(c) over bar relative-motion wave functions provides c (c) over bar dissociation cross sections by a gluon and mesons as functions of the radius. Deconfinement enhancement originating from the partonic system appears obviously in the prompt J/psi number distributions and direct charmonium. number distributions in the rapidity region -1.5 < y < 1.5 at p(T) = 4 GeV but the direct psi' at LHC energy. Such deconfinement enhancement is also found in the ratios of prompt J/psi and direct charmonium number distributions to the initially yielded number distributions for Au-Au collisions or to nucleon-nucleon collisions at the RHIC energy. Twists in the prompt J/psi and direct charmonium number distributions and the ratios in -1.5 < y < 1. 5 show the existence of partonic system at the LHC energy. (C) 2002 Elsevier Science B.V. All rights reserved.