J/ψ suppression and pT spectra in RHIC and LHC energy collisions

In a hydrodynamic model, we have studied J/ψ production in Au+Au/Cu+Cu collisions at RHIC energy, √(s)=200 GeV. At the initial time, J/ψ's are randomly distributed in the fluid. As the fluid evolves in time, the free streaming J/ψ's are dissolved if the local fluid temperature exceeds a threshold temperature TJ/ψ. Sequential melting of charmonium states (χc, ψ' and J/ψ), with melting temperatures Tχc=Tψ'∼1.2Tc, TJ/ψ∼2Tc and feed-down fraction F∼0.3, explains the PHENIX data on the centrality dependence of J/ψ suppression in Au+Au collisions. J/ψ pT spectra and the nuclear modification factor in Au+Au collisions are also well explained in the model. The model however overpredicts the centrality dependence of J/ψ suppression in Cu+Cu collisions by 20-30%. The J/ψ pT spectra are underpredicted by 20-30%. The model predicts that in central Pb+Pb collisions at LHC energy, √(s)=5500 GeV, J/ψ's are suppressed by a factor of ∝10. The model predicted a J/ψ pT distribution in Pb+Pb collisions at LHC is similar to that in Au+Au collisions at RHIC. (orig.)