Eur. Phys. J. C (2009) 61: 331-338
https://doi.org/10.1140/epjc/s10052-009-0963-9

Regular Article - Theoretical Physics

J/ψ suppression and p _T spectra in RHIC and LHC energy collisions

Variable Energy Cyclotron Centre, 1/AF, Bidhan Nagar, Kolkata, 700 064, India

^* e-mail: akc@veccal.ernet.in

Received: 23 August 2008
Revised: 24 November 2008
Published online: 28 March 2009

Abstract

In a hydrodynamic model, we have studied J/ψ production in Au+Au/Cu+Cu collisions at RHIC energy, 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 T _J/ψ . Sequential melting of charmonium states (χ _c , ψ ^′ and J/ψ), with melting temperatures , T _J/ψ ≈2T _c 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 p _T 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 p _T spectra are underpredicted by 20–30%. The model predicts that in central Pb+Pb collisions at LHC energy,  GeV, J/ψ’s are suppressed by a factor of ∼10. The model predicted a J/ψ p _T distribution in Pb+Pb collisions at LHC is similar to that in Au+Au collisions at RHIC.