Eur. Phys. J. C (2009) 61: 865-870
https://doi.org/10.1140/epjc/s10052-009-0906-5

Regular Article - Theoretical Physics

Can the RHIC J/ψ puzzle(s) be settled at LHC?

¹ Department of Physics, University of Oslo, 0318, Oslo, Norway
² Laboratoire de Physique Théorique, Unité Mixte de Recherche UMR n° 8627—CNRS, Université de Paris XI, Bâtiment 210, 91405, Orsay Cedex, France
³ Departamento de Física de Partículas, Universidad de Santiago de Compostela, 15782, Santiago de Compostela, Spain
⁴ Institute of Theoretical and Experimental Physics, 117259, Moscow, Russia

^* e-mail: konrad.tywoniuk@fys.uio.no

Received: 12 September 2008
Revised: 5 December 2008
Published online: 13 February 2009

Abstract

One observes strong suppression effects for hard probes, e.g. the production of J/ψ or high-p _T particles, in nucleus–nucleus (AA) collisions at RHIC. Surprisingly, the magnitude of the suppression is quite similar to that at SPS. In order to establish whether these features arise due to the presence of a thermalized system of quarks and gluons formed in the course of the collision, one should investigate the impact of suppression mechanisms which do not explicitly involve such a state. We calculate shadowing for gluons in the Glauber–Gribov theory and propose a model invoking a rapidity-dependent absorptive mechanism motivated by energy-momentum conservation effects. Furthermore, final-state suppression due to interaction with comoving matter (hadronic or pre-hadronic) has been shown to describe the data at SPS. We extend this model by including the backward reaction channel, i.e. recombination of open charm, which is estimated directly from pp data at RHIC. Strong suppression of charmonium both in pA and AA collisions at LHC is predicted. This is in stark contrast with the predictions of models assuming QGP formation and thermalization of heavy quarks.