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

TL;DR

This paper investigates the suppression of J/psi particles in heavy-ion collisions, proposing models that do not rely on quark-gluon plasma formation and predicting strong suppression at LHC energies.

Contribution

It introduces a model based on shadowing and energy-momentum conservation effects, including recombination, to explain J/psi suppression without assuming quark-gluon plasma formation.

Findings

Shadowing effects calculated using Glauber-Gribov theory.

Recombination of open charm estimated from pp data.

Predicted strong J/psi suppression at LHC.

Abstract

One observes strong suppression effects for hard probes, e.g. the production of J/psi or high-pT 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 co-moving matter (hadronic or pre-hadronic) has been shown to describe 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.