Measurements of inclusive J/psi production in Pb-Pb collisions at sqrt(s_NN) = 2.76 TeV with the ALICE experiment

TL;DR

This paper reports measurements of inclusive J/psi production in Pb-Pb collisions at 2.76 TeV by the ALICE experiment, analyzing nuclear modification factors across different rapidities, centralities, and transverse momenta to understand QGP effects.

Contribution

It provides the first detailed measurement of J/psi suppression and regeneration effects at LHC energies, comparing results with theoretical models and other experiments.

Findings

J/psi suppression varies with centrality and rapidity.

Regeneration effects are significant at LHC energies.

Results are consistent with models including both suppression and regeneration mechanisms.

Abstract

Charmonium is a prominent probe of the Quark-Gluon Plasma (QGP), expected to be formed in ultrarelativistic heavy-ion (A-A) collisions. It has been predicted that the J/psi(c-cbar) particle is dissolved in the deconfined medium created in A-A systems. However this suppression can be counterbalanced via regeneration of the charm/anti-charm bound state in QGP or via statistical production at the phase boundary. At LHC energies, the latter mechanisms are expected to play a more important role, due to a charm production cross section significantly larger than at lower energies. Measurements obtained by the ALICE experiment for inclusive J/psi production are shown, making use of Pb-Pb data at sqrt(s_NN) = 2.76 TeV, collected in 2010 and 2011. In particular, the focus is given on the nuclear modification factor, R_AA, derived for forward (2.5 < y < 4) and mid rapidities (|y| < 0.9), both down to zero transverse momentum (pT). The centrality, y and pT dependences of R_AA are presented and discussed in the context of theoretical models, together with PHENIX and CMS results.