Quark Matter 2014 - XXIV International Conference on Ultrarelativistic Nucleus-Nucleus Collisions

Low-pT J/ψ in Pb-Pb collisions at forward rapidity with ALICE at the LHC

20 May 2014, 16:30

2h

spectrum (darmstadtium)

Board: F-32

Poster Open Heavy Flavour and Quarkonia Poster session

Speaker

Laure Marie Massacrier (Laboratoire de Physique Subatomique et des Technologies Associe)

Description

The aim of ultra-relativistic heavy-ion collisions is the study of nuclear matter at high temperature and pressure where quantum chromodynamics predicts the existence of a deconfined state of nuclear matter, the Quark-Gluon Plasma (QGP). Heavy quarks are expected to be produced in the initial partonic scatterings and interact with the deconfined medium making them ideal probes of the QGP. According to the color-screening model, quarkonium states are suppressed in the medium with different dissociation probabilities for the various states. Recent results from the ALICE collaboration on the measurement of the nuclear modification factor and elliptic flow of inclusive J/$\psi$ indicate that a significant fraction of the observed J/$\psi$ is produced via the recombination of charm quarks from the QGP phase. Quarkonium detection at forward rapidity is performed with the ALICE muon spectrometer in the range -4 $<\eta <$ -2.5 down to $p_{\mathrm{T}}$ = 0. We report on the first measurement of a low-$p_{\mathrm{T}}$ J/$\psi$ yield excess ($p_{\mathrm{T}}<$ 300 MeV/$c$) in Pb-Pb collisions at the LHC, in the centrality bins 50-70$\mathrm{\%}$ and 70-90$\mathrm{\%}$. Photoproduction of J/$\psi$ (occuring at $b<2R$) is proposed as the underlying physics mechanism. Such a mechanism may represent a promising signature to probe the charmonium color-screening dissociation in the QGP at LHC energies. In this poster, we will present two methods to quantify the J/$\psi$ low-$p_{\mathrm{T}}$ yield excess and we will give the status and perspectives of this analysis.

Presentation materials

Poster

posterQM_save_v2.pdf