Speaker
Hugo Denis Antonio Pereira Da Costa
(CEA/IRFU,Centre d'etude de Saclay Gif-sur-Yvette (FR))
Description
Charmonia (for instance J/ψ and ψ(2S)) are mesons formed of a charm and anti-charm
quark pair. In high-energy hadronic collisions such as those delivered by the LHC between
2010 and 2013, charmonium production results from the hard scattering of two gluons,
which occurs very early. In heavy ion collisions, charmonia can thus probe all states of the
nuclear matter formed afterward and have therefore been used extensively to study the
properties of the Quark-Gluon Plasma (QGP).
In this presentation we will report on published charmonium measurements performed
by ALICE in Pb − Pb collisions at a center of mass energy per nucleon-nucleon collision
√sNN = 2.76 TeV, at both mid (|y| < 0.8) and forward (2.5 < y < 4) rapidities. The
nuclear modification factor of inclusive J/ψ will be presented as a function of the collision
centrality, the J/ψ transverse momentum (pT) as well as its rapidity. The variation of the
J/ψ mean transverse momentum and mean transverse momentum squared as a function
of the collision centrality will also be discussed. These measurements will be compared to
models that include one or several of the following mechanisms: color screening; balance
between dissociation and recombination in the QGP; recombination at the QGP phase
boundary; interaction with a dense comoving medium. Results on the production of the
heavier and less bound ψ(2S) meson in Pb − Pb collisions at forward-rapidity will also
be presented and compared to both models and measurements performed by other experiments. At mid-rapidity we will also report on ALICE unique capability to separate prompt
and non-prompt J/ψ production down to low pT (≥ 1.5 GeV/c) and thus provide direct
insight on the energy loss of b quarks in the QGP.
| On behalf of collaboration: | ALICE |
|---|
Author
Hugo Denis Antonio Pereira Da Costa
(CEA/IRFU,Centre d'etude de Saclay Gif-sur-Yvette (FR))
