Orateur
M.
Christopher Powell
(Lawrence Berkeley National Laboratory)
Description
The production of quarkonium has been studied to provide information
about the hypothesized Quark Gluon Plasma (QGP) that is expected to be
created in relativistic heavy ion collisions at RHIC. Lattice QCD
predicts a suppression of quarkonium production in the presence of a hot
and dense medium relative to proton-proton collisions, with the
suppression pattern of the various quarkonium states providing insight
into the thermodynamic properties of the QGP. The suppression is
expected due to the Debye screening of the potential between heavy
quarks in a dense medium. However there are other effects due to the
presence of a QGP which may contribute to the modification of heavy
quark production, such as statistical coalescence of heavy
quark-antiquark pairs, or co-mover absorption. There are also ordinary
Cold Nuclear Matter (CNM) effects, such as the modification of nuclear
PDFs (shadowing), and final state nuclear absorption, which need to be
taken into account in order to fully quantify an anomalous suppression.
This can be achieved by studying the production of various quarkonium
states in p+p, d+A and A+A collisions. Furthermore, p+p collisions can
offer insight to the quarkonium production mechanism and feed down
effects from higher states.\\
In this talk we will report the results on heavy quarkonium production
in p+p, d+Au, and Au+Au collisions at midrapidity via the dielectron
decay channel at $\sqrt{s_{NN}} = 200$ GeV from STAR. Results from
J/$\psi$ production in p+p collisions will be presented to provide a
baseline for production and understand the quarkonium production
mechanism. The nuclear modification factor for J/$\psi$ will also be
reported, along with results from Upsilon production in p+p, d+Au, and
Au+Au collisions, to investigate the suppression of quarkonium at STAR.
Auteur principal
M.
Christopher Powell
(Lawrence Berkeley National Laboratory)
