Charmonia enhancement in quark-gluon plasma with improved description of c-quarks phase-distribution

We present a dynamical model of heavy quark evolution in the quark-gluon plasma (QGP) based on the Fokker-Planck equation. We then apply this model to the case of central ultra-relativistic nucleus-nucleus collisions performed at RHIC and estimate the component of $J/\psi$ production (integrated and differential) stemming from c-$\bar{c}$ pairs that are initially uncorrelated.Comment: contribution presented at SQM0

Tomography of the Quark Gluon Plasma by Heavy Quarks

Using the recently published model \cite{Gossiaux:2008jv,goss2} for the collisional energy loss of heavy quarks in a Quark Gluon Plasma (QGP), based on perturbative QCD (pQCD), we study the centrality dependence of $R_{AA}$ and $R_{AA}(p_T^{min})$, %= \frac{dN_{AA}/dp_T}{ dN_{pp}/dp_T}$ measured by the Phenix collaboration, and compare our model with other approaches based on pQCD and on Anti de Sitter/ Conformal Field Theory (AdS/CFT)Comment: proceedings for SQM0

Energy and system size dependence of \phi meson production in Cu+Cu and Au+Au collisions

We study the beam-energy and system-size dependence of \phi meson production (using the hadronic decay mode \phi -- K+K-) by comparing the new results from Cu+Cu collisions and previously reported Au+Au collisions at \sqrt{s_NN} = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented are from mid-rapidity (|y|<0.5) for 0.4 < pT < 5 GeV/c. At a given beam energy, the transverse momentum distributions for \phi mesons are observed to be similar in yield and shape for Cu+Cu and Au+Au colliding systems with similar average numbers of participating nucleons. The \phi meson yields in nucleus-nucleus collisions, normalised by the average number of participating nucleons, are found to be enhanced relative to those from p+p collisions with a different trend compared to strange baryons. The enhancement for \phi mesons is observed to be higher at \sqrt{s_NN} = 200 GeV compared to 62.4 GeV. These observations for the produced \phi(s\bar{s}) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.Comment: 20 pages and 5 figure