Statistical hadronization of charm at SPS, RHIC and LHC

We study the production of charmonia and charmed hadrons for nucleus-nucleus collisions at SPS, RHIC, and LHC energies within the framework of the statistical hadronization model. Results from this model are compared to the observed centrality dependence of J/psi production at SPS energy. We further provide predictions for the centrality dependence of the production of open and hidden charm mesons at RHIC and LHC.Comment: Contribution to Quark Matter 2002, 4 pages, 3 figures; revised version including charmed hyperons (omitted in v1

Charmonium Production from the Secondary Collisions at LHC Energy

We consider the charmonium production in thermalized hadronic medium created in ultrarelativistic heavy ion collisions at LHC energy. The calculations for the secondary $J/\psi$ and $\psi^,$ production by $D\bar D$ annihilation are performed within a kinetic model taking into account the space-time evolution of a longitudinally and transversely expanding medium. We show that the secondary charmonium production appears almost entirely during the mixed phase and it is very sensitive to the charmonium dissociation cross section with co-moving hadrons. Within the most likely scenario for the dissociation cross section of the $J/\psi$ mesons their regeneration in the hadronic medium will be negligible. The secondary production of $\psi^,$ mesons however, due to their large cross section above the threshold, can substantially exceed the primary yield.Comment: ps file 11

Thermal description of hadron production in e+e- collisions revisited

We present a comprehensive analysis of hadron production in e+e- collisions at different center-of-mass energies in the framework of the statistical model of the hadron resonance gas. The model is formulated in the canonical ensemble with exact conservation of all relevant quantum numbers. The parameters of the underlying model were determined using a fit to the average multiplicities of the latest measurements at $\sqrt{s}$ = 10, 29-35, 91 and 130-200 GeV. The results demonstrate that, within the accuracy of the experiments, none of the data sets is satisfactorily described with this approach, calling into question the notion that particle production in e+e- collisions is thermal in origin.Comment: 13 pages, 3 figures; v2: final version accepted for publication in Phys. Lett.

Hadron production in Au-Au collisions at RHIC

We present an analysis of particle production yields measured in central Au-Au collisions at RHIC in the framework of the statistical thermal model. We demonstrate that the model extrapolated from previous analyses at SPS and AGS energy is in good agreement with the available experimental data at $\sqrt s=130$ GeV implying a high degree of chemical equilibration. Performing a $\chi^2$ fit to the data, the range of thermal parameters at chemical freezeout is determined. At present, the best agreement of the model and the data is obtained with the baryon chemical potential $\mu_B\simeq 46\pm 5$ MeV and temperature $T\simeq 174\pm 7$ MeV. More ratios, such as multistrange baryon to meson, would be required to further constrain the chemical freezeout conditions. Extrapolating thermal parameters to higher energy, the predictions of the model for particle production in Au-Au reactions at $\sqrt s=200$ GeV are also given.Comment: Final version, minor changes to text and figures. To appear in Phys. Lett.

Particle Production in Heavy Ion Collisions

The status of thermal model descriptions of particle production in heavy ion collisions is presented. We discuss the formulation of statistical models with different implementation of the conservation laws and indicate their applicability in heavy ion and elementary particle collisions. We analyze experimental data on hadronic abundances obtained in ultrarelativistic heavy ion collisions, in a very broad energy range starting from RHIC/BNL ($\sqrt s=200$ A GeV), SPS/CERN ($\sqrt s\simeq 20$ A GeV) up to AGS/BNL ($\sqrt s\simeq 5$ A GeV) and SIS/GSI ($\sqrt s\simeq 2$ A GeV) to test equilibration of the fireball created in the collision. We argue that the statistical approach provides a very satisfactory description of experimental data covering this wide energy range. Any deviations of the model predictions from the data are indicated. We discuss the unified description of particle chemical freeze--out and the excitation functions of different particle species. At SPS and RHIC energy the relation of freeze--out parameters with the QCD phase boundary is analyzed. Furthermore, the application of the extended statistical model to quantitative understanding of open and hidden charm hadron yields is considered.Comment: Invited review for Quark Gluon Plasma 3, eds. R. C. Hwa and Xin-Nian Wang, World Scientific Publishin

Charmonium and open charm production in nuclear collisions at SPS/FAIR energies and the possible influence of a hot hadronic medium

We provide predictions for charmonium and open charm production in nuclear collisions at SPS/FAIR energies within the framework of the statistical hadronization model. The increasing importance at lower energies of Lambda_c production is demonstrated and provides a challenge for future experiments. We also demonstrate that, because of the large charm quark mass and the different timescales for charm quark and charmed hadron production, possible modifications of charmed hadrons in the hot hadronic medium do not lead to measurable changes in cross sections for D-meson production. A possible influence of medium effects can be seen, however, in yields of charmonium. These effects are visible at all energies and results are presented for the energy range between charm threshold and RHIC energy.Comment: 12 pages, 4 figures; v2: slightly revised text and updated calculations; v3: slightly enhanced discussion, one more ref.; data file with calculations will be available at http://www-linux.gsi.de/~andronic/physics/charm

The statistical model in Pb-Pb collisions at the LHC

We briefly review the predictions of the thermal model for hadron production in comparison to latest data from RHIC and extrapolate the calculations to LHC energy. Our main emphasis is to confront the model predictions with the recently released data from ALICE at the LHC. This comparison reveals an apparent anomaly for protons and anti-protons which we discuss briefly. We also demonstrate that our statistical hadronization predictions for J/$\psi$ production agree very well with the most recent LHC data, lending support to the picture in which there is complete charmonium melting in the quark-gluon plasma (QGP) followed by statistical generation of J/$\psi$ mesons at the phase boundary.Comment: 4 pages, 3 figures, proceedings of QM201

Canonical aspects of strangeness enhancement

Strangeness enhancement (SE) in heavy ion collisions can be understood in the statistical model on the basis of canonical suppression. In this formulation,SE is a consequence of the transition from canonical to the asymptotic grand canonical limit and is predicted to be a decreasing function of collision energy. This model predictions are consistent with the recent NA49 data on $\Lambda$ enhancement at $p_{lab}=40, 80, 158$ GeV.Comment: 4 pages, 4 figures. To appear in the proceedings of Quark Matter 2002 (Nantes, France