3,926 research outputs found
Probability distributions in statistical ensembles with conserved charges
The probability distributions for charged particle numbers and their
densities are derived in statistical ensembles with conservation laws. It is
shown that if this limit is properly taken then the canonical and grand
canonical ensembles are equivalent. This equivalence is proven on the most
general, probability distribution level.Comment: 5 pages. A little bit shorter version due to some editorial and
language changes. To be published in Phys. Rev.
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 ( A GeV), SPS/CERN ( A GeV) up to AGS/BNL ( A GeV) and SIS/GSI ( 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
Statistical Model and the mesonic-baryonic transition region
The statistical model assuming chemical equilibriumand local strangeness
conservation describes most of the observed features of strange particle
production from SIS up to RHIC. Deviations are found as the maximum in the
measured K+/pi+ ratio is much sharper than in the model calculations. At the
incident energy of the maximum, the statistical model shows that freeze out
changes regime from one being dominated by baryons at the lower energies toward
one being dominated by mesons. It will be shown how deviations from the usual
freeze-out curve influence the various particle ratios. Furthermore, other
observables exhibit also changes just in this energy regime.Comment: 9 pages, 7 figures, CPOD conference proceeding
Conservation Laws and Particle Production in Heavy Ion Collisions
We discuss the role of the conservation laws related with U(1) internal
symmetry group in the statistical model description of particle productions in
ultrarelativistic heavy ion collisions. We derive and show the differences in
particle multiplicities in the canonical and the grand canonical formulation of
quantum number conservation. The time evolution and the approach to chemical
equilibrium in the above ensembles is discussed in terms of kinetic master
equation. The application of the statistical model to the description of
(multi)strange particle yields at GSI/SIS and the SPS energies is also
presented.Comment: Invited talk at International Symposium on Hadron and Nuclei, Seoul,
Korea, 20-22 Feb 200
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/
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/ mesons at the phase
boundary.Comment: 4 pages, 3 figures, proceedings of QM201
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