358 research outputs found
Strangeness enhancement and Energy dependence in Heavy Ion Collisions
The canonical statistical model analysis of strange and multistrange hadron
production in central A-A relative to p-p/p-A collisions is presented over the
energy range from GeV up to GeV. It is shown that
the relative enhancement of strange particle yields from p-p/p-A to A-A
collisions substantially increases with decreasing collision energy. It is
largest at GeV, where the enhancement of and
is of the order of 100, 20 and 3, respectively. In terms of the model
these results are due to the canonical suppression of particle thermal phase
space at lower energies, which increases with the strangeness content of the
particle and with decreasing size of the collision fireball. The comparison of
the model with existing data on energy dependence of the kaon/pion ratio is
also discussed
Group projection method in statistical systems
We discuss an application of group theoretical methods to the formulation of
the thermodynamics of systems constrained by the conservation laws described by
a semi--simple compact Lie group. A general projection method that allows to
construct a partition function for a given irreducible representation of the
Lie group is outlined. Applications of the method in Lattice Gauge Theory (LGT)
for non--zero baryon number and in the phenomenological description of particle
production in ultrarelativistic heavy ion collisions are also indicated.Comment: Invited talk presented at the XXIV International Colloquium on Group
Theoritical Methods in Physic
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
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
enhancement at GeV.Comment: 4 pages, 4 figures. To appear in the proceedings of Quark Matter 2002
(Nantes, France
QGP formation and strange antibaryons
We analyze current experimental results and explore, as function of the collision energy and stopping in relativistic nuclear collisions, the production yields of strange antibaryons, assuming formation of a deconfined thermal QGP-fireball which undergoes a sudden hadronisation
Chemical equilibration of U(1) charged particles in a thermal environment
We discuss chemical equilibration of particles carrying non-vanishing quantum numbers related with U(1) internal symmetry. We construct the transport equation for the time evolution of particle multiplicities and their probability functions. The solution of these equations is obtained in different limiting cases. It is argued that a U(1) charged particles, dependent on thermal conditions inside a fireball, approaches different equilibrium limits. The differences between kinetics of abundantly and rarely produced particles are explained
Strangeness in Pb-Pb Collisions at 158 A GeV
We study relative strange particle abundances measured in Pb-Pb 158 A GeV interactions. The thermal and chemical source parameters of these particles are determined under reaction scenario hypothesis invoking confined and deconfined hadronic matter
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