1,090 research outputs found
Particle Number Fluctuations in Statistical Model with Exact Charge Conservation Laws
Even though the first momenta i.e. the ensemble average quantities in
canonical ensemble (CE) give the grand canonical (GC) results in large
multiplicity limit, the fluctuations involving second moments do not respect
this asymptotic behaviour. Instead, the asymptotics are strikingly different,
giving a new handle in study of statistical particle number fluctuations in
relativistic nuclear reactions. Here we study the analytical large volume
asymptotics to general case of multispecies hadron gas carrying fixed baryon
number, strangeness and electric charge. By means of Monte Carlo simulations we
have also studied the general multiplicity probability distributions taking
into account the decay chains of resonance states.Comment: 4 pages, 2 figures. The report of the talk given in Strangeness in
Quark Matter 2004, Cape Town. Submitted to J. Phys. G: Nucl. Part. Phy
Strangeness counting in high energy collisions
The estimates of overall strange quark production in high energy e+e-, pp and
ppbar collisions by using the statistical-thermal model of hadronisation are
presented and compared with previous works. The parametrization of strangeness
suppression within the model is discussed. Interesting regularities emerge in
the strange/non-strange produced quark ratio which turns out to be fairly
constant in elementary collisions while it is twice as large in SPS heavy ion
collision.Comment: talk given at Strangeness in Quark Matter 98, submitted to J. Phys.
Crossover transition in bag-like models
We formulate a simple model for a gas of extended hadrons at zero chemical
potential by taking inspiration from the compressible bag model. We show that a
crossover transition qualitatively similar to lattice QCD can be reproduced by
such a system by including some appropriate additional dynamics. Under certain
conditions, at high temperature, the system consist of a finite number of
infinitely extended bags, which occupy the entire space. In this situation the
system behaves as an ideal gas of quarks and gluons.Comment: Corresponds to the published version. Added few references and
changed the titl
Xi and AntiXi production in Pb+Pb collisions at 40 AGeV at CERN SPS
First results on the production of Xi and AntiXi hyperons in Pb+Pb
interactions at 40 AGeV are presented. The AntiXi/Xi ratio at midrapidity is
studied as a function of collision centrality. The ratio shows no significant
centrality dependence within statistical errors; it ranges from 0.07 to 0.15.
The AntiXi/Xi ratio for central Pb+Pb collisions increases strongly with the
collision energy.Comment: 6 pages, 6 figures, proceedings of SQM03, to be published in Journal
of Physics G; V2: changes in table 1 and figure
What is the meaning of the statistical hadronization model?
The statistical model of hadronization succeeds in reproducing particle
abundances and transverse momentum spectra in high energy collisions of
elementary particles as well as of heavy ions. Despite its apparent success,
the interpretation of these results is controversial and the validity of the
approach very often questioned. In this paper, we would like to summarize the
whole issue by first outlining a basic formulation of the model and then
comment on the main criticisms and different kinds of interpretations, with
special emphasis on the so-called "phase space dominance". While the ultimate
answer to the question why the statistical model works should certainly be
pursued, we stress that it is a priority to confirm or disprove the fundamental
scheme of the statistical model by performing some detailed tests on the rates
of exclusive channels at lower energy.Comment: 14 pages, to be published in the Proceedings of the International
workshop "Focus on multiplicity", Bari (Italy) June 17-19 200
Conditions for Confinement and Freeze-Out
Matter implies the existence of a large-scale connected cluster of a uniform
nature. The appearance of such clusters as function of hadron density is
specified by percolation theory. We can therefore formulate the freeze-out of
interacting hadronic matter in terms of the percolation of hadronic clusters.
The resulting freeze-out condition as function of temperature and
baryo-chemical potential interpolates between resonance gas behaviour at low
baryon density and repulsive nucleonic matter at low temperature, and it agrees
well with data.Comment: 9 pages, 5 figure
System Size Dependence of Particle Production at the SPS
Recent results on the system size dependence of net-baryon and hyperon
production as measured at the CERN SPS are discussed. The observed Npart
dependences of yields, but also of dynamical properties, such as average
transverse momenta, can be described in the context of the core corona
approach. Other observables, such as antiproton yields and net-protons at
forward rapidities, do not follow the predictions of this model. Possible
implications for a search for a critical point in the QCD phase diagram are
discussed. Event-by-event fluctuations of the relative core to corona source
contributions might influence fluctuation observables (e.g. multiplicity
fluctuations). The magnitude of this effect is investigated.Comment: 10 pages, 4 figurs. Proceedings of the 6th International Workshop on
Critical Point and Onset of Deconfinement in Dubna, Aug. 201
Multiplicity Distributions in Canonical and Microcanonical Statistical Ensembles
The aim of this paper is to introduce a new technique for calculation of
observables, in particular multiplicity distributions, in various statistical
ensembles at finite volume. The method is based on Fourier analysis of the
grand canonical partition function. Taylor expansion of the generating function
is used to separate contributions to the partition function in their power in
volume. We employ Laplace's asymptotic expansion to show that any equilibrium
distribution of multiplicity, charge, energy, etc. tends to a multivariate
normal distribution in the thermodynamic limit. Gram-Charlier expansion allows
additionally for calculation of finite volume corrections. Analytical formulas
are presented for inclusion of resonance decay and finite acceptance effects
directly into the system partition function. This paper consolidates and
extends previously published results of current investigation into properties
of statistical ensembles.Comment: 53 pages, 7 figure
The QCD confinement transition: hadron formation
We review the foundations and the applications of the statistical and the
quark recombination model as hadronization models.Comment: 45 pages, 16 figures, accepted for publication in Landolt-Boernstein
Volume 1-23
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