1,629 research outputs found
Strangeness production in a constituent quark model
We develop a model to calculate strangeness production in both elementary and
heavy ion collisions, within the framework of a statistical approach to
hadronisation. Calculations are based on the canonical partition function of
the thermal Nambu-Jona-Lasinio model with exact conservation of flavor and
color. It turns out that the growth of strange quarks production in heavy ion
collisions is due to the initial excess of non-strange matter over antimatter,
whereas a suppression occurs for elementary collisions, owing to the constraint
of exact quantum charges conservation over small volumes.Comment: 7 pages, 3 figures, Proceedings of the GISELDA Meeting held in
Frascati, 14-18 January 200
Strangeness production in a statistical effective model of hadronisation
We suppose that overall strangeness production in both high energy elementary
and heavy ion collisions can be described within the framework of an
equilibrium statistical model in which the effective degrees of freedom are
constituent quarks as used in effective lagrangian models. In this picture, the
excess of relative strangeness production in heavy ion collisions with respect
to elementary particle collisions arises from the unbalance between initial
non-strange matter and antimatter and from the exact colour and flavour quantum
number conservation over different finite volumes. The comparison with the data
and the possible sources of model dependence are discussed.Comment: 7 pages, 2 .eps figures. Talk given at QCD@work, MartinaFranca
(Italy) June 16-20 2001, to be published in the Proceeding
A Monte-Carlo generator for statistical hadronization in high energy e+e- collisions
We present a Monte-Carlo implementation of the Statistical Hadronization
Model in e+e- collisions. The physical scheme is based on the statistical
hadronization of massive clusters produced by the event generator Herwig within
the microcanonical ensemble. We present a preliminary comparison of several
observables with measurements in e+e- collisions at the Z peak. Although a fine
tuning of the model parameters is not carried out, a general good agreement
between its predictions and data is found.Comment: 19 pages, 28 figures, 6 tables. v2: added sections on comparison
between the Statistical Hadronization Model and the Cluster Model and on the
interplay between Herwig cluster splitting algorithm and Statistical
Hadronization Model predictions. Fixed typos and references added. Version
accepted for publication in EPJ
Transverse momentum spectra of identified particles in high energy collisions with statistical hadronisation model
A detailed analysis is performed of transverse momentum spectra of several
identified hadrons in high energy collisions within the framework of the
statistical model of hadronisation. The effect of the decay chain following
hadron generation is accurately taken into account. The considered
centre-of-mass energies range from ~ 10 to 30 GeV in hadronic collisions (pi+
p, pp and Kp) and from ~ 15 to 45 GeV in e+e- collisions. A clear consistency
is found between the temperature parameter extracted from the present analysis
and that obtained from fits to average hadron multiplicities in the same
collision systems. This finding indicates that in the hadronisation, the
production of different particle species and their momentum spectra are two
closely related phenomenons governed by one parameter.Comment: Talk given by F. Becattini in "Correlations and Fluctuations 2000",
12 pp., 11 figure
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.
Strange quark production in a statistical effective model
An effective model with constituent quarks as fundamental degrees of freedom
is used to predict the relative strangeness production pattern in both high
energy elementary and heavy ion collisions. The basic picture is that of the
statistical hadronization model, with hadronizing color-singlet clusters
assumed to be at full chemical equilibrium at constituent quark level. Thus, by
assuming that at least the ratio between strange and non-strange constituent
quarks survives in the final hadrons, the apparent undersaturation of strange
particle phase space observed in the data can be accounted for. In this
framework, the enhancement of relative strangeness production in heavy ion
collisions in comparison with elementary collisions is mainly owing to the
excess of initial non-strange matter over antimatter and the so-called
canonical suppression, namely the constraint of exact color and flavor
conservation over small volumes.Comment: 22 pages, 9 postscript figures, slightly shortened version published
in Phys. Rev.
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
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
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