3,367 research outputs found
Statistical hadronization and hadronic microcanonical ensemble II
We present a Monte-Carlo calculation of the microcanonical ensemble of the of
the ideal hadron-resonance gas including all known states up to a mass of about
1.8 GeV and full quantum statistics. The microcanonical average multiplicities
of the various hadron species are found to converge to the canonical ones for
moderately low values of the total energy, around 8 GeV, thus bearing out
previous analyses of hadronic multiplicities in the canonical ensemble. The
main numerical computing method is an importance sampling Monte-Carlo algorithm
using the product of Poisson distributions to generate multi-hadronic channels.
It is shown that the use of this multi-Poisson distribution allows an efficient
and fast computation of averages, which can be further improved in the limit of
very large clusters. We have also studied the fitness of a previously proposed
computing method, based on the Metropolis Monte-Carlo algorithm, for event
generation in the statistical hadronization model. We find that the use of the
multi-Poisson distribution as proposal matrix dramatically improves the
computation performance. However, due to the correlation of subsequent samples,
this method proves to be generally less robust and effective than the
importance sampling method.Comment: 23 pages, 21 figures, style files attached. Published version, minor
correction
Statistical hadronization and hadronic microcanonical ensemble I
We present a full treatment of the microcanonical ensemble of the ideal
hadron-resonance gas in a quantum-mechanical framework which is appropriate for
the statistical model of hadronization. By using a suitable transition operator
for hadronization we are able to recover the results of the statistical theory,
particularly the expressions of the rates of different channels. Explicit
formulae are obtained for the phase space volume or density of states of the
ideal relativistic gas in quantum statistics which, for large volumes, turn to
a cluster decomposition whose terms beyond the leading one account for
Bose-Einstein and Fermi-Dirac correlations. The problem of the computation of
the microcanonical ensemble and its comparison with the canonical one, which
will be the main subject of a forthcoming paper, is addressed.Comment: 15 pages, LaTeX macros svjour.cls and svepj.clo needed, revised
version to be published in Eur. Phys. J.
Statistical hadronisation phenomenology
The analyses of hadron production in the framework of the statistical
hadronisation model are reviewed. The analysis of average multiplicities in
collisions at relatively low centre-of-mass energy confirms previous findings,
namely the universality of hadronisation temperature and of strange to
non-strange quark production rate. The study of transverse momentum spectra of
identified hadrons allows a further determination of the hadronisation
temperature which is found to be compatible with that obtained from fits to
average multiplicities.Comment: 5 pages, 4 .eps figures, talk given at Statistical QCD, Bielefeld,
August 2001, to appear in the proceeding
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
Polarization in relativistic heavy ion collisions: a theoretical perspective
We review the theoretical framework for the calculation of particle
polarization in relativistic heavy ion collisions within the hydrodynamical
model. The covariant decomposition of the mean spin vector is presented and
open theoretical issues addressed.Comment: 6 pages, talk given at Strangeness in Quark Matter conference,
Utrecht, July 10-15 201
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