40 research outputs found
Photoproduction constraints on J/psi-nucleon interactions
Using J/psi and open charm photoproduction data, we apply the vector meson
dominance model to obtain constraints on the energy dependence of the inelastic
J/psi-nucleon cross section. Predictions of short distance QCD are in accord
with these constraints, while recently proposed hadronic models for J/psi
dissociation strongly violate them.Comment: 9 pages, 5 figures, late
Non-extensivity Parameter of Thermodynamical Model of Hadronic Interactions at LHC energies
The LHC measurements above SPS and Tevatron energies give the opportunity to
test predictions of non-extensive thermodynamical picture of hadronic
interaction to examine measured transverse momenta distributions for new
interaction energy range. We determined Tsallis model non-extensivity parameter
for the hadronization process before short-lived particles decayed and distort
the initial p_t distribution. We have shown that it follows exactly smooth rise
determined at lower energies below present LHC record. The shape of the q
parameter energy dependence is consistent with expectations and the evidence of
the asymptotic limit may be seen.Comment: 2 pages, 2 figure
Predictions of hadron abundances in pp collisions at the LHC
Based on the statistical hadronization model, we obtain quantitative
predictions for the relative abundances of hadron species in pp collisions at
the LHC. By using the parameters of the model determined at sqrt s = 200 GeV,
and extrapolating the overall normalization from ppbar collisions at the SPS
and Tevatron, we find that the expected rapidity densities are almost
grand-canonical. Therefore, at LHC the ratios between different species become
essentially energy-independent, provided that the hadronization temperature T_H
and the strangeness suppression factor gamma_S retain the stable values
observed in the presently explored range of pp and ppbar collisions.Comment: 4 pages. Final version published in JP
Heavy quark(onium) at LHC: the statistical hadronization case
We discuss the production of charmonium in nuclear collisions within the
framework of the statistical hadronization model. We demonstrate that the model
reproduces very well the availble data at RHIC. We provide predictions for the
LHC energy where, dependently on the charm production cross section, a
dramatically different behaviour of charmonium production as a function of
centrality might be expected. We discuss also the case in elementary
collisions, where clearly the statistical model does not reproduce the
measurements.Comment: 8 pages, 5 figures; proceeding of SQM09, Buzios, Brazil, to be
published in J. Phys.
The thermal model on the verge of the ultimate test: particle production in Pb-Pb collisions at the LHC
We investigate the production of hadrons in nuclear collisions within the
framework of the thermal (or statistical hadronization) model. We discuss both
the ligh-quark hadrons as well as charmonium and provide predictions for the
LHC energy. Even as its exact magnitude is dependent on the charm production
cross section, not yet measured in Pb-Pb collisions, we can confidently predict
that at the LHC the nuclear modification factor of charmonium as a function of
centrality is larger than that observed at RHIC and compare the experimental
results to these predictions.Comment: 4 pages, 3 figures; proceedings of QM201
Statistical hadronization phenomenology in fluctuations at ultra-relativistic energies
We discuss the information that can be obtained from an analysis of
fluctuations in heavy ion collisions within the context of the statistical
model of particle production. We then examine the recently published
experimental data on ratio fluctuations, and use it to obtain constraints on
the statistical properties (physically relevant ensemble, degree of chemical
equilibration, scaling across energies and system sizes) and freeze-out
dynamics (amount of reinteraction between chemical and thermal freeze-out) of
the system.Comment: Proceedings, SQM2009. Fig. 4, the main results figure, was wrong due
to editing mistake, now correcte
Kinetic equation for gluons at the early stage
We derive the kinetic equation for pure gluon QCD plasma in a general way,
applying the background field method. We show that the quantum kinetic equation
contains a term as in the classical case, that describes a color charge
precession of partons moving in the gauge field. We emphasize that this new
term is necessary for the gauge covariance of the resulting equation.Comment: 6 pages, no figure, to appear in the proceedings of the 6th
international conference on strange quarks in matter, Frankfurt, Germany,
25-29 september 200
Open and Hidden Charm Production in Heavy Ion Collisions at Ultrarelativistic Energies
We consider the production of the open charm and J/psi mesons in heavy ion
collisions at BNL RHIC. We discuss several recently developed pictures for
J/psi production and argue that a measurement at RHIC energies is crucial for
disentangling these different descriptions.Comment: 19 pages, Latex, 5 PS-figures. v3: Fig.6 is adde
The Speed of Sound in Hadronic Matter
We calculate the speed of sound in an ideal gas of resonances whose
mass spectrum is assumed to have the Hagedorn form , which leads to singular behavior at the critical temperature
. With the pressure and the energy density remain finite at
, while the specific heat diverges there. As a function of the temperature
the corresponding speed of sound initially increases similarly to that of an
ideal pion gas until near where the resonance effects dominate causing
to vanish as . In order to compare this result to the
physical resonance gas models, we introduce an upper cut-off M in the resonance
mass integration. Although the truncated form still decreases somewhat in the
region around , the actual critical behavior in these models is no longer
present.Comment: 11 Pages, 9 Figures and 17 Reference