1,381 research outputs found
Baryon stopping and hyperon enhancement in the improved dual parton model
We present an improved version of the dual parton model which contains a new
realization of the diquark breaking mechanism of baryon stopping. We reproduce
in this way the net baryon yield in nuclear collisions. The model, which also
considers strings originating from diquark-antidiquark pairs in the nucleon
sea, reproduces the observed yields of p and Lambda and their antiparticles and
underestimates cascades by less than 50 %. However, Omega's are underestimated
by a factor five. Agreement with data is restored by final state interaction,
with an averaged cross-section as small as 0.14 mb. Hyperon yields increase
significantly faster than antihyperons, in agreement with experiment.Comment: 40 pages, 18 postscript figure
Nuclear Structure Functions at Small x from Inelastic Shadowing and Diffraction
Nuclear structure functions at small x and small or moderate are
studied using the relation with diffraction on nucleons which arises from
Gribov's Reggeon Calculus. A reasonable description of experimental data is
obtained with no fitted parameters. A comparison with other models and
predictions for future lepton-ion colliders are provided. Consequences for the
reduction of multiplicities in nucleus-nucleus collisions at energies of RHIC
and LHC are examined.Comment: LaTeX, 32 pages, 14 eps figures included using epsfig; 1 reference
update
Anomalous suppression of production at large transverse momentum in Au + Au and d + Au collisions at 200 GeV
We propose a model of suppression of large -pions in heavy ion
collisions based on the interaction of the large pion with the dense
medium created in the collision. The model is practically the same as the one
previously introduced to describe suppression. Both the and the
centrality dependence of the data are reproduced. In deuteron-gold collisions,
the effect of the final state interaction with the dense medium turns out to be
negligibly small. Here the main features of the data are also reproduced both
at mid and at forward rapidities.Comment: 20 pages, latex, 3 postscript figures. Last version, to be published
in EJP
Baryon Number Transfer in Hadronic Interaction
The process of baryon number transfer due to string junction propagation in
rapidity is considered. It has a significant effect in the net baryon
production in collisions at mid-rapidities and an even larger effect in
the forward hemisphere in the cases of and interactions. The
results of numerical calculations in the framework of the Quark-Gluon String
model are in reasonable agreement with the data.Comment: Latex, 17 figs. in ps files, 1 table. Submitted to EPJ C The title of
paper were changed, some proovings in the text, references and in figs were
mad
Nuclear Shadowing and Diffraction
The relation between diffraction in lepton-proton collisions and shadowing of
nuclear structure functions which arises from Gribov inelastic shadowing, is
described. A model realizing such relation, which produces a parameter-free
description of experimental data on nuclear structure functions at small ,
is presented. The application to the description of multiplicities in nuclear
collisions is discussed and related to other approaches.Comment: LaTeX, 6 pages, 5 eps figures, uses enclosed ws-ijmpa.cls; invited
talk given by N. Armesto at the Eighth Workshop on Non-Perturbative Quantum
Chromodynamics, Paris, France, June 7th-11th 200
Energy Dependence of Short and Long-Range Multiplicity Correlations in Au+Au Collisions from STAR
A general overview of the measurement of long-range multiplicity correlations
measured by the STAR experiment in Au+Au collisions at RHIC is presented. The
presence of long-range correlations can provide insight into the early stages,
and the type of matter produced in, these collisions. These measurements have
been made in Au+Au collisions at = 200 and 62.4 GeV. These
results indicate a relatively large long-range correlation is produced in Au+Au
collisions compared to a {\it pp} baseline at = 200 GeV. A
weaker long-range correlation is seen as a function of incident energy.
Further, comparison of the onset of the long-range correlation to the
calculated percolation density parameter at = 200 GeV is
presented.Comment: 8 pages, 6 figures, Conference Proceedings for the XI International
Workshop on Correlation and Fluctuation in Multiparticle Production,
Hangzhou, China, November 21-25, 200
Fluctuations and Correlations in STAR
The study of correlations and fluctuations can provide evidence for the
production of the quark-gluon plasma (QGP) in relativistic heavy ion
collisions. Various theories predict that the production of a QGP phase in
relativistic heavy ion collisions could produce significant event-by-event
correlations and fluctuations in, transverse momentum, multiplicity, etc. Some
of the recent results using STAR at RHIC will be presented along with results
from other experiments at RHIC. The focus is on forward-backward multiplicity
correlations, balance function, charge and transverse momentum fluctuations,
and correlations.Comment: 6 pages, 13 figures, Invited talk at QNP06, Madrid, Spain,June 200
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