103 research outputs found
The Interacting Gluon Model: a review
The Interacting Gluon Model (IGM) is a tool designed to study energy flow,
especially stopping and leading particle spectra, in high energy hadronic
collisions. In this model, valence quarks fly through and the gluon clouds of
the hadrons interact strongly both in the soft and in the semihard regime.
Developing this picture we arrive at a simple description of energy loss, given
in terms of few parameters, which accounts for a wide variety of experimental
data. This text is a survey of our main results and predictions.Comment: 22 pages, 21 figure
Hadronic form factors and the secondary production cross section: an update
Improving previous calculations, we compute the cross section using the most complete effective lagrangians available. The
new crucial ingredients are the form factors on the charm meson vertices, which
are determined from QCD sum rules calculations. Some of them became available
only very recently and the last one, needed for our present purpose, is
calculated in this work.Comment: 12 pages, 9 eps figure
Does the production asymmetry decrease at large ?
We have applied the meson cloud model (MCM) to calculate the asymmetries in
and meson production in high energy -nucleus and
-nucleus collisions. We find a good agreement with recent data. Our
results suggest that the asymmetries may decrease at large .Comment: revised version with new figures and added references to appear in
Phys. Rev. Let
Meson Cloud and SU(3) Symmetry Breaking in Parton Distributions
We apply the Meson Cloud Model to the calculation of nonsinglet parton
distributions in the nucleon sea, including the octet and the decuplet cloud
baryon contributions. We give special attention to the differences between
nonstrange and strange sea quarks, trying to identify possible sources of SU(3)
flavor breaking. A analysis in terms of the parameter is presented,
and we find that the existing SU(3) flavor asymmetry in the nucleon sea can be
quantitatively explained by the meson cloud. We also consider the
baryon, finding similar conclusions.Comment: 17 pages, LaTeX, 8 figures in .ps file
On the rapidity dependence of the average transverse momentum in hadronic collisions
The energy and rapidity dependence of the average transverse momentum
in and collisions at RHIC and LHC energies are
estimated using the Colour Glass Condensate (CGC) formalism. We update previous
predictions for the - spectra using the hybrid formalism of the CGC
approach and two phenomenological models for the dipole - target scattering
amplitude. We demonstrate that these models are able to describe the RHIC and
LHC data for the hadron production in , and collisions at GeV. Moreover, we present our predictions for and
demonstrate that the ratio decreases with the rapidity and has a behaviour similar to that
predicted by hydrodynamical calculations.Comment: 11 pages, 7 figures; revised version: new results for the average
transverse momentum at partonic level added in fig. 4; Results and Discussion
section has been improved and enlarge
Testing the running coupling -factorization formula for the inclusive gluon production
The inclusive gluon production at midrapidities is described in the Color
Glass Condensate formalism using the - factorization formula, which was
derived at fixed coupling constant considering the scattering of a dilute
system of partons with a dense one. Recent analysis demonstrated that this
approach provides a satisfactory description of the experimental data for the
inclusive hadron production in collisions. However, these studies
are based on the fixed coupling - factorization formula, which does not
take into account the running coupling corrections, which are important to set
the scales present in the cross section. In this paper we consider the running
coupling corrected - factorization formula conjectured some years ago and
investigate the impact of the running coupling corrections on the observables.
In particular, the pseudorapidity distributions and charged hadrons
multiplicity are calculated considering , and
collisions at RHIC and LHC energies. We compare the corrected running coupling
predictions with those obtained using the original - factorization
assuming a fixed coupling or a prescription for the inclusion of the running of
the coupling. Considering the Kharzeev - Levin - Nardi unintegrated gluon
distribution and a simplified model for the nuclear geometry, we demonstrate
that the distinct predictions are similar for the pseudorapidity distributions
in collisions and for the charged hadrons multiplicity in
collisions. On the other hand, the running coupling corrected -
factorization formula predicts a smoother energy dependence for in
collisions.Comment: 9 pages and 4 figure
Charm and longitudinal structure functions with the Kharzeev-Levin-Nardi model
We use the Kharzeev-Levin-Nardi model of the low gluon distributions to
fit recent HERA data on charm and longitudinal structure functions. Having
checked that this model gives a good description of the data, we use it to
predict and to be measured in a future electron-ion collider. The
results interpolate between those obtained with the de Florian-Sassot and
Eskola-Paukkunen-Salgado nuclear gluon distributions. The conclusion of this
exercise is that the KLN model, simple as it is, may still be used as an
auxiliary tool to make estimates both for heavy ion and electron-ion
collisions.Comment: 6 pages, 7 figure
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