592 research outputs found
An analysis of elastic scattering reactions with a Fermi-Dirac pomeron opaqueness in impact parameter space
In the Bourrely-Soffer-Wu model (BSW) we introduce for the pomeron a new
opaqueness in impact parameter space in terms of different quark contributions
described by a Fermi-Dirac distribution. In order to check the validity of this
assumption we consider , , and elastic scattering.
We emphasize the role of the gluon above the diffraction peak in the
differential cross sections. Once these contributions are determined we extend
the model to light nuclei elastic reactions like , p~^4\mbox{He} and
\pi^{\pm}~^4\mbox{He}. The results obtained show a good description of all
these elastic processes over the available experimental energy range and
moderate momentum transfer.Comment: 29 pages 25 figure
Determination of the forward slope in and elastic scattering up to LHC energy
In the analysis of experimental data on (or ) elastic
differential cross section it is customary to define an average forward slope
in the form , where is the momentum transfer. Taking as
working example the results of experiments at Tevatron and SPS, we will show
with the help of the impact picture approach, that this simplifying assumption
hides interesting information on the complex non-flip scattering amplitude, and
that the slope is not a constant. We investigate the variation of this
slope parameter, including a model-independent way to extract this information
from an accurate measurement of the elastic differential cross section. An
extension of our results to the LHC energy domain is presented in view of
future experiments.Comment: 12 pages, 6 figures, to appear in EPJ
The statistical parton distributions: status and prospects
New experimental results on polarized structure functions, cross sections for
neutral and charge current reactions and () charge
current on isoscalar targets are compared with predictions using the
statistical parton distributions, which were previously determined. New data on
cross sections for Drell-Yan processes, single jet in collisions and
inclusive production in collisions are also compared with
predictions from this theoretical approach. The good agreement which we find
with all these tests against experiment, strenghtens our opinion on the
relevance of the role of quantum statistics for parton distributions. We will
also discuss the prospects of this physical framework.Comment: 34 pages, 23 figures, references and figures adde
Statistical description of the proton spin with a large gluon helicity distribution
The quantum statistical parton distributions approach proposed more than one
decade ago is revisited by considering a larger set of recent and accurate Deep
Inelastic Scattering (DIS) experimental results. It enables us to improve the
description of the data by means of a new determination of the parton
distributions. We will see that a large gluon polarization emerges, giving a
significant contribution to the proton spin.Comment: 11 pages, 4 figure
New Statistical PDFs: Predictions and Tests up to LHC Energies
The quantum statistical parton distributions approach proposed more than one
decade ago is revisited by considering a larger set of recent and accurate Deep
Inelastic Scattering experimental results. It enables us to improve the
description of the data by means of a new determination of the parton
distributions. This global next-to-leading order QCD analysis leads to a good
description of several structure functions, involving unpolarized parton
distributions and helicity distributions, in a broad range of and and
in terms of a rather small number of free parameters. There are several
challenging issues, in particular the behavior of at
large , a possible large positive gluon helicity distribution, etc.. The
predictions of this theoretical approach will be tested for single-jet
production and charge asymmetry in production in and
collisions up to LHC energies, using recent data and also for forthcoming
experimental results.Comment: 4 pages, 3 figures, Invited talk at Diffraction 2016, Acireale,
Sicily (Italy), Sept. 2 - 8 (2016), to be published in the AIP Conference
Proceedings. arXiv admin note: substantial text overlap with arXiv:1510.0618
Nuclear EMC Effect in a Statistical Model
A simple statistical model in terms of light-front kinematic variables is
used to explain the nuclear EMC effect in the range , which
was constructed by us previously to calculate the parton distribution functions
(PDFs) of the nucleon. Here, we treat the temperature as a parameter of the
atomic number , and get reasonable results in agreement with the
experimental data. Our results show that the larger , the lower thus the
bigger volume , and these features are consistent with other models.
Moreover, we give the predictions of the quark distribution ratios,
\emph{i.e.}, , , and , and also the gluon ratio for iron as an example. The
predictions are different from those by other models, thus experiments aiming
at measuring the parton ratios of antiquarks, strange quarks, and gluons can
provide a discrimination of different models.Comment: 26 latex pages, 3 figure
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