6,253 research outputs found
Diffraction for non-believers
Diffractive reactions involving a hard scale can be understood in terms of
quarks and gluons. These reactions have become a valuable tool for
investigating the low-x structure of the proton and the behavior of QCD in the
high-density regime, and they may provide a clean environment to study or even
discover the Higgs boson at the LHC. In this paper we give a brief introduction
to the description of diffraction in QCD. We focus on key features studied in
ep collisions at HERA and outline challenges for understanding diffractive
interactions at the LHC.Comment: 23 pages, 26 figures. Contributed to the Proceedings of the Workshop
on HERA and the LHC, DESY and CERN, 2004-200
A Spectrometer to Study Elastic and Diffractive Physics at LHC
The possibility to study elastic and diffractive physics in pp collisions at
LHC is investigated. For this purpose we have considered detectors close to the
beam in conjunction with the magnetic elements of the accelerator to provide a
high precision spectrometer for very forward final state protons. The
geometrical acceptance is given and momentum resolution is calculated for
different spatial resolution detectors.Comment: 26 pages, 13 figures, Latex, submitted in International Journal of
Modern Physics
Effect due to charge symmetry violation on the Paschos-Wolfenstein relation
The modification of the Paschos-Wolfenstein relation is investigated when the
charge symmetry violations of valence and sea quark distributions in the
nucleon are taken into account. We also study qualitatively the impact of
charge symmetry violation (CSV) effect on the extraction of
from deep inelastic neutrino- and antineutrino-nuclei
scattering within the light-cone meson-baryon fluctuation model. We find that
the effect of CSV is too small to give a sizable contribution to the NuTeV
result with various choices of mass difference inputs, which is consistence
with the prediction that the strange-antistrange asymmetry can account for
largely the NuTeV deviation in this model. It is noticeable that the effect of
CSV might contribute to the NuTeV deviation when the larger difference between
the internal momentum scales, of the proton and of
the neutron, is considered.Comment: 15 Latex pages, no figure, final version to appear in PR
Nuclear parton distributions at next to leading order
We perform a next to leading order QCD global analysis of nuclear deep
inelastic scattering and Drell-Yan data using the convolution approach to
parameterize nuclear parton densities. We find both a significant improvement
in the agreement with data compared to previous extractions, and substantial
differences in the scale dependence of nuclear effects compared to leading
order analyses.Comment: 9 pages, 10 figure
DIPSI: a Monte Carlo generator for elastic vector meson production in charged lepton-proton scattering
We present a Monte Carlo generator for exclusive vector meson production in
charged lepton-proton interactions, l+p --> l+p+V, based on a QCD leading
logarithm model calculation according to which the cross section for this
process is proportional to the square of the gluon momentum density in the
proton. The generator can be used for both fixed target and collider
kinematics. Each event is assigned a weight equal to its cross section, so that
the independent variables can be generated according to convenient
distributions, not necessarily identical to the physics ones.Comment: 24 pages, 7 figures, Latex, to be published in Computer Physics
Communication
Resummed QCD Power Corrections to Nuclear Shadowing
We calculate and resum a perturbative expansion of nuclear enhanced power
corrections to the structure functions measured in deeply inelastic scattering
of leptons on a nuclear target. Our results for the Bjorken -, - and
-dependence of nuclear shadowing in and the nuclear
modifications to , obtained in terms of the QCD factorization
approach, are consistent with the existing data. We demonstrate that the
low- behavior of these data and the measured large longitudinal structure
function point to a critical role for the power corrections when compared to
other theoretical approaches.Comment: 4 pages, 3 figures, uses RevTeX 4. As published in Phys.Rev.Let
Color Transparency via Coherent Exclusive rho Production
We examine the potential of the COMPASS experiment at CERN to study color
transparency via exclusive coherent vector meson production in hard
muon-nucleus scattering. It is demonstrated that COMPASS has high sensitivity
to test this important prediction of perturbative QCD.Comment: Feasibility study for COMPASS collaboration, 3 pages, no figures, 1
table. This contribution is based on talk presented at the Workshop on Spin
Physics, Trento, Italy, July 2001. The conference www site is
http://ECTstar.ect.it/contents.html The proceedings of the workshop will be
published as a special issue of Nuclear Physics B (proc suppl), eds. S Bass,
A De Roeck and A Deshpande. A more complete 26 page feasibility study with 7
figures and 3 tables is available as A. Sandacz et al., hep-ex/0106076
Revision of 26 Sept. for Ref. 11 modificatio
A Prototype Model of Stock Exchange
A prototype model of stock market is introduced and studied numerically. In
this self-organized system, we consider only the interaction among traders
without external influences. Agents trade according to their own strategy, to
accumulate his assets by speculating on the price's fluctuations which are
produced by themselves. The model reproduced rather realistic price histories
whose statistical properties are also similar to those observed in real
markets.Comment: LaTex, 4 pages, 4 Encapsulated Postscript figures, uses psfi
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