880 research outputs found
Lessons from LHC elastic and diffractive data
We discuss a model which gives a `global' description of the wide variety of
high-energy elastic and diffractive data that are presently available,
particularly from the LHC experiments. The model is based on only one pomeron
pole, but includes multi-pomeron interactions. Significantly, the LHC
measurements require that the model includes the transverse momentum dependence
of the intermediate partons as a function of their rapidity, which results in a
rapidity (or energy) dependence of the multi-pomeron vertices.Comment: 9 pages, 2 figures, To be published in the Proceedings of the
International Workshop on Particle Physics Phenomenology in memory of Alexei
Kaidalov, Moscow, 21-25 July, 201
Coherent J/psi production - a novel feature at LHC?
Energy dependence of heavy quarkonia production in hadron-nucleus collisions
is studied in the framework of the Glauber-Gribov theory. We emphasize a change
in the space-time picture of heavy-quark state production on nuclei with
energy. Longitudinally ordered scattering of a heavy-quark system takes place
at low energies, while with increasing energy it transforms to a coherent
scattering of projectile partons on the nuclear target. The characteristic
energy scale for this transition depends on masses and rapidities of produced
particles. For J/psi, produced in the central rapidity region, the transition
happens at RHIC energies. The parameter-free calculation of J/psi in dAu
collisions is in good agreement with recent RHIC data. We use distributions of
gluons in nuclei to predict suppression of heavy quarkonia at LHC.Comment: 13 pages, 4 figures; experimental data and reference included,
conclusions unchanged; to appear in Phys. Lett.
Gluon shadowing in the Glauber-Gribov model at HERA
We calculate shadowing using new data on the gluon density of the Pomeron
recently measured with high precision at HERA. The calculations are made in a
Glauber-Gribov framework and Pomeron tree-diagrams are summed up within a
unitarity-conserving procedure. The total cross section of \vphot A
interaction is then found in a parameter-free description, employing gluon
diffractive and inclusive distribution functions as input. A strong shadowing
effect is obtained, in good agreement with several other models. Impact
parameter dependence of gluon shadowing is also presented.Comment: 18 pages, 6 figures; references added, discussion of model enlarged,
calculation of low-x contribution corrected; to appear in Phys. Let
Phenomenology of soft hadron interactions and the relevant EAS data
The interpretation of the experimental data in superhigh energy cosmic rays requires the calculations using various models of elementary hadron interaction. One should prefer the models justified by accelerator data and giving definite predictions for superhigh energies. The model of quark-gluon pomeron strings (the QGPS models) satisfies this requirement
Resolving the J/\psi RHIC puzzles at LHC
Experiments with gold-gold collisions at RHIC have revealed (i) stronger
suppression of charmonium production at forward rapidity than at midrapidity
and (ii) the similarity between the suppression degrees at RHIC and SPS
energies. To describe these findings we employ the model that includes nuclear
shadowing effects, calculated within the Glauber-Gribov theory,
rapidity-dependent absorptive mechanism, caused by energy-momentum
conservation, and dissociation and recombination of the charmonium due to
interaction with co-moving matter. The free parameters of the model are tuned
and fixed by comparison with experimental data at lower energies. A good
agreement with the RHIC results concerning the rapidity and centrality
distributions is obtained for both heavy Au+Au and light Cu+Cu colliding
system. For pA and A+A collisions at LHC the model predicts stronger
suppression of the charmonium and bottomonium yields in stark contrast to
thermal model predictions.Comment: SQM2008 proceedings, 6 page
Gluon shadowing in the Glauber-Gribov model
New data from HERA experiment on (diffractive) deep inelastic scattering has
been used to parameterize nucleon and Pomeron structure functions. Within the
Gribov theory, the parameterizations were employed to calculate gluon shadowing
for various heavy ions and compared our results with predictions from other
models. Calculations for d+Au collisions at forward rapidities at
ultra-relativistic energies have been made and are compared to RHIC data on the
nuclear modification factor. Results for gluon shadowing are also confronted
with recent data on the nuclear modification factor at GeV at
various values of the Feynman variable , and the energy dependence of the
effect is discussed.Comment: To appear in the proceedings of the Workshop for young scientists on
the physics of ultrarelativistic nucleus-nucleus collisions, Hot Quarks 2006.
To be published in EPJ
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
J/psi c\bar{c} production in e+e- and hadronic interactions
Predictions of the nonperturbative Quark Gluon Strings model based on the
1/N-expansion in QCD and string picture of interactions for production of
states containing heavy quarks are considered. Relations between fragmentation
functions for different states are used to predict the fragmentation function
of c-quark to J/psi-mesons. The resulting cross section for J/psi-production in
e+e- annihilation is in a good agreement with recent Belle result. It is argued
that associated production of c\bar{c} states with open charm should give a
substantial contribution to production of these states in hadronic interactions
at very high energies.Comment: 7 pages, 2 figure
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