10,391 research outputs found
Diffractive photoproduction of heavy quarks in hadronic collisions
In this letter we study the diffractive photoproduction of heavy quarks in
hadronic (pp/pA/AA) interactions for Tevatron and LHC energies. The integrated
cross section and rapidity distribution for the process h_1 h_2 --> h_1 h_2
QQBAR (h_i = p,A and Q = c,b) are estimated using the Color Glass Condensate
(CGC) formalism. Our results indicate that this production channel has larger
cross sections than the competing reactions of double diffractive production
and coherent AA reactions initiated by two-photon collisions.Comment: 4 pages, 2 figures, 1 table. Version to be published in Physical
Review
Longitudinal profiles of Extensive Air Showers with inclusion of charm and bottom particles
Charm and bottom particles are rare in Extensive Air Showers but the effect
of its presence can be radical in the development of the Extensive Air Showers
(EAS). If such particles arise with a large fraction of the primary energy,
they can reach large atmospheric depths, depositing its energy in deeper layers
of the atmosphere. As a consequence, the EAS observables (, and
) will be modified, as well as the shape of the longitudinal profile
of the energy deposited in the atmosphere. In this paper, we will modify the
CORSIKA Monte Carlo by the inclusion of charm and bottom production in the
first interaction of the primary cosmic ray. Results for different selections
of the typical values of the heavy particles and distinct production
models will be presented.Comment: Replacement of tex file by the correct versio
The AGL Equation from the Dipole Picture
The AGL equation includes all multiple pomeron exchanges in the double
logarithmic approximation (DLA) limit, leading to an unitarized gluon
distribution in the small x regime. This equation was originally obtained using
the Glauber-Mueller approach. We demonstrate in this paper that the AGL
equation and, consequently, the GLR equation, can also be obtained from the
dipole picture in the double logarithmic limit, using an evolution equation,
recently proposed, which includes all multiple pomeron exchanges in the leading
logarithmic approximation. Our conclusion is that the AGL equation is a good
candidate for an unitarized evolution equation at small x in the DLA limit.Comment: 16 pages, 2 figures. Accepted for publication in Nuc. Phys.
Photoproduction of mesons in ultraperipheral heavy ion collisions at energies available at the BNL Relativistic Heavy Ion Collider (RHIC) and CERN Large Hadron Collider (LHC)
We investigate the photoproduction of mesons in ultraperipheral heavy
ion collisions at RHIC and LHC energies in the dipole approach and within two
phenomenological models based on the the Color Glass Condensate (CGC)
formalism. We estimate the integrated cross section and rapidity distribution
for meson production and compare our predictions with the data from the STAR
collaboration. In particular, we demonstrate that the total cross section at
RHIC is strongly dependent on the energy behavior of the dipole-target cross
section at low energies, which is not well determined in the dipole approach.
In contrast, the predictions at midrapidities at RHIC and in the full rapidity
at LHC are under theoretical control and can be used to test the QCD dynamics
at high energies.Comment: 6 pages, 5 figures, 1 table. Improved version to be published in
Physical Review
Gluon saturation and the Froissart bound: a simple approach
At very high energies we expect that the hadronic cross sections satisfy the
Froissart bound, which is a well-established property of the strong
interactions. In this energy regime we also expect the formation of the Color
Glass Condensate, characterized by gluon saturation and a typical momentum
scale: the saturation scale . In this paper we show that if a saturation
window exists between the nonperturbative and perturbative regimes of Quantum
Chromodynamics (QCD), the total cross sections satisfy the Froissart bound.
Furthermore, we show that our approach allows us to describe the high energy
experimental data on total cross sections.Comment: 6 pages, 5 figures. Includes additional figures, discussion and
reference
A note on the cylindrical collapse of counter-rotating dust
We find analytical solutions describing the collapse of an infinitely long
cylindrical shell of counter-rotating dust. We show that--for the classes of
solutions discussed herein--from regular initial data a curvature singularity
inevitably develops, and no apparent horizons form, thus in accord with the
spirit of the hoop conjecture.Comment: 8 pages, LaTeX, ijmpd macros (included), 1 eps figure; accepted for
publication in Int. J. Mod. Phys.
Vector Meson Production in Coherent Hadronic Interactions: An update on predictions for RHIC and LHC
In this letter we update our predictions for the photoproduction of vector
mesons in coherent and collisions at RHIC and LHC energies using the
color dipole approach and the Color Glass Condensate (CGC) formalism. In
particular, we present our predictions for the first run of the LHC at half
energy and for the rapidity dependence of the ratio between the and
cross sections at RHIC energies.Comment: 4 pages, 3 figure
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