112 research outputs found
The DLLA limit of BFKL in the Dipole Picture
In this work we obtain the DLLA limit of BFKL in the dipole picture and
compare it with HERA data. We demonstrate that in leading-logarithmic-
approximation, where is fixed, a transition between the BFKL
dynamics and the DLLA limit can be obtained in the region of . We compare this result with the DLLA predictions obtained with
running. In this case a transition is obtained at low . This demonstrates the importance of the next-to-leading order
corrections to the BFKL dynamics. Our conclusion is that the structure
function is not the best observable for the determination of the dynamics,
since there is great freedom in the choice of the parameters used in both BFKL
and DLLA predictions.Comment: 14 pages, 2 figures, Accepted for publication in Phys. Lett.
Seeking the Shadowing in eA Processes
We consider the behavior of the slope of the nuclear structure function
in the kinematic region which will be explored in the eA HERA collider.
We demonstrate that, similarly to the nucleon case, a `turn over' is predicted
in this observable. Moreover, we predict that the presence of the shadowing
corrections implies that the maximum value of the slope is dependent of the
number of nucleons A, differently from the DGLAP predictions. Our conclusion is
that the measurement of this observable will allow to evidentiate the presence
of the shadowing corrections.Comment: 10 pages, 1 figur
The AGL Equation from a 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 regime. This equation was originally obtained
using the Glauber-Mueller approach. We demonstrate in this contribution that
the AGL equation can also be obtained from the dipole picture. Our conclusion
is that the AGL equation is a good candidate for an unitarized evolution
equation at small in the DLA limit.Comment: 3 pages. To be published in the proceedings of 7th International
Workshop on Deep Inelastic Scattering and QCD (DIS 99), Zeuthen, Germany, 19
- 23 Apr 199
Quarkonium+ production in coherent hadron - hadron interactions at LHC energies
In this paper we study the ( and )
production in coherent hadron - hadron interactions at LHC energies.
Considering the ultrarelativistic protons as a source of photons, we estimate
the cross section using the
non-relativistic QCD (NRQCD) factorization formalism and considering different
sets of values for the matrix elements. Our results for the total cross sections and rapidity distributions at
and 14 TeV demonstrate that the experimental analysis of the
production at LHC is feasible.Comment: 6 pages, 3 figures, 1 table. Improved version with a new figure.
Version to be published in European Physical Journal
The QCD Pomeron in Ultraperipheral Heavy Ion Collisions: V. Double Vector Meson Production in the BFKL Approach
In this work the double vector meson production in ultraperipheral heavy ion
collisions is investigated within the BFKL approach. The integrated cross
sections and event rates for the processes AA --> V1 V2 AA (V_i = rho, omega,
phi, J/Psi, Upsilon) are computed and theoretical estimates for scattering on
both light and heavy nuclei are given for energies of RHIC and LHC.Comment: 10 pages, 1 figure. Version to be published in the European Physical
Journal
Saturation Physics in Ultra High Energy Cosmic Rays: Heavy Quark Production
In this work we estimate the heavy quark production in the interaction of
ultra high energy cosmic rays in the atmosphere, considering that the primary
cosmic ray is a proton or a photon. At these energies the saturation momentum
Q_{sat}^2 stays above the hard scale \mu_c^2=4m_c^2, implying charm production
probing the saturation regime. In particular, we show that the ep HERA data
presents a scaling on \tau_c = (Q^2+\mu_c^2)/Q_{sat}^2. We derive our results
considering the dipole picture and the Color Glass Condensate formalism, which
one shows to be able to describe the heavy quark production in photon-proton
and proton-proton collisions. Nuclear effects are considered in computation of
cross sections for scattering on air nuclei. Implications on the flux of prompt
leptons at the earth are analyzed and a large suppression is predicted.Comment: 18 pages, 10 figures, 2 tables. Version to be published in JHE
Constraining the free parameter of the high parton density effects
The high density parton effects are strongly dependent of the spatial gluon
distribution within the proton, with radius , which cannot be derived from
perturbative QCD. In this paper we assume that the unitarity corrections are
present in the HERA kinematical region and constrain the value of using the
data for the proton structure function and its slope. We obtain that the gluons
are not distributed uniformly in the whole proton disc, but behave as
concentrated in smaller regions.Comment: 16 pages, 5 figure
Searching Saturation in eA Processes
The high density effects should be manifest at small x and/or large nuclei.
In this letter we consider the behavior of nuclear structure function
slope in the kinematic region which could be explored in the future eA
colliders as a search of these effects. We verify that the high density implies
that the maximum value of the slope occurs at large values of the photon
virtuality, i.e. in a perturbative regime, and is dependent of the number of
nucleons A and energy. Our conclusion is that the measurement of this
observable will allow to explicit the saturation.Comment: 13 pages, 2 figures, 1 tabl
Dipole model for double meson production in two-photon interactions at high energies
In this work the double vector meson production in two-photon interactions at
high energies is investigated considering saturation physics. We extend the
color dipole picture for this process and study the energy and virtuality
dependence of the forward differential cross section. Comparison with previous
results is presented and the contribution of the different photon polarizations
is estimated.Comment: 20 pages, 8 figures, 1 table. Version to be published in European
Physical Jornal
Charm production in diffractive deep inelastic scattering
The diffractive open charm production is computed in perturbative QCD
formalism and in the Regge approach. The results are compared with recent data
on charm diffractive structure function measured at DESY-HERA. Our results
demonstrate that this observable can be useful to discriminate the QCD
dynamics.Comment: LaTeX, 13 pages, 2 figures. Version to be published in Phys. Lett.
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