8 research outputs found
Investigating the high energy QCD approaches for prompt photon production at the LHC
We investigate the rapidity and transverse momentum distributions of the
prompt photon production at the CERN LHC energies considering the current
perturbative QCD approaches for this scattering process. Namely, we compare the
predictions from the usual NLO pQCD calculations to the the color dipole
formalism, using distinct dipole cross sections. Special attention is paid to
parton saturation models at high energies, which are expected to be important
at the forward rapidities in pp collisions at the LHC.Comment: Contribution to the proceedings of the 3rd International Conference
on Hard and Electro-Magnetic Probes of High-Energy Nuclear Collisions (Hard
Probes 2008), 8-14 June 2008, Illa da Toxa (Galicia-Spain). Talk presented by
M.V.T. Machad
Using dileptons to probe the Color Glass Condensate
The rapidity and transverse momentum dependence of the nuclear modification
ratio for dilepton production at RHIC and LHC is presented, calculated in the
Color Glass Condensate (CGC) framework. The transverse momentum ratio is
compared for two distinct dilepton mass values and a suppression of the Cronin
peak is verified even for large mass. The nuclear modification ratio
suppression in the dilepton rapidity spectra, as obtained experimentally for
hadrons at RHIC, is verified for LHC energies at large transverse momentum,
although not present at RHIC energies. The ratio between LHC and RHIC nuclear
modification ratios is evaluated in the CGC, showing the large saturation
effects at LHC compared with the RHIC results. These results consolidate the
dilepton as a most suitable observable to investigate the QCD high density
approaches.Comment: 5 pages, version to appear in Phys. Lett.
Non-linear QCD dynamics and exclusive production in collisions
The exclusive processes in electron-proton () interactions are an
important tool to investigate the QCD dynamics at high energies as they are in
general driven by the gluon content of proton which is strongly subject to
parton saturation effects. In this paper we compute the cross sections for the
exclusive vector meson production as well as the deeply virtual Compton
scattering (DVCS) relying on the color dipole approach and considering the
numerical solution of the Balitsky-Kovchegov equation including running
coupling corrections. We show that the small- evolution given by this
evolution equation is able to describe the DESY-HERA data and is relevant for
the physics of the exclusive observables in future electron-proton colliders
and in photoproduction processes to be measured in coherent interactions at the
LHC.Comment: 6 pages, 4 figure
Non-linear QCD dynamics in two-photon interactions at high energies
Perturbative QCD predicts that the growth of the gluon density at high
energies should saturate, forming a Color Glass Condensate (CGC), which is
described in mean field approximation by the Balitsky-Kovchegov (BK) equation.
In this paper we study the interactions at high energies and
estimate the main observables which will be probed at future linear colliders
using the color dipole picture. We discuss in detail the dipole - dipole cross
section and propose a new relation between this quantity and the dipole
scattering amplitude. The total ,
cross-sections and the real photon structure function are
calculated using the recent solution of the BK equation with running coupling
constant and the predictions are compared with those obtained using
phenomenological models for the dipole-dipole cross section and scattering
amplitude. We demonstrate that these models are able to describe the LEP data
at high energies, but predict a very different behavior for the observables at
higher energies. Therefore we conclude that the study of
interactions can be useful to constrain the QCD dynamics.Comment: 11 pages, 5 figures. Version to be published in European Physical
Journal