Investigating the exclusive protoproduction of dileptons at high energies

Using the high energy color dipole approach, we study the exclusive photoproduction of lepton pairs. We use simple models for the elementary dipole-hadron scattering amplitude that captures main features of the dependence on atomic number A, on energy and on momentum transfer t. This investigation is complementary to conventional partonic description of timelike Compton scattering, which considers quark handbag diagrams at leading order in $\alpha_s$ and simple models of the relevant generalized parton distributions (GPDs). These calculations are input in electromagnetic interactions in pp and AA collisions to measured at the LHC.Comment: 6 pages, 4 figure

Neutrino structure functions in the QCD dipole picture

In this contribution we present an exploratory QCD analysis of the neutrino structure functions in charged current DIS using the color dipole formalism. The corresponding dipole cross sections are taken from recent phenomenological and theoretical studies in deep inelastic inclusive production, including nuclear shadowing corrections. The theoretical predictions are compared to the available experimental results in the small-x region.Comment: 4 pages, 2 figures. To appear in the proceedings of the XXXVI International Symposium on Multiparticle Dynamics. September 02-08, 2006 Paraty, Rio de Janeiro, Brazi

Nuclear Heavy Quark Photoproduction in a Saturation Model

We calculate the nuclear inclusive and diffractive cross sections for heavy quark photoproduction within a phenomenological saturation approach. The nuclear cross section is obtained by the extension of the saturation model through Glauber-Gribov formalism. We predict large nuclear heavy quark cross section at LHC energies.Comment: 14 pages, 6 figures. Version to be published in Eur. Phys. J.

Diffractive photoproduction of Z^0 bosons in coherent interactions at CERN-LHC

The exclusive $Z^0$ photoproduction at high energies in $\gamma p (A)$, $p p$ and $AA$ collisions is investigate within the color dipole formalism. We generalize the description of the deeply virtual compton scattering (DVCS) process, which describe quite well the HERA data, for the production of $Z^0$ bosons and estimate the total cross section for the exclusive process $\gamma^* h\to Z^0 h$ ($h=p,A$) for different energies, photon virtualities and atomic numbers. As hadrons at collider energies are a source of Weizs\"{a}cker - Williams photons, we consider electromagnetic interactions in hadron-hadron collisions at Tevatron and LHC energies and estimate the rapidity distribution and total cross section for $Z^0$ production in the $h h\to h Z^0 h$ process. This is the first estimation for such a process in literature. It can allow us to study, for instance, the physics of hadronic $Z^0$ decays in a clean environment characterized by two rapidity gaps. Our results indicate that the experimental analyzes of this process could be feasible in $pp$ but the physics scenario for $AA$ collisions is not promising.Comment: 6 pages, 2 figures, 1 table; The erroneus additional factor of $2\pi$ in the normalization of the cross sections is removed. Figures and table are update