Coherent photon-hadron interactions in pA collisions: Small-x physics after HERA

In this letter we study the photoproduction of heavy quarks and vector mesons in the coherent proton-nucleus (pA) interactions for RHIC and LHC energies and analyze if these processes can be used to determine the QCD dynamics at high energies. The integrated cross section and rapidity distribution are estimated using the Color Glass Condensate (CGC) formalism. A comparison with the linear dynamics predictions is also presented. Our results indicate that the nonlinear dynamics can be proven in those reactions, which are well suited for studing saturation effects.Comment: 5 pages, 3 figures. Version to be published in Physical Review

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

The QCD Pomeron in Ultraperipheral Heavy Ion Collisions: II. Heavy Quark Production

The heavy quark production in ultraperipheral heavy ion collisions is investigated, in particular we focus on the results from the coherent interactions given by the two-photon process. One addresses the heavy quark total cross sections at photon level considering the saturation model and the BFKL dynamics in the color dipole picture. The corresponding cross sections at nuclear level are presented. It is verified that the QCD dynamics implies an enhancement of the cross section in comparison with previous calculations.Comment: 16 pages, 7 figures. Version to be published in Eur. Phys. J.

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.