The photonuclear production of vector mesons in ultraperipheral heavy-ion collisions is investigated within the QCD color dipole picture, with particular emphasis on the saturation model. The integrated cross section and the rapidity distribution for the $AA \rightarrow V AA$ ( $V = \rho, \omega, \phi, J/\Psi$ ) process are computed and theoretical estimates for scattering on both light and heavy nuclei are given for the energies of RHIC and LHC. A comparison with the recent STAR data on coherent production of $\rho$ mesons is also presented. Furthermore, we calculate the photoproduction of vector mesons in proton-proton collisions at RHIC, Tevatron and LHC energies.

In this Rapid Communication we update our predictions for the photoproduction of vector mesons in coherent pp and AA collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies using the color dipole approach and the Color Glass Condensate 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 J/$\Psi${} and $\rho${} cross sections at RHIC energies.

In this paper we present a comprehensive analysis of exclusive vector-meson photoproduction in $pp$, $p\mathrm{Pb}$ and PbPb collisions at Run 2 LHC energies using the color dipole formalism. The rapidity distributions and total cross sections for the $\rho$, $\varphi$, $J/\mathrm{\Psi }$, $\mathrm{\Psi }(2S)$ and $\mathrm{\Upsilon }$ production are estimated considering the more recent phenomenological models for the dipole-proton scattering amplitude, which are based on the color glass condensate formalism and are able to describe the inclusive and exclusive $ep$ HERA data. Moreover, we also discuss the impact of the modeling of the vector-meson wave functions on the predictions. The current theoretical uncertainty in the color dipole predictions is estimated and a comparison with the experimental results is performed.

One of the frontiers of QCD which are intensely investigated in high energy experiments is the high energy (small $x$) regime, where we expect to observe the non-linear behavior of the theory. In this regime, the growth of the parton distribution should saturate, forming a Color Glass Condensate (CGC). In fact, signals of parton saturation have already been observed both in $ep$ deep inelastic scattering at HERA and in deuteron-gold collisions at RHIC. Currently, the description of the experimental data of these experiments is possible considering different phenomenological saturation models for the two processes within the CGC formalism. In this letter we analyze the universality of these dipole cross section parameterizations and verify that they are not able to describe the HERA and RHIC data simultaneously. We analyze possible improvements in the parameterizations and propose a new parametrization for the forward dipole amplitude which allows us to describe quite well the small-$x$ $ep$ HERA data on $F_2$ structure function as well as the $dAu$ RHIC data on charged hadron spectra. It is an important signature of the universality of the saturation physics.Comment: 12 pages, 4 figures. Version to be published in Physics Letters

In this work we analyze the entanglement entropy in deep inelastic scattering off protons and nuclei. It is computed based on the formalism where the partonic state at small-$x$ is maximally entangled with proton being constituted by large number of microstates occurring with equal probabilities. We consider analytical expressions for the number of gluons, $N_{\text{gluon}}$, obtained from gluon saturation models for the dipole-target amplitudes within the QCD color dipole picture. In particular, the nuclear entanglement entropy per nucleon is studied. We also study the underlying uncertainties on these calculations and compare the results to similar investigations in literature.