Both hard and soft QCD dynamics are important in charmonium production, as presented here through a next-to-leading order QCD matrix element calculation combined with the colour evaporation model. Observed x F and p ⊥ distributions of J/ψ in hadroproduction at fixed target and pp collider energies are reproduced. Quite similar results can also be obtained in a more phenomenologically useful Monte Carlo event generator where the perturbative production of cc pairs is instead obtained through leading order matrix elements and the parton shower approximation of the higher order processes. The soft dynamics may alternatively be described by the soft colour interaction model, originally introduced in connection with rapidity gaps. We also discuss the relative rates of different charmonium states and introduce an improved model for mapping the continuous cc mass spectrum on the physical charmonium resonances.

Abstract. We investigate the heavy quark photoproduction based on the k ⊥ -factorization approach, focusing on the results from the saturation model. The deviations in the results using the unintegrated gluon distribution considering the saturation model and the derivative of the collinear gluon distribution are analysed. Total cross sections and p T distributions are analysed in detail, setting the deviations between the color dipole approximation and the complete semihard approach.

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 ( √ s = 14 TeV) at the LHC.

Our goal is the study of color effects on the J/ψ and D mesons production, as well as the study of their elastic production.We use the Color Evaporation Model (CEM), where a single factor takes into account the probability that the cc produced in a color octet state turns into a physical (colorless) quarkonium or continues as a color octet, producing open charm.The main result of this work, besides investigating the range of applicability of the CEM, is to show that this model can be used to describe the elastic processes of J/ψ and open charm photoproduction without the use of a Pomeron.