Processos difrativos em colisões hadrônicas à altas energias

Abstract

High energy hadronic collisions can be classified, according to the final observed state, as elastic and inelastic. Inelastic collisions can be divided into inclusive and diffractive. Inclusive processes are dominant at the LHC, representing about 60% of the total observed interactions. Diffractive processes also represent a significant part of the events that occurred at the LHC, but the full description of such reactions has yet to be improved. In this thesis we study the diffractive processes in high energy hadronic collisions, aiming to better understand the phenomenon and provide ways to improve their theoretical description. For this purpose, we calculated the cross sections for the double diffractive production of vector mesons in proton-proton collisions, adopting the fatorization scheme of non-relativistic quantum chromodynamics together with the resolved Pomeron model. In addition, we calculated the cross sections for diffractive dissociation in proton-proton and proton-nucleus collisions considering the Miettinen-Pumplin model. Our results indicate that the study of the production of quarkonia pairs can be useful to probe the underlying hypotheses present in the description of diffractive processes. Additionally, we calculated the cross sections for the double production of quarkonia in an central exclusive process. We found that the diffractive and exclusive processes, with the same final states, can be discriminated by observing the transverse momentum distribution of the cross section. Regarding the use of the Miettinen-Pumplin model to calculate diffractive dissociation, we demonstrated that this model can satisfactorily describe the most current experimental data, and that it can also be used to derivate the main quantities that describe proton-nucleus interactions. The results presented in this thesis indicate that the study of diffractive events at the LHC and in future colliders will allow us to expand our understanding of the dynamics of strong interactions in the high energy regime.