Implicações fenomenológicas do charme intrínseco no grande colisor de hádrons

Abstract

The Standard Model of Particle Physics describes the hadron in terms of quarks and gluons. Especially, the precise knowledge about quarks components is fundamental to determine physics Beyond the Standard Model. Most of the global analyses assume that the charm quark distribution functions are generated perturbatively by gluon splitting, however in the literature we find predictions that believe in a non-perturbative heavy quarks component intrinsic to the proton wavefunction. It is important to distinguish two types of contributions to the hadron quark distributions: extrinsic and intrinsic. The extrinsic quark is generated perturbatively by QCD evolution and carries small fraction of momentum, because of this we find extrinsic components in small rapidity regions. The intrinsic quark is generated non-perturbatively and is related with hadron light quarks and intrinsic components carries large fraction of momentum and they are found in large rapidity regions. In this work, we investigate the existence of an intrinsic charm component in the proton. Nowadays, it does not exist an experimental evidence about intrinsic charm, so this is an open topic and in constant discussion. In this thesis, we study the phenomenological implications of charm in cases involving the gauge bosons W and Z and to processes involving gauge bosons associated with the charm quark, p + p ! γ + c e p + p ! Z + c, where we analyzed the cross sections using the CTEQ parametrizations, considering all intrinsic charm models. Our results indicate that the best kinematic regions to prove experimentally the intrinsic charm is the forward rapidity region with a large-transverse-momentum and a small center of mass energy.