QCD Radiative Corrections to Higgs Physics[HBNI Th114]

Abstract

The central part of this thesis deals with the QCD radiative corrections to some important observables associated with the Drell-Yan, scalar and pseudo scalar Higgs boson productions at three loop or N 3 LO order aiming to uplift the accuracy of theoretical results. The Higgs bosons are produced dominantly at the LHC via gluon fusion through top quark loop, while one of the subdominant ones take place through bottom quark annihi- lation. However, in some BSM theories, like minimally supersymmetric Standard Model (MSSM), it can contribute substantially. Here, we have computed analytically the in- clusive cross section of the Higgs boson produced in this channel under the soft-virtual (SV) approximation at N 3 LO QCD following an elegant formalism. This indeed helps to reduce the theoretical uncertainties arising from renormalisation and factorisation scales and consequently improve the reliabilities of the theoretical results. This is the most accurate result for this channel which exists in the literature. The differential rapidity distribution is among the most important observables, which is expected to be measured in upcoming days at the LHC. This immediately calls for very precise theoretical predictions. The SV corrections to this observable at N 3 LO for the Higgs boson, produced through gluon fusion, and leptonic pair in Drell-Yan (DY) production are computed and the numerical impacts of these results are demonstrated. These are the most accurate results for the rapidity distributions of these which exist and undoubtedly, expected to play very important role in the upcoming run at the LHC. The CP-odd/pseudo-scalar Higgs boson is one of the most prime candidates in BSM which has been studied in great details, taking into account higher order QCD radiative corrections, due to similarities with its CP-even counter part. In this thesis, we have obtained the three loop QCD corrections to the pseudo scalar Higgs boson production and computed the SV correction to the inclusive production cross section.