Towards Higher Theoretical Precision for Electroweak Boson Production with b-Jets at Hadron Colliders

Processes involving the production of electroweak gauge bosons(W±,Z,γ) or a Higgs boson with b jets play a very important role in stress testing the Standard Model and constitute major backgrounds in most searches of new physics beyond the Standard Model at present and future colliders. Given the unprecedented experimental precision that will be reached by the Large Hadron Collider (LHC) experiments during the upcoming Run 3 and the high-luminosity upgrade (HL-LHC), improving the accuracy of theoretical predictions to reach the few-percent level becomes crucial to the success of their physics program. Besides accounting for QCD quantum corrections, this implies including electroweak quantum effects, b-quark mass effects, and effects due to the off-shellness of the final-state boson decaying into leptons or quarks, as well as revisiting approximations that enters in the evolution of a high-energy collision into final-state jets of hadrons. In this thesis we develop a general formalism (massive dipoles and massive 5 flavor scheme) to systematically account for b-quark mass effects at all stages, from the b-quark parton densities in the initial-state protons to the matching of b quarks from the hard scattering to the final-state hadrons via parton shower. Formal results form this thesis have been implemented in the Madisqe framework to allow the general calculation of Standard Model cross sections including the first order of QCD and electroweak corrections and accounting for full b-quark mass effects. Furthermore, they have been used to improve the efficiency and numerical stability of NLOX, a public domain framework for the automated calculation of one-loop Standard Model scattering amplitudes. As a particularly interesting study case, we present in this thesis the case of Z+b jets. The production of a Z boson with bottom quarks can probe both the fundamental properties of b quarks as constituents of hadrons and hadron jets, and represents one of the major backgrounds to precision measurements of Higgs-boson couplings in ZH (H→bƃ) associated production as well as in many searches of new physics. In this thesis, we study in particulat the impact of EW corrections and b-quark mass effects on total and differential rates for Z+b jets at the LHC.