Higgs Boson Phenomenology at the LHC: the Standard Model and Beyond

Since the discovery of the Higgs boson at the LHC in 2012, its properties and interactions have been extensively studied, providing insight into electroweak symmetry breaking and testing the nature of new physics beyond the Standard Model. With upgrades to the LHC and increasing amounts of data, new territories are now accessible for probing rare decays of the Higgs boson and its couplings at high energy regimes. This thesis presents four studies exploring the Higgs boson's couplings to other particles and its connections to BSM physics at the future High Luminosity LHC (HL-LHC). These studies include a novel search strategy for the decay of the Higgs boson to charm quarks, exploring new physics scenarios in the off-shell Higgs boson measurement, probing the coupling of the Higgs boson and top quark, and investigating the high momentum regime of the Higgs boson production through VBF. These studies demonstrate the potential for new physics discoveries and highlight the importance of continued exploration of the Higgs boson's properties and interactions at the HL-LHC.