Probing high energy Higgs bosons using $H\rightarrow b\bar{b}$ decays in $\sqrt{s} = 13$ TeV proton-proton collisions at the ATLAS experiment

This thesis presents a novel study of Higgs boson production using $H\rightarrow b\bar{b}$ decays produced with large transverse momentum boosts, with an additional high energy jet in the event, using $\sqrt{s}=13$ TeV proton-proton collision data collected by the ATLAS experiment, corresponding to an integrated luminosity of 136 fb$^{-1}$. Higgs boson signal estimates were extracted from candidate jet mass spectra using binned likelihood fits. The Higgs boson signal estimate was probed inclusively using Higgs boson candidate jets with $p_T^{\text{jet}}>250$ GeV. The inclusive Higgs boson production cross-sections were examined in a fiducial region defined by Higgs boson $p_T^H>450$ GeV, and differential bins of $p_T^H = [300, 450]$ GeV; $[450, 650]$ GeV; $[650, 1000]$ GeV; and $>1000$ GeV inclusively. As sensitivity was not sufficient to make statistically significant measurements of the Higgs boson cross-section, in all cases 95% $CL_s$ limits were set, including a first-time limit set for Higgs bosons with $p$$_{T}^{H}$ > 1 TeV, $\sigma$$_{H}$ ($p$$_{T}^{H}$ > 1 TeV) < 74 fb. A differential $Z$ boson signal measurement was also made under the same conditions and compared to theoretical predictions. All results were found to be consistent with Standard Model predictions. Particular emphasis is given to the development and validation of the analysis fit model.