Using VH Associated Production to Search for the $b\bar{b}$ Decay of the Higgs Boson with Data from the ATLAS Detector at $\sqrt{s}=13\mathrm{TeV}$

Two analyses, using the vector-boson-associated production of the Higgs boson in which the Higgs then decays to a pair of \(b\)-quarks using data collected with the \atlas\ detector during 2015 and 2016 at a center-of-mass energy of \(\sqrt{s}=\SI{13}{\tera\electronvolt}\), are presented. The first analysis focuses on the Standard Model interpretation with the expressed goal of observing the \(H\rightarrow b\bar{b}\) decay. The second analysis searches for an additional Higgs boson in the context of the Two-Higgs Doublet Model extension of the Standard Model that resolves some of the outstanding issues the Standard Model has such as baryogenesis. Both analyses aim to take advantage of the large predicted branching ratio of the Higgs boson to \(b\)-quarks. The primary backgrounds in both analyses are the production of a Standard Model vector boson with two additional jets and, also, \(t\)-quark pair-production. The Standard Model analysis leverages a multivariate algorithm for better signal-to-background separation while the non-Standard Model analysis is primarily cut-based. Both use a global likelihood fit to assess the presence of signal within the constraints imposed by systematic uncertainties. A prominent source of uncertainty in both analyses is the uncertainties arising from the identification of \(b\)-quarks. A portion of my analytic and technical contribution is the estimation and ultimate reduction of these uncertainties.