Search for SM $VH \to b\bar{b}$ with the ATLAS detector

The decay of the Standard Model Higgs to $b\bar{b}$ is the most commonly occurring decay mode, with a branching fraction of approximately 58%. Probing this decay is vital to furthering our understanding of the Higgs sector. Due to the large multijet background, the direct observation of $H \to b\bar{b}$ in the gluon fusion channel is very challenging. Instead, looking for the associated production of a Higgs with a vector boson ($W/Z$), and triggering on leptonic decays of the vector boson provides an effective way to trigger on the $H \to b\bar{b}$ decays and reduce the overwhelming multijet background. This provides one of the most sensitive searches for $H \to b\bar{b}$ decay, and the latest results of this analysis using $36.1~\text{fb}^{-1}$ of Run-2 data are presented. Particular emphasis is given to the one lepton channel, targeting the $WH$ process. This channel is particularly challenging in Run 2 due to the significant increase in the production of $t\bar{t}$ relative to the signal. This has required significant optimisation of the analysis selection to isolate high purity regions that can be used to better control the modelling of the dominant backgrounds. Multivariate algorithms have been applied in the $b$-jet efficiency measurement to reduce the impact of one of the dominant systematic uncertainties by up to 50%. Furthermore, several cross-checks of the fit model have been conducted, and are compared to results using $36.1~\text{fb}^{-1}$.