Observation and Measurement of the Higgs Boson Produced in Association with a Vector Boson and Decaying to a Pair of Bottom Quarks with the ATLAS Detector at LHC

A search of the Higgs boson decaying into $b\bar{b}$ pair using the $WH$ and $ZH$ associated production is performed with the ATLAS detector. The analyzed data were collected in 2015, 2016, 2017 and 2018 LHC Run-2 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 139 fb${}^{-1}$. Final states that contains 0, 1, and 2 charged leptons (electrons or muons, denoted as $\ell$) are considered, to target the processes of $Z \rightarrow \nu\nu$, $W \rightarrow \ell \nu$ and $Z \rightarrow \ell\ell$. Object reconstruction, event selection, and signal and control region definition are included. Systematic uncertainty and statistical analysis used to extract the final results are presented. This analysis observes the production $pp \rightarrow (W, Z)H$ in $H \rightarrow b\bar{b}$ channel at a significance of 6.7 standard deviations (where the expectation is 6.7 standard deviations) and represents the most precise observation to date of this physics process. Cross-sections of $VH$ ($WH$ and $ZH$) with $V \rightarrow \text{leptons}$ and $H \rightarrow b\bar{b}$ are measured as a function of the vector boson transverse momentum in the kinematic fiducial volumes and found to be consistent with the Standard Model predictions.