Measurement of the Associated Production of a Higgs Boson Decaying into $b$-quarks with a Vector Boson at High Transverse Momentum with the ATLAS Detector

The observation of the decay of the Higgs boson to a $b\bar{b}$ pair in 2018 provided a confirmation of the Yukawa interaction and the first measurement of a Yukawa coupling to down-type quarks. The experimental challenges that the $H \to b \bar{b}$ decay entails at hadron colliders can be addressed by studying the associated Higgs boson production with a vector boson $V$ decaying leptonically. Following the observation, the main focus is now the study of the Higgs boson production cross section as a function of its transverse momentum $(p_T)$. These measurements are well motivated by a wide range of Beyond the Standard Model (BSM) theories predicting an enhancement of $VH(H \to b \bar{b})$ events at high transverse momentum with respect to the SM expectations. At such high energy regimes, the Higgs boson is highly Lorentz-boosted and the $H \to b \bar{b}$ decay is reconstructed in the detector as a single object with a two-prong substructure, using novel techniques. The paper will illustrate the measurement of $VH(H \to H \to b \bar{b})$ in the boosted regime performed inclusively, as well as in bins of the vector boson transverse momentum, for $p^V_T \in [250,400)$ GeV and $p^V_T \in [400,\infty)$ GeV. Their interpretation using the Effective Field Theory (EFT) framework will also be discussed. The results are based on the full LHC Run 2 dataset collected by the ATLAS experiment, corresponding to an integrated luminosity of 139 fb$^{-1}$.