Study of the modelling of $W/Z + HF$ as background for $VH(H \to b \bar b)$ at ATLAS

The Higgs boson properties has been measured at the ATLAS experiment since its discovery, obtaining a good agreement with the Standard Model predictions. Evidence of $H \to b \bar b$ is crucial for constraining the overall Higgs boson decay width and to confirm the Yukawa coupling to quark sector. The most promising production mode is the VH, where the Higgs boson is in association with a vector boson. The vector boson decaying into leptons helps in the extraction of the signal from the multijet background which dominates the $H \to b \bar b$. One of the main sources of background for the Standard Model $VH(H \to b \bar b)$ search is the production of $V (V = W $or $ Z)$ bosons in the association with jets. This contribution describes the ATLAS simulation setup used to model this irriducible background in proton-proton collisions at centre-of-mass energy of 13 TeV. Several Monte Carlo generators are studied in different phase-space regions and compared to unfolded data distribution, with additional requirements on the heavy-flavour content of the associated jets.