Measurements of the production cross-section for a $Z$ boson in association with $b$-jets in proton-proton collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

The collaboration
JHEP 07 (2020) 044, 2020.

Abstract (data abstract)
This paper presents the first measurement of the production cross-section of a $Z$ boson in association with $b$-jets, in proton-proton collisions at $\sqrt{s}$​ = 13 TeV. The measurement has been completed at the ATLAS experiment at the Large Hadron Collider using data corresponding to an integrated luminosity of 35.6 fb$^{−1}$. Inclusive and differential cross-sections are measured for events containing a $Z$ boson decaying into electrons or muons and produced in association with at least one or at least two b-jets with transverse momentum $p_{\text{T}}​>$ 20 GeV and rapidity $|y| <$2.5. Fiducial region definition commont to all measured cross-sections: - 2 electrons or 2 muons of opposite charge, $p_{\text{T}}>$27 GeV, $|\eta|<2.5$, $76<M_{\ell\ell}<106$ GeV - At least one jet, reconstructed using anti-kT of R=0.4, of $p_{\text{T}}>20$ GeV, |y|<2.5, $\Delta$ $R(jet, lepton)>0.4$ - b-jets defined as jets containing at least one b-hadron of $p_{\text{T}}>5$ GeV within $\Delta$ $R(jet, b-hadron)>0.3$