Measuring the $b$-jet identification efficiency for high $p_{\text{T}}$ jets using multijet events in proton$-$proton collisions at $\sqrt{s} = 13$ TeV recorded with the ATLAS detector

The identification of jets containing $b$-hadrons, or $b$-tagging, is crucial to many physics analyses using data collected with the ATLAS detector at the Large Hadron Collider. This work presents the measurement of the $b$-tagging efficiency ($\epsilon_{b}$), the probability of a $b$-flavor jet to pass a given $b$-tagging criterion, using multijet events, considering jets with geometrically matched muons. The jet $p_{\text{T}}$ range considered starts from 500 GeV to 1.2 TeV, greatly extending the kinematic coverage of the previous calibrations. A discriminant variable is constructed using tracking properties and a profile-likelihood fit to this variable in data is performed to extract the fractions of $b$-flavor jets in samples passing and failing the $b$-tagging criterion. The flavor fractions are then used to calculate $\epsilon_{b}$ in data. The results are presented as the correction (scale factor) to simulation, which is the ratio between the $\epsilon_{b}$ in data and that in simulation. Scale factors are measured for the DL1r tagger at four different operating points, corresponding to 60%, 70%, 77% and 85% fixed $\epsilon_{b}$ expected in simulation, and presented in three jet $p_{\text{T}}$ bins.