Performance and calibration for the identification of boosted Higgs bosons decaying into beauty quark pairs in ATLAS

These proceedings present the performance and calibration of a new algorithm, the \(X\rightarrow b\bar{b}\) tagger, developed by the ATLAS experiment to identify boosted Higgs bosons decaying in the dominant decay channel to a beauty quark-antiquark pair. Scale factors for the signal efficiency are calculated using \(Z\gamma\) and \(Z+\text{jets}\) events, in four regions of \(p_{\text{T}}\), and vary between \(1.45^{+0.47}_{−0.45}\) and \(0.55^{+0.23}_{-0.22}\), whilst the mis-tag efficiency scale factors are measured using single-lepton \(t\bar{t}\) events, also in four regions of \(p_{\text{T}}\), and vary between \(1.1\pm0.12\) and \(1.0\pm0.16\). The modelling of the large-R jet kinematics is evaluated using multijet events enriched in \(g\rightarrow b\bar{b}\) splitting, achieved by requiring a non-isolated muon contained inside the large-R jet.