ATLAS b-jet identification performance and efficiency measurement with $$t{\bar{t}}$$ events in pp collisions at $$\sqrt{s}=13$$ TeV
G. Aad (CPPM, Aix-Marseille Université, CNRS/IN2P3, Marseille, France); B. Abbott (Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK, USA); D. Abbott (Department of Physics, University of Massachusetts, Amherst, MA, USA); A. Abud (INFN Sezione di Pavia, Pavia, Italy, Dipartimento di Fisica, Università di Pavia, Pavia, Italy); K. Abeling (II. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany); et al - Show all 2930 authors
The algorithms used by the ATLAS Collaboration during Run 2 of the Large Hadron Collider to identify jets containing b-hadrons are presented. The performance of the algorithms is evaluated in the simulation and the efficiency with which these algorithms identify jets containing b-hadrons is measured in collision data. The measurement uses a likelihood-based method in a sample highly enriched in $$t{\bar{t}}$$ events. The topology of the $$t \rightarrow W b$$ decays is exploited to simultaneously measure both the jet flavour composition of the sample and the efficiency in a transverse momentum range from 20 to 600 GeV. The efficiency measurement is subsequently compared with that predicted by the simulation. The data used in this measurement, corresponding to a total integrated luminosity of 80.5 $$\hbox {fb}^{-1}$$ , were collected in proton–proton collisions during the years 2015–2017 at a centre-of-mass energy $$\sqrt{s}=$$ 13 TeV. By simultaneously extracting both the efficiency and jet flavour composition, this measurement significantly improves the precision compared to previous results, with uncertainties ranging from 1 to 8% depending on the jet transverse momentum.