Measurement of the c-jet mistagging efficiency in $$t\bar{t}$$ events using pp collision data at $$\sqrt{s}=13$$ $$\text {TeV}$$ collected with the ATLAS detector
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 (CERN, Geneva, Switzerland); K. Abeling (II. Physikalisches Institut, Georg-August-Universität Göttingen, Göttingen, Germany); et al - Show all 2915 authors
A technique is presented to measure the efficiency with which c-jets are mistagged as b-jets (mistagging efficiency) using $$t\bar{t}$$ events, where one of the W bosons decays into an electron or muon and a neutrino and the other decays into a quark–antiquark pair. The measurement utilises the relatively large and known $$W\rightarrow cs$$ branching ratio, which allows a measurement to be made in an inclusive c-jet sample. The data sample used was collected by the ATLAS detector at $$\sqrt{s} = 13$$ $$\text {TeV}$$ and corresponds to an integrated luminosity of 139 fb $$^{-1}$$ . Events are reconstructed using a kinematic likelihood technique which selects the mapping between jets and $$t\bar{t}$$ decay products that yields the highest likelihood value. The distribution of the b-tagging discriminant for jets from the hadronic W decays in data is compared with that in simulation to extract the mistagging efficiency as a function of jet transverse momentum. The total uncertainties are in the range 3–17%. The measurements generally agree with those in simulation but there are some differences in the region corresponding to the most stringent b-jet tagging requirement.
