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Measurement of the c-jet mistagging efficiency in tt¯ events using pp collision data at √s=13 TeV collected with the ATLAS detector

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Published
Article number95
<mark>Journal publication date</mark>31/01/2022
<mark>Journal</mark>European Physical Journal C
Issue number1
Volume82
Number of pages27
Publication StatusPublished
<mark>Original language</mark>English

Abstract

A technique is presented to measure the efficiency with which c-jets are mistagged as b-jets (mistagging efficiency) using tt¯ 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→ 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 s=13 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 tt¯ 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. © 2022, The Author(s).