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

• Author(s): Castro, N. F. ; Fiolhais, M. C. N. ; Gonçalo, J. R. ; Onofre, A. ; Veloso, F. ; Wolters, H. ; Atlas Collaboration
• Date: 2022
• Persistent ID: https://hdl.handle.net/10316/103242
• Origin: Estudo Geral - Universidade de Coimbra
• Document Type: Journal article
• Language: English

Description

A technique is presented to measure the efficiency with which c-jets are mistagged as b-jets (mistagging efficiency) using t ¯t events, where one of theW 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 ameasurement 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 t ¯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.