Abstract
A technique is presented to measure the efficiency with which c-jets are mistagged as b-jets (mistagging efficiency) using tbar{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 Wrightarrow 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 tbar{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.
Highlights
The algorithms for the identification of jets containing bhadrons, known as b-tagging algorithms, constitute an important tool for the analysis of the data collected by the ATLAS experiment [1] at the Large Hadron Collider (LHC) [2]
The analysis aims to obtain a pure sample of semileptonic ttevents
The method described below is for the ‘pseudo-continuous’ calibration where the efficiency is defined as the fraction of c-jets that have a DL1r discriminant value that lies between the boundaries, i.e. a value greater than the 60% boundary, a value between the 70% and 60% boundaries, etc
Summary
The algorithms for the identification of jets containing bhadrons, known as b-tagging algorithms, constitute an important tool for the analysis of the data collected by the ATLAS experiment [1] at the Large Hadron Collider (LHC) [2]. Such algorithms play a crucial role in a large number of Standard Model (SM) precision measurements This paper discusses a complementary technique to measure the inclusive c-jet mistagging efficiency by means of a c-jet sample that is derived from ttevents. The technique has the advantage that it does not depend on a specific hadron decay chain topology
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