Performance and calibration of quark/gluon-jet taggers using 140 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 13$ TeV with the ATLAS detector

TL;DR

This study evaluates the performance and calibration of quark/gluon jet taggers using extensive ATLAS data, providing insights into their efficiencies and differences between data and simulation for high-energy jets.

Contribution

It introduces a method to measure quark/gluon tagging efficiencies with large LHC data and compares data with simulation for improved jet identification.

Findings

High-performance quark/gluon taggers are validated.

Differences between data and simulation are quantified.

Efficiency measurements cover jets with 500 GeV to 2 TeV.

Abstract

The identification of jets originating from quarks and gluons, often referred to as quark/gluon tagging, plays an important role in various analyses performed at the Large Hadron Collider, as Standard Model measurements and searches for new particles decaying to quarks often rely on suppressing a large gluon-induced background. This paper describes the measurement of the efficiencies of quark/gluon taggers developed within the ATLAS Collaboration, using $\sqrt{s} = 13$ TeV proton-proton collision data with an integrated luminosity of 140 fb$^{-1}$ collected by the ATLAS experiment. Two taggers with high performances in rejecting jets from gluon over jets from quarks are studied: one tagger is based on requirements on the number of inner-detector tracks associated with the jet, and the other combines several jet substructure observables using a boosted decision tree. A method is established to determine the quark/gluon fraction in data, by using quark/gluon-enriched subsamples defined by the jet pseudorapidity. Differences in tagging efficiency between data and simulation are provided for jets with transverse momentum between 500 GeV and 2 TeV and for multiple tagger working points.