Electron and photon efficiencies in LHC Run 2 with the ATLAS experiment

TL;DR

This paper reports precise measurements of electron and photon efficiencies in the ATLAS experiment during LHC Run 2, showing significant improvements over previous results due to enhanced methods and larger data samples.

Contribution

It provides updated, more accurate electron and photon efficiency measurements for the ATLAS detector using the full Run 2 dataset, with reduced uncertainties and improved methodologies.

Findings

Electron identification uncertainties reduced by 30-50%.

Photon identification uncertainties reduced by 30-40%.

Enhanced pile-up subtraction improves electron isolation efficiency.

Abstract

Precision measurements of electron reconstruction, identification, and isolation efficiencies and photon identification efficiencies are presented. They use the full Run 2 data sample collected by the ATLAS experiment in $pp$ collisions at a centre-of-mass energy of 13 TeV during the years 2015-2018, corresponding to an integrated luminosity of 139 $\mathrm{fb}^{-1}$. The measured electron identification efficiencies have uncertainties that are around 30%-50% smaller than the previous Run 2 results due to an improved methodology and the inclusion of more data. A better pile-up subtraction method leads to electron isolation efficiencies that are more independent of the amount of pile-up activity. Updated photon identification efficiencies are also presented, using the full Run 2 data. When compared to the previous measurement, a 30%-40% smaller uncertainty is observed on the photon identification efficiencies, thanks to the increased amount of available data.