Electron efficiency measurements with the ATLAS detector using 2012 LHC proton-proton collision data

TL;DR

This paper details the electron reconstruction and identification algorithms used in ATLAS during 2012, measuring their efficiency and charge misidentification rate with collision data at 8 TeV, achieving high efficiency levels.

Contribution

It introduces a new electron reconstruction algorithm and provides detailed efficiency measurements using the full 2012 LHC dataset.

Findings

Electron reconstruction efficiency reaches 97% at 15 GeV and 99% at 50 GeV.

Overall electron identification efficiency varies from 65% to 95%.

Charge misidentification rates are evaluated and reported.

Abstract

This paper describes the algorithms for the reconstruction and identification of electrons in the central region of the ATLAS detector at the Large Hadron Collider (LHC). These algorithms were used for all ATLAS results with electrons in the final state that are based on the 2012 pp collision data produced by the LHC at $\sqrt{\mathrm{s}}$ = 8 TeV. The efficiency of these algorithms, together with the charge misidentification rate, is measured in data and evaluated in simulated samples using electrons from $Z\rightarrow ee$, $Z\rightarrow ee\gamma$ and $J/\psi \rightarrow ee$ decays. For these efficiency measurements, the full recorded data set, corresponding to an integrated luminosity of 20.3 fb$^{-1}$, is used. Based on a new reconstruction algorithm used in 2012, the electron reconstruction efficiency is 97% for electrons with $E_\mathrm{T}=15$ GeV and 99% at $E_\mathrm{T} = 50$ GeV. Combining this with the efficiency of additional selection criteria to reject electrons from background processes or misidentified hadrons, the efficiency to reconstruct and identify electrons at the ATLAS experiment varies from 65% to 95%, depending on the transverse momentum of the electron and background rejection.