Abstract
This paper presents the electron and photon energy calibration obtained with the ATLAS detector using about 36 fb−1 of LHC proton-proton collision data recorded at √s=13 TeV in 2015 and 2016. The different calibration steps applied to the data and the optimization of the reconstruction of electron and photon energies are discussed. The absolute energy scale is set using a large sample of Z boson decays into electron-positron pairs. The systematic uncertainty in the energy scale calibration varies between 0.03% to 0.2% in most of the detector acceptance for electrons with transverse momentum close to 45 GeV . For electrons with transverse momentum of 10 GeV the typical uncertainty is 0.3% to 0.8% and it varies between 0.25% and 1% for photons with transverse momentum around 60 GeV . Validations of the energy calibration with J/ψ → e+e− decays and radiative Z boson decays are also presented.
Highlights
A precise calibration of the energy measurement of electrons and photons is required for many analyses performed at the CERN Large Hadron Collider (LHC), among which the studies of the Higgs boson in the two-photon and four-lepton decay channels and precise studies of W and Z boson production and properties
This paper presents the calibration of the energy measurement of electrons and photons achieved with the A√TLAS detector using 36 fb−1 of LHC proton−proton collision data collected in 2015 and 2016 at s = 13 TeV
The calibration scheme comprises a simulation-based optimization of the energy resolution for electrons and photons, corrections accounting for differences between data and simulation, the adjustment of the absolute energy scale using Z boson decays into e+e− pairs, and the validation of the energy scale universality using J/ψ decays decays into e+e− pairs and radiative Z boson decays
Summary
A precise calibration of the energy measurement of electrons and photons is required for many analyses performed at the CERN Large Hadron Collider (LHC), among which the studies of the Higgs boson in the two-photon and four-lepton decay channels and precise studies of W and Z boson production and properties. The calibration scheme comprises a simulation-based optimization of the energy resolution for electrons and photons, corrections accounting for differences between data and simulation, the adjustment of the absolute energy scale using Z boson decays into e+e− pairs, and the validation of the energy scale universality using J/ψ decays decays into e+e− pairs and radiative Z boson decays. This strategy closely follows the procedure used for the final energy calibration applied to the data collected in 2011 and 2012 (Run 1) [1], with updates to reflect the changes in data-taking and detector conditions.
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