Electron and photon reconstruction and identification with the CMS experiment at the CERN LHC

TL;DR

This paper details the CMS experiment's advanced algorithms for reconstructing and identifying electrons and photons, achieving high energy resolution and precise energy scale calibration using extensive proton-proton and heavy-ion collision data at the LHC.

Contribution

It introduces innovative reconstruction techniques and provides detailed performance metrics for electron and photon identification in CMS at 13 TeV.

Findings

Electron energy resolution ranges from 2% to 5%.

Energy scale uncertainty is below 0.3% in proton-proton collisions.

Timing resolution for electrons is 200 ps.

Abstract

The performance is presented of the reconstruction and identification algorithms for electrons and photons with the CMS experiment at the LHC. The reported results are based on proton-proton collision data collected at a center-of-mass energy of 13 TeV and recorded in 2016-2018, corresponding to an integrated luminosity of 136 fb$^{-1}$. Results obtained from lead-lead collision data collected at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV are also presented. Innovative techniques are used to reconstruct the electron and photon signals in the detector and to optimize the energy resolution. Events with electrons and photons in the final state are used to measure the energy resolution and energy scale uncertainty in the recorded events. The measured energy resolution for electrons produced in Z boson decays in proton-proton collision data ranges from 2 to 5%, depending on electron pseudorapidity and energy loss through bremsstrahlung in the detector material. The energy scale in the same range of energies is measured with an uncertainty smaller than 0.1 (0.3)% in the barrel (endcap) region in proton-proton collisions and better than 1 (3)% in the barrel (endcap) region in heavy ion collisions. The timing resolution for electrons from Z boson decays with the full 2016-2018 proton-proton collision data set is measured to be 200 ps.