Performance of electron reconstruction and selection with the CMS detector in proton-proton collisions at sqrt(s) = 8 TeV

TL;DR

This paper details the methods and performance metrics for electron reconstruction and selection in the CMS detector during 8 TeV proton-proton collisions, emphasizing calibration, efficiency, and resolution.

Contribution

It introduces improved algorithms and benchmark criteria for electron reconstruction, validated with data and Monte Carlo simulations at the CMS experiment.

Findings

Electron momentum resolution ranges from 1.7% to 4.5%.

Momentum scale uncertainty is below 0.3%.

Reconstructed spectra match simulations well.

Abstract

The performance and strategies used in electron reconstruction and selection at CMS are presented based on data corresponding to an integrated luminosity of 19.7 inverse femtobarns, collected in proton-proton collisions at sqrt(s) = 8 TeV at the CERN LHC. The paper focuses on prompt isolated electrons with transverse momenta ranging from about 5 to a few 100 GeV. A detailed description is given of the algorithms used to cluster energy in the electromagnetic calorimeter and to reconstruct electron trajectories in the tracker. The electron momentum is estimated by combining the energy measurement in the calorimeter with the momentum measurement in the tracker. Benchmark selection criteria are presented, and their performances assessed using Z, Upsilon, and J/psi decays into electron-positron pairs. The spectra of the observables relevant to electron reconstruction and selection as well as their global efficiencies are well reproduced by Monte Carlo simulations. The momentum scale is calibrated with an uncertainty smaller than 0.3%. The momentum resolution for electrons produced in Z boson decays ranges from 1.7 to 4.5%, depending on electron pseudorapidity and energy loss through bremsstrahlung in the detector material.