The European Physical Journal C

, Volume 49, Issue 4, pp 1099–1116

Electron reconstruction in CMS

Authors

  • S. Baffioni
    • Laboratoire Leprince-RinguetEcole Polytechnique and IN2P3-CNRS
  • C. Charlot
    • Laboratoire Leprince-RinguetEcole Polytechnique and IN2P3-CNRS
  • F. Ferri
    • Laboratoire Leprince-RinguetEcole Polytechnique and IN2P3-CNRS
    • Università degli Studi Milano-Bicocca and INFN-Sezione di Milano
  • D. Futyan
    • University of California
  • P. Meridiani
    • Dipartimento di Fisica and INFN-Sezione di RomaUniversità “La Sapienza”
    • FESBTechnical University of Split
  • C. Rovelli
    • Laboratoire Leprince-RinguetEcole Polytechnique and IN2P3-CNRS
    • Università degli Studi Milano-Bicocca and INFN-Sezione di Milano
  • R. Salerno
    • Laboratoire Leprince-RinguetEcole Polytechnique and IN2P3-CNRS
    • Università degli Studi Milano-Bicocca and INFN-Sezione di Milano
  • Y. Sirois
    • Laboratoire Leprince-RinguetEcole Polytechnique and IN2P3-CNRS
Special Article - Scientific Note

DOI: 10.1140/epjc/s10052-006-0175-5

Cite this article as:
Baffioni, S., Charlot, C., Ferri, F. et al. Eur. Phys. J. C (2007) 49: 1099. doi:10.1140/epjc/s10052-006-0175-5

Abstract

The reconstruction of the energy and momentum of isolated electrons in CMS combining tracking and electromagnetic calorimetry information is described. The emphasis is put on primary electrons with transverse momentum below 50 GeV/c. The energy deposited in the electromagnetic calorimeter is measured in clusters of clusters (superclusters) which collect bremsstrahlung photons emitted along the electron trajectory in the tracker volume. The electron tracks are built from seeds in the pixel detector found via a cluster-driven pixel hit matching algorithm, followed by a reconstruction of trajectories in the silicon strip tracker with a Gaussian sum filter. Electrons are classified using observables sensitive to the pattern of bremsstrahlung emission and electromagnetic showering in the tracker material. Energy scale corrections depending on the electron class are applied to the supercluster and estimates of associated errors are obtained. The electron energy is deduced from a weighted combination of the corrected supercluster energy and tracker momentum measurements. The electron direction is that of the reconstructed electron track at interaction vertex. The pre-selection of isolated electron candidates for physics analysis is described. Class-dependent observables combining tracking and calorimetry information are discussed for electron identification.

Copyright information

© Springer-Verlag Berlin Heidelberg 2007