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.
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References
R. Frühwirth, Comput. Phys. Commun. 100, 1 (1997)
W. Adam, R. Frühwirth, A. Strandlie, T. Todorov, Reconstruction of Electrons with the Gaussian-Sum Filter in the CMS Tracker at the LHC, CMS Note 2005/001 (January 2005) pp. 11
ORCA, Object-oriented Reconstruction for CMS Analysis, version 8.7.3. (February 2005)
CMS Collaboration, The Compact Muon Solenoid – Technical Proposal, CERN/LHCC 94-38 (December 1994) pp. 290
CMS Collaboration, The Tracker Project – Technical Design Report, CERN/LHCC 98-6 (April 1998) pp. 625; CMS Collaboration, Addendum to the Tracker TDR, CERN/LHCC 2000-016 (February 2000) pp. 82
CMS Collaboration, The Electromagnetic Calorimeter Project – Technical Design Report, CERN/LHCC 97-23 (15 December 1998) pp. 364
S. Cucciarelli, M. Konecki, D. Kotlinski, T. Todorov, Track Reconstruction, Primary Vertex Finding and Seed Generation with the Pixel Detector, CMS NOTE-2006/026 (January 2006) pp. 22
D. Abbaneo, Layout and Performance of the CMS Silicon Strip Tracker, Talk given at the 9th Pisa meeting on Advanced Detector, La Biodola, Isola d’Elba, Italy (May 25–31) 2003
CMS Collaboration, CMS Physics Technical Design Report Vol. 1, CERN/LHCC 2006-001 (February 2006) pp. 547
CMS Collaboration, The Trigger and Data Acquisition Project, Vol. 1, CERN/LHCC 2000-038 (December 2000) pp. 599
E. Meschi, T. Monteiro, C. Seez, P. Vikas, Electron Reconstruction in the CMS Electromagnetic Calorimeter, CMS Note 2001/034 (June 2001) pp. 16
F. Ferri, The CMS Electromagnetic Calorimeter for the Higgs Boson Search H→ZZ(*)→4e± at the LHC, Doctor degree thesis, University of Milano-Bicocca (Italy) and Ecole Polytechnique (France) (December 2005) pp. 170
P. Meridiani, R. Paramatti, Use of Z→e+e- events for ECAL calibration, CMS NOTE-2006/039 (January 2006) pp. 18
S. Baffioni et al., J. Phys. G: Nucl. Part. Phys. 34, N23 (2007)
P. Meridiani, Optimization of the discovery potential of the Higgs Boson in the decay channel H→ZZ(*)→4e± with the CMS detector, Doctor degree thesis, University of Roma-1 (September 2004) pp. 199
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Baffioni, S., Charlot, C., Ferri, F. et al. Electron reconstruction in CMS. Eur. Phys. J. C 49, 1099–1116 (2007). https://doi.org/10.1140/epjc/s10052-006-0175-5
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DOI: https://doi.org/10.1140/epjc/s10052-006-0175-5