Studies of Electron Charge Misidentification by other people

• compare monoclusters/multiclusters
  • 1 cluster: simple electron
  • 2 clusters: electron + photon
  • >2 clusters: more complication
• studies at pT = 35 GeV (RelVal sample, what a surprise) http://indico.cern.ch/materialDisplay.py?contribId=3&materialId=slides&confId=50970
  • curvature of track: 2.5% misidentification
  • delta phi between seed and supercluster barycenter: take sign relative to axis:
    • axis: seed tangent at vertex: 2.14% misidentification
    • axis: beamspot -> first hit on electron track: 1.69% misidentification
  • direction of P_out: extrapolate last hit to ecal, take sign of φ_ext - φ_out: 4.74% misidentification
    • only for mono clusters: 1.76% misidentification
    • only for multi clusters: 7.44% misidentification
    • very track purity dependent
  • for monocluster, combine correlated to fBrem:
    • take standard (1.75% misidentification) for fBrem < 0.34
    • take supercluster 2 (0.86%) for fBrem > 0.34
    • combined 0.69% misidentification
  • charge significance method (not clear what this is)
  • ideas for new methods for multicluster electrons based on:
    • comparison of different clusters
    • position of the cluster of initial electron wrt to the other sub clusters
• data driven method for electron-charge misidentification http://indico.cern.ch/materialDisplay.py?contribId=0&materialId=slides&confId=52580
  • most interesting variables used in TMVA methods (amongst others)
    • skewness of supercluster hits in φ, very sensitive to fBrem
      • not very discriminating on its own, weight with exp(1/fBrem)
    • φ_innermost-φ_seed
• Measurement of wrong charge reconstruction probability of electrons from data http://indico.cern.ch/materialDisplay.py?contribId=2&materialId=slides&confId=53366
  • interesting

Update 090719

• Boris Mangano: "Recent investigations on electron charge mis-measurement" http://indico.cern.ch/getFile.py/access?contribId=3&resId=1&materialId=slides&confId=44569
  • 2 reasons why tracking does not reconstruct the electron but rather one of the conversion legs
    • SeedCleaning : already used seed is not retried so the prompt electron is missed
    • TrajectoryCleaning : hit sharing >= 50%, shorter track or track with higher chi2/ndof is discarded
• Broutin http://indico.cern.ch/getFile.py/access?contribId=0&resId=0&materialId=slides&confId=62527
  • old methods from above
  • majority method:
    1. if q_in agrees with q_out, ok
    2. if not, supercluster method: delta phi between seed and supercluster barycenter: take sign relative to axis:

variables to look at

• sign of delta phi between super cluster barycenter and seed relative to axis beamspot-first hit on electron track
• modified skewness