Missing ET Reconstruction in ATHENA Using Reconstructed Objects

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Missing ET Reconstruction in ATHENA Using
Reconstructed Objects

• Bryan Caron (Jim Pinfold)
• University of Alberta

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Calculating Etmiss Using Reconstructed Objects

• Calculate Etmiss using reconstructed objects.
• Introduce new additional TOP Level Algorithm
  MissingETRecObjectBuilder
• Access contents of reconstructed object
  containers for e/gamma, Jets (Kt cone), Taus,
  EG egammaContainer, etc.
• For now keep to existing calorimeter objects
• Expand to include muon information, etc.
• Use the structure of other reconstruction
  packages ( egammaREec, tauRec) as a foundation

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Calibration Using Reconstructed Objects

• Four basic kinds of reconstructed objects will be
  used e/gamma, jets (Kt Cone), taus, muons.
• Next look at cells outside of the reconstructed
  objects and study their origin, eg
• Tails from reconstructed objects?
• Isolated MIPs, track-able from the ID (using
  energy flow)? Etc?
• Expand the definition of reconstructed object
  (e/g, jet,t,m) for Etmiss calibration, if
  necessary.

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Looking at Cells Outside of Reconstructed Objects

• Define optimal method to ID cells outside of
  clusters
• Calibrate cells outside of reconstructed
  objects (or redefined reconstructed objects)
  using Minimum Bias events.

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Where are we now?

• Currently debugging creation of the new TOP LEVEL
  algorithm and methods of access to reconstructed
  object containers.
• The method we are following is complementary to
  the approach of Donatella and SylviaBUT longer
  term
• Perform calibration by minimizing missing energy
  resolution using as elements the energy of the
  reconstructed objects plus those cells NOT in the
  reconstructed objects.

Where are we going