DWPhysicsAnalysis

Welcome to my analysis issues page. Here I've posted some of the issues I'm looking at and some of the questions I have. Feel free to leave comments if you have any.

High-pT (or high-Sum-ET) top/anti-top identification and reconstruction

I'm looking to understand various issues of triggering and reconstruction performance in high-pT t-tbar production, working in Athena version 14. I'm focusing right now on the semi-leptonic (electron) decay mode, t t -> b e nu, b q q.

Right now I've been trying to compare the trigger and reco performance in version 14 with what was reported in the ATLAS CSC NOTE "Top quark physics at ATLAS" (using version 12).

Datasets

I've taken official evgen datasets and re-simulated, re-digitized, and re-reconstructed them in version 14 of Athena. I ended up using a couple of the AtlasTier0-14.2.10.Y releases, since those were collections of tags that I could find in 14.2.10.Y that would actually complete the simulation/digitization/reconstruction tasks, though I'm open to re-running these datasets in the version used for official production (whenever that is up and running).
  • ~28,000 SM t-tbar events from 5200 evgen dataset
  • ~20,000 1 TeV Z' t-tbar events from 6231 evgen dataset
  • Simulation & Digitization performed with AtlasTier0-14.2.10.2
  • Reconstruction (AOD) performed with AtlasTier0-14.2.10.8

Monte-Carlo-level Event Acceptance Cuts

  • Only t -> b W, W -> q q & t -> b W, W -> e nu events accepted, based on MC truth
  • Detector acceptance cuts applied on b q q b e nu
    • Electron: |η| < 2.5, with 1.37 < |η| < 1.52 excluded (calorimeter crack veto)
    • b-quarks, quarks from W: |η| < 2.5

Commissioning Object Selection

I've attempted to make object selections which are as close as possible to those described in the Top CSC note.
  • Electron (ElectronAODCollection)
    • IsEM = ElectronMedium
    • |η| < 2.5 with 1.37 < |η| < 1.52 excluded (calorimeter crack veto)
    • Calorimeter ET in cone (ΔR = 0.2) < 6 GeV
  • Muon (StacoMuonCollection)
    • |η| < 2.5
    • Calorimeter ET in cone (ΔR = 0.2) < 6 GeV
  • Jet (Kt4LCTopoJets)

-- DenverWhittington - 03 Sep 2008

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Topic revision: r1 - 2008-09-03 - DenverWhittington
 
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