Track Quality Study

Various kinematical variables of reconstructed tracks Tracks.

No Cuts (RecoTrack)

I loop over all reconstructed tracks in an event and plot the following kinematical variables and detector information: P_T, η, φ, d₀, z₀, and the number of valid hits in the tracker.

• ~50k Z→μμ events. (pdf version)
  
  

• ~120k QCD (50 < P_T < 80) events. RawVariablesQCD50to80.pdf

Matched vs Unmatched.

In each event I have two loops:

• The first loop is over the RecoTracks in each event. Next I define a match as a RecoTrack that has a corresponding SimTrack associated by hits using CMSSW_1_3_1 TrackAssociatorByHits that Boris showed me. Unmatched is defined as NOT Matched.
  • ~50k Z→μμ events: (pdf version)
    
    
    
  • Same plot as above but each distribution is normalized to one.
    
    

• The Second loop is over the SimTracks in each event. Next I define a match as a SimTrack that has a corresponding RecoTrack associated by hits again using CMSSW_1_3_1 TrackAssociatorByHits. Unmatched is defined as NOT Matched.
  • ~50k Z→μμ events: (pdf version)
    
    
  • ~120k QCD (50 < P_T < 80) events:
    
    

With Cuts

• The following cuts were applied:
  
  • |η| < 2.5
  • # valid hits > 7
  • |d₀| < 1 mm
  • |z₀| < 30 cm
  • χ²/d.o.f. < 10

• RecoTracks that have an associated SimTrack.
  • ~50k Z→μμ events: cutsMatchedReco.pdf
    
    

• RecoTracks that do NOT have an associated SimTrack.
  • ~50k Z→μμ events: cutsNotMatchedReco.pdf
    
    

A closer look at the effect of these cuts. ~50k Z→μμ events:

• RecoTracks that are matched with p_T > 15.0 GeV
  
  
• RecoTracks that are NOT matched with p_T > 15.0 GeV
  
  
• RecoTracks that are matched with 1.0 GeV < p_T < 5.0 GeV
  
  
• RecoTracks that are NOT matched with 1.0 GeV < p_T < 5.0 GeV
  
  

Same plots as above but on ~120k QCD 50 to 80 GeV in PT events:

• RecoTracks that are matched with p_T > 15.0 GeV
  
  
• RecoTracks that are NOT matched with p_T > 15.0 GeV
  
  
• RecoTracks that are matched with 1.0 GeV < p_T < 5.0 GeV
  
  
• RecoTracks that are NOT matched with 1.0 GeV < p_T < 5.0 GeV
  
  

Ratio of with quality cuts to without.

• Ratio of RecoTracks (matched) with quality cuts to RecoTracks without quality cuts:
  • ~50k Z→μμ events:
    
    
  • Same plots as above but on ~120k QCD (50 < P_T < 80) events:
    
    

Δ = Reco - Sim.

• Calculated the difference between RecoTrack and SimTrack variables.
  • ~50k Z→μμ events:
    
    
  • ~120k QCD (50 < P_T < 80) events:
    
    

Pull Distributions

• Pull = ΔVariable / VariableError.
  • ~50k Z→μμ events:
    
    
  • ~50k Z→μμ events (Log plots):
    
    
• ~120k QCD (50 < P_T < 80) events. Pullqcd_50_80_120k.pdf

-- RyanKelley - 14 Aug 2007