Status Update

1
Status Update

• Lindsey Gray
• University of Wisconsin at Madison
• Weekly Meeting
• 15 July, 2009

2
Action Items

• Pythia/MadGraph Analysis
• Produce plots from PAT2 with more background
  samples
• To be shown, with all kinematics cuts first.
• First results of multivariate analysis
• On hold till I figure out how to access the
  necessary variables with PAT
• Status of POWHEG adaptation of Baurs MC
  Generator
• Trying to figure out singularities in Baurs
  cross section
• Check POWHEG against Tevatron data (almost
  there!)
• Resurrect and show plots from RCT Calibration
  Routines
• Postponed until Fall

3
Z? Analysis
4
Status Summary

• Since last week
• Modified analyzer to use patPhoton
• Eliminates need for PhotonIDAssociationMap
• Still hunting for the necessary cluster shape
  variables for Mikes Fisher discriminator
• Reordered cuts
• Lepton isolation -gt Kinematics Cuts -gt Photon
  Isolation
• Now able to relax some cuts, gain in significance
  for SM signal
• EM enriched QCD samples now available
• Running on those later today

5
Preselection Requirements

• 1 dilepton pair within 60GeV of Z mass
• µ or e pairs
• A reconstructed photon
• No ID
• All particles within tracker volume

Event Yields Z? 160 ZJets 28k WJets
12k TTbarJets 8k Mu-QCD 880M
200pb-1
6
Selecting Leptons for Z Reconstruction

• Introduction of QCD sample contains large
  background from fake µ e
• Even after photon selection!
• No real lepton selection in original analysis
• Just Zjets at that point, wasnt really needed
• Removed by using lepton isolation scaled by pT lt
  .3
• Must be replaced by standard lepton IDs (need to
  modify tree)

Event Yields Z? 150 ZJets 23k WJets
830 TTbarJets 630 Mu-QCD 15M
reject
7
Selecting Dileptons for Z? Reconstruction

• Cut on dilepton mass
• 70 GeV lt M lt 100 GeV

Event Yields Z? 130 ZJets 19k WJets
140 TTbarJets 190 Mu-QCD 970k
8
Selecting Outer Z? Photons

• Photons from Outer Z? are more often further away
  from lepton pair.
• Cut relaxed
• Old ?R gt 1.3
• New ?R gt .7

Event Yields Z? 120 ZJets 18k WJets
140 TTbarJets 190 Mu-QCD 950k
9
Selecting Outer Z? Events

• Require MZ? gt 105 GeV

Event Yields Z? 100 ZJets 15k WJets
40 TTbarJets 130 Mu-QCD 220k
10
Selecting Isolated Photons H/E

• First apply H/E Cut
• Require H/E lt .025

Event Yields Z? 100 ZJets 5.5k WJets
9.6 TTbarJets 22 Mu-QCD 0
reject
11
Selecting Isolated Photons r9

• Require r9 gt .9

Event Yields Z? 69 ZJets 710 WJets
1.6 TTbarJets 2.4 Mu-QCD 0
reject
12
Selecting Isolated Photons Track Isolation

• Require number of tracks in a solid cone lt 3

reject
Event Yields Z? 64 ZJets 240 WJets
0 TTbarJets 1 Mu-QCD 0
13
Selecting Isolated PhotonsPhoton Isolation

• Require
• Sum Isol/Pt lt .45

reject
Event Yields Z? 51 ZJets 74 WJets
0 TTbarJets .5 Mu-QCD 0
14
Selecting Isolated PhotonsPhi Width

• Final Cut
• Require
• Phi Width lt .02

reject
Event Yields Z? 43 ZJets 51 WJets
0 TTbarJets .5 Mu-QCD 0
15
Final Results
Final Event Yields Z? 43 ZJets 51 WJets
0 TTbarJets .5 Mu-QCD 0
Significance 4.42 s
16
Next Steps

• For Analysis
• Update analyzer to access variables, through PAT,
  for standard lepton isolation cuts.
• Optimize each cut for S/sqrt(SB)
• Get e5x5, e2x5, e3x3, Zernike Moments from PAT
  photon for Multivariate Analysis
• If possible?
• For POWHEG
• Fully understand singularity structure in Z?1
  Jet cross section
• Begin work on Muon DPG Digi Validation