First look at SvS B

1
First look at S/v(SB)
MC samples used for this first study
2
More samples
Other MC samples are being generated
3
Approach

• Follow D0s approach
• Ask for 1 tight muon (high pt requirements) and 1
  loose muon (low pt requirements)
• Add a third muon (very loose muon, low pt
  requirements with pt gt3 GeV)
• We investigate 3 pt scenarios
• Tight muon, ptgt20 GeV and loose muon
• a. Pt gt 20 GeV
• b. Pt gt 10 GeV
• c. Pt gt 5 GeV

The cut optimization is performed as for now
in scenario (c).
4
Muon quality criteria

• Loose tight muon
• Pt gt 4 GeV 20 GeV
• Has CMU CMP CMX stub
• NCOTSegments gt 2 with gt5 Hits gt7 Hits
• Energy Em lt 1 GeV Had lt 4 Gev (EmHad) gt
  0.1 GeV
• Energy Em lt 2 max(0,(p-100)0.0115) GeV
• Had lt 6 max(0,(p-100)0.028)
  Gev (EmHad) gt 0.1 GeV
• d0 lt 0.2 cm
• Stub Dx lt 3 cm for CMU Chi2lt9,
• 5 cm for CMP Chi2lt9,
• 6 cm for CMX Chi2lt9
• Stub Dx lt 3 cm for CMU, 5 cm for CMP, 6 cm for
  CMX
• Calorimeter Iso lt 0.1
• Track Chi2/(n COT hits -5) lt 3

5
Muon and MET content
Third muon or track requirement helps in S/B Use
that as last cut increase acceptance
Not corrected for muons yet
Run I D0 (e? and ?? LS) METgt 15 GeV
6
Pt distributions
D0 (e? and ?? LS) pTgt 8/5 GeV Our approach pT
gt 20/10/4 GeV
D0 (e? and ?? LS) pTgt 12/11 GeV Our approach
pT gt 20 GeV
7
Eta distributions
As for now, central only ? lt 1
8
Invariant Mass distribution
D0 (e? and ?? LS) 15 lt Me? lt 100 GeV LS M ??
lt 80 GeV OS M ?? lt 70 GeV M ?? gt 110
GeV Our approach 15 lt M?? lt 60 GeV
9
Significance
SignificanceMET/Sumet SumEt usefull in removing
the t-tbar contamination
10
Geometrical distributions
D0 (?? LS) Df ?? lt 140º Our approach Df ??
lt 160º
D0 (?? LS) Df ?Met mingt 30º
D0 (?? LS) Df ?Met maxlt 140º
11
Jet content (I)
n. Of jets in the event with Etgt 15/50/80 GeV
Either veto jets or jet requirements
12
Jet content (II)
D0 (?? LS) Df lt 140º
13
Next

• Extend study to all backgrounds
• Optimize cuts
• Look for the best variables to distinguish signal
  from background
• Eventually, change the approach