b-jet cross section measurement

1
B-jet cross section measurement

• Data sample
• Physics distributions of real data sample
• ? jet cross section measurement
• PTRel templates fits
• B-jet content measurement
• B-jet cross section measurement

2
Data sample - real

• Real data sample
• Runs 149270 152212
• Removed bad muon jet runs
• mu1ptxatxx_CJT5 trigger requirement
• Select ?jet events (0.7 cone)
• Total number of events 20502
• Total integrated luminosity 0.6 pb-1

3
Data sample - MC

• bbbar17k events, p10.08.01
• QCD
• 1M p10.11.00 events
• 165k p10.15.01 events (? lt 2)
• Currently huge statistics needed need hack!
• Extract all non-b background from QCD (?/K??,
  c??, b?c??)

4
Data Selection (cuts)

• Muon
• gt 2 A-layer hits
• gt 3 BC-layer hits
• gt 0 A-layer scint hits
• gt 0 B-layer scint hits
• ?2 gt 0 (converged fit)

• Jet
• CHF lt 0.4
• HotF lt 10
• 0.05 lt EMF lt 0.95
• n90 gt 1

?R( ?, jet) lt 0.7 mu1atxctxx_CJT5 trigger
Accept
5
Physics properties
6
? jet cross section (1)
Efficiencies
L1 muon L1 jet Geom. Acc. Muon recoID Jet RecoID
0.40 1.0 (gt20 GeV) 0.89 0.47 0.98
?R(?, jet) lt 0.7 pT? gt 6 GeV/c ?? lt 0.8
?jet lt 0.6
Muon ID version v1.1 Jet Certification v1.2 DØ
note 3949
7
? jet cross section (2)
Limited statistics in MC data ? Looser cuts
?R(?, jet) lt 0.7 pT? gt 3 GeV/c ?? lt 1 ?jet
lt 1
Note lower 2 lines use tight cuts
8
PTRel Data MC
?R(?, jet) lt 0.7 pT? gt 3 GeV/c ?? lt 1 ?jet
lt 1
9
PTRel Fits
20 lt Ptjet lt 30 GeV
b-jet content 31.9 ? 4.8
Ptjet gt 30 GeV
b-jet content 17 ? 6.6
10
B-jet content
11
B-jet cross section
Note Run I data uses tight cuts
12
Conclusions

• MC statistics remains a problem
• Currently generating, but need better solution
• Data statistics low (but available)
• Current results are looking promising