Analysing first D0 data

1
Analysing first D0 data

• Real Data with
• Jets
• Missing Et
• Electrons
• Muons
• Taus
• And from there up to
• Electroweak Bosons W/Z
• B cross section
• And then top, Higgs,

• Silke Duensing, KU Nijmegen

2
Real data - Jets
Using R0.7 Cone Algorithm with Run 1 corrections

• 3-jet event
• ETjet1310GeV
• ETjet2240GeV
• ETjet3110GeV
• ET8GeV

h
f
Red EM towers Blue Had towers h -log(q/2)

• 2-jet event
• ETjet1230GeV
• ETjet2190GeV

h
f
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Jets cone algorithm

• Ex Improved Legacy
• Simple cone preclustering (?seeds)
• collect energy in h-q cone
• Midpoint seeds added in for each pair of jets
  within R lt DR lt 2R
• Jet axis recalculated until stable
• geometric centre enery centriod
• Splitting and merging after all stable protojets
  have been found

midpoints
seeds
approximates seedless algorithm
4
Jets

• pT distribution
• Jets using 0.7 cone with preliminary Run II
  corrections

• Dijet invariant mass
• Alexander Kupco, Prague

5
Jets - NADA and Missing ET
6
Jets Energy scale
Response in the central calorimeter
?
jet
DØ
DØ
DØ
ETJet27GeV
EM fraction gt0.9
Isolation lt 0.2
ETJet24GeV
EM fraction 0.48
E' ETg x cosh(hjet)
Ia Iashvili, Riverside
7
Electrons the Z
2 EM objects, ET gt 20 GeV, isolation and shower
shape cuts
L1.2pb-1
e
e
Leo Chan, Rochester
(uncalibrated energy scale)
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Electrons energy scale
9
Electrons trigger
EM clusters, pT gt 10 GeV Isolated, EM fraction gt
0.9 ? lt 1.1 failed (prescaled) pass
Volker Buescher, Mainz L3
failed (prescaled) pass
Frank Filthaut Jet ET

• L1

10
Electrons the W

• Kinematics
• pT gt22.5 GeV, h lt0.6
• Shower characteristics
• EM fraction (0.95ltemflt1.05)
• Isolation (-0.05ltisolt0.1)
• h-f widths, H-Matrix
• Event characteristics
• Large Missing ET (gt25 GeV)
• No back-to-back jet,
• roughly back-to-back MET

Vishnu Zutshi, NIU Leo Chan, Rochester
EM cluster with track
ET
e
11
Electrons the W data
data
data - bkg
Back to back jet Low missing Et
W?e MC
Fit abSignal(1-b)Bckg
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Electrons the W mT
mT(e,n) L0.7pb-1 (uncalibrated energy scale)
Fit abSignal(1-b)Bckg
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Muons observed - in Jets
Onne Peters, NIKHEF
Back to back calorimeter jets
Muon in jet (b candidate) Hits in A,B,C layers
14
Muons - J/?

• Events
• 6846 events from 5.8 M pre-shutdown events

• m id
• Require wire hits in B/C layer
• Require hits in A B/C scintillators
• Frederic Deliot, Saclay

15
Muons b cross section vs pT

• Data Sample 
• 3.2 M data events
• Total exposed luminosity 750 nb-1
• Events passing L1 mjet trigger 800k
•  Require ?1 jet ?1 m
• njet lt 0.6, nm lt 0.8
• pTm gt 6 GeV, dR (m, jet) lt 0.7

Run 1 Integrated Cross Section Jet pT gt 20 GeV
12.9 nb Jet pT gt 30 GeV 4.27 nb   Run 2
Integrated Cross Section Jet pT gt 20 GeV 9.31 nb
(39 low) Jet pT gt 30 GeV 2.77 nb (54 low)

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Muons b tagging
Run II data
Run I BG templ
Run I Signal templ

• Fit -gt signal fraction 65,
• Fit error 10

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b tagging Impact Parameter
MC
D. Wijngaarden, F. Fithaut
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Tracking KS
Requiring KS pT between 0.4-7 c2 lt 10

Combination of oppositely charged tracks
After cuts on de/dx and the decays length
After cuts on DCA and decaymomentum vector
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Taus decays and reconstruction
SMT ECAL HCAL m
CFT

• Cluster with simple cone algorithm,
• cone 0.3 0.5 in hf

and ts have 1 or 3 tracks with the right
invariant mass or Ecal/Etrack but not yet

• ts are narrow jets

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Taus Variables and background

• The Jet Width
• ts are narrow jets

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Outlook and status - Moriond

• Physics
• W/Z
• in electrons and muons, Z to ee
• QCD
• jet pT spectrumdijets
• B
• KS, J/Y
• B tag with m and IP,SV
• Higgs, top
• W/Z plus jets

• Tools
• Energy scale
• in electrons
• for jets with g/jet
• Comparison with MC
• Trigger commissioning
• ID cuts, efficiencies