1 silke duensing dØ analysis status nikhef annual scientific meeting 2001 1 analysing first d0 data...
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1 1Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001
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
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2 2Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001
Using R=0.7 Cone Algorithm with Run 1 corrections
2-jet event• ET
jet1~230GeV• ET
jet2~190GeV
3-jet event• ET
jet1~310GeV• ET
jet2~240GeV• ET
jet3~110GeV• ET~8GeV
Real data - Jets
Red: EM towers
Blue: Had towers
: -log(/2)
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3 3Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001
Jets – cone algorithm
Ex: Improved Legacy
• Simple cone preclustering (seeds)
collect energy in cone Midpoint seeds added in
for each pair of jets within R < R < 2R
Jet axis recalculated until stable
geometric centre = enery centriod
Splitting and merging after all stable protojets have been found
seeds midpoints
approximates seedless algorithm
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Jets
pT distribution
Jets using 0.7 cone with preliminary Run II corrections
Dijet invariant mass
Alexander Kupco, Prague
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Jets - NADA and Missing ET
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Ia Iashvili, Riverside
DØ
jet
DØ
DØ
E' = ETxcosh(jet)
Jets – Energy scale
Response in the central calorimeter
EM fraction = 0.48ET
Jet=24GeV
EM fraction >0.9Isolation < 0.2
ETJet=27GeV
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Electrons – the Z
2 EM objects, ET > 20 GeV,isolation and shower shape cuts
(uncalibrated energy scale)Leo Chan, Rochester
e e
L~1.2pb-1
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Electrons – energy scale
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Electrons – trigger
L1:
Frank Filthaut Jet ET
EM clusters, pT > 10 GeVIsolated, EM fraction > 0.9
|| < 1.1
failed (prescaled)
pass
Volker Buescher, Mainz
L3:
failed (prescaled)
pass
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Electrons – the W
EM clusterwith track
Vishnu Zutshi, NIULeo Chan, Rochester
e
ET
Kinematics:
pT >22.5 GeV, | <0.6
Shower characteristics:
EM fraction (0.95<emf<1.05)
Isolation (-0.05<iso<0.1)
widths, H-Matrix
Event characteristics:
Large Missing ET (>25 GeV)
No back-to-back jet,
roughly back-to-back MET
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Electrons – the W – data
data - bkgBack to back jetLow missing Et
Fit = [Signal+(1-)Bckg]
We MC
data
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Electrons – the W – mT
Fit = [Signal+(1-)Bckg]
mT(e,) L~0.7pb-1
(uncalibrated energy scale)
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Muons observed - in Jets
Muon in jet (b candidate)Hits in A,B,C layers
Onne Peters, NIKHEF
Back to backcalorimeter jets
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Muons - J/
id: Require wire hits in B/C
layer Require hits in A + B/C
scintillators
Frederic Deliot, Saclay
Events: 6846 events from
5.8 M pre-shutdown events
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Muons – b cross section vs pT
Data Sample 3.2 M data events Total exposed
luminosity: 750 nb-1
Events passing L1 +jet trigger: 800k
· Require 1 jet + 1 |njet| < 0.6, |n| < 0.8 pT > 6 GeV, dR (, jet) < 0.7
Run 1 Integrated Cross SectionJet pT > 20 GeV: 12.9 nbJet pT > 30 GeV: 4.27 nb Run 2 Integrated Cross SectionJet pT > 20 GeV: 9.31 nb (39% low)Jet pT > 30 GeV: 2.77 nb (54% low)
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Muons – b tagging
Fit -> signal fraction 65%,
Fit error 10%
PTRel
Ejet
p
Run II data
Run I BG templ
Run I Signal templ
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b tagging – Impact Parameter
MC
D. Wijngaarden, F. Fithaut
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Tracking – KS
Combination of oppositely charged tracksAfter cuts on de/dx and the decays length After cuts on DCA and decay*momentum vector Requiring KS pT between 0.4-7 & 2 < 10
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Taus – decays and reconstruction
Cluster with simple cone algorithm,
cone 0.3 + 0.5 in
ee 17.8 %
17.4 %
48 %
15.2 %
‘s are narrow jets
SMT ECAL HCAL CFT
and: ’s have 1 or 3 tracks with the right invariant mass or Ecal/Etrack
but: not yet
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Taus – Variables and background
The Jet Width –‘s are narrow jets
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Outlook and status - MoriondPhysics: W/Z:
in electrons and muons, Z’ to ee
QCD: jet pT spectrum+dijets
B: KS, J/ B tag with and IP,SV
Higgs, top: W/Z plus jets
Tools: Energy scale:
in electrons for jets: with /jet
Comparison with MC Trigger commissioning ID – cuts, efficiencies