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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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4 4Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

Jets

pT distribution

Jets using 0.7 cone with preliminary Run II corrections

Dijet invariant mass

Alexander Kupco, Prague

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5 5Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

Jets - NADA and Missing ET

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6 6Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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7 7Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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8 8Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

Electrons – energy scale

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9 9Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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10 10Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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11 11Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

Electrons – the W – data

data - bkgBack to back jetLow missing Et

Fit = [Signal+(1-)Bckg]

We MC

data

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12 12Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

Electrons – the W – mT

Fit = [Signal+(1-)Bckg]

mT(e,) L~0.7pb-1

(uncalibrated energy scale)

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13 13Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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14 14Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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15 15Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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16 16Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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17 17Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

b tagging – Impact Parameter

MC

D. Wijngaarden, F. Fithaut

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18 18Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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19 19Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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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20 20Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

Taus – Variables and background

The Jet Width –‘s are narrow jets

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21 21Silke Duensing DØ Analysis Status NIKHEF Annual Scientific Meeting 2001

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