Meenakshi Narain, ICHEP2002, 7/29/2002 Results from the Results from the Dzero Dzero Experiment at the Experiment at the Tevatron Tevatron Meenakshi Narain Boston University Representing the Dzero Collaboration XXXI International Conference on High Energy Physics (ICHEP2002), Amsterdam, The Netherlands
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Results from the Dzero Experiment at the Tevatron · Meenakshi Narain, ICHEP2002, 7/29/2002 DØ. in . RunII • Center of Mass Energy = 1.96 TeV • Expect 2 fb-1. by end of 2004
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Meenakshi Narain, ICHEP2002, 7/29/2002
Results from the Results from the DzeroDzero Experiment at the Experiment at the TevatronTevatron
Meenakshi NarainBoston University
Representing the Dzero Collaboration
XXXI International Conference on High Energy Physics (ICHEP2002), Amsterdam, The Netherlands
Meenakshi Narain, ICHEP2002, 7/29/2002
DDØØ in in RunIIRunII
• Center of Mass Energy = 1.96 TeV• Expect 2 fb-1 by end of 2004 (RunIIa),
15 fb-1 by 2008 (RunIIb)• Goals
– Comprehensive study of top quark properties– Precise measurements of mtop, mW, AFB
– Search for new phenomena (SUSY, technicolor,…)– Search for the Higgs boson– QCD (proton structure, quark compositeness)– B-physics (Bs mixing)
• DØ’s strength is high-pT physics• Requires
– Measurement of leptons (e, µ), jets, missing pT
– Flavor tagging of jets
Meenakshi Narain, ICHEP2002, 7/29/2002
Main Injector& Recycler
Tevatron
Chicago↓
p source
Booster
p
p CDF
DØDØ
DØ
• pp collisions• Ecom = 1.96 TeV• 396 ns bunch spacing• Run II peak luminosity
now: 2.1×1031 cm-2s-1
goal: 8.6×1031 cm-2s-1
• pp collisions• Ecom = 1.96 TeV• 396 ns bunch spacing• Run II peak luminosity
Charge correlation between p and n-side of a silicon detector
Hit efficiencies >97%
Meenakshi Narain, ICHEP2002, 7/29/2002
pT GeV
track
x
width = 36 µmσ(beam) = 30 µm
σ = 20 µm
width = 36 µmσ(beam) = 30 µm
σ = 20 µm
Impact parameter
Detector PerformanceDetector Performance y
• Impact Parameter Resolution
Survey-only alignment constants
significant improvement expected from alignment with data in near future
Meenakshi Narain, ICHEP2002, 7/29/2002
Detector PerformanceDetector Performance
• Fiber Tracker
light yield vs pseudorapidity η
Hit efficiency ¼ 98%
Ks0! π+π-
All tracking detectors working as expected
Z→ee candidateMass 89.9GeV/c2
Meenakshi Narain, ICHEP2002, 7/29/2002
Detector PerformanceDetector Performance
0 10 20 30 40 50 60 70 80 90 100
10-1
1
10
Missing Transverse Energy, GeV
J/ψ and ψ’• Muons
• Electrons
E/P0 0.5 1 1.5 2 2.5 3
Eve
nts
/ 0.
05
0
50
100
150
200
250Chi2 / ndf = 0.5317 / 4
156.4 ±p0 = 105.6
490.4 ±p1 = -411.3
459.2 ±p2 = 530.6
141.7 ±p3 = -192.2
26.31 ±N = 147.6
0.01741 ±Mean = 1.031
0.02659 ±Sigma = 0.165
DØ Run 2 Preliminary
candidate eventsν e→W
>20 GeVmissT>20 GeV, Eel
TP
E/P Chi2 / ndf = 0.5317 / 4
156.4 ±p0 = 105.6
490.4 ±p1 = -411.3
459.2 ±p2 = 530.6
141.7 ±p3 = -192.2
26.31 ±N = 147.6
0.01741 ±Mean = 1.031
0.02659 ±Sigma = 0.165
W! eν
Z→µµ
DØ Run 2 Preliminary
• Missing ET
Detector performanceconsistent with expectations!
Di-photon Data
Multijet data
Meenakshi Narain, ICHEP2002, 7/29/2002
IdentyfyingIdentyfying bb--quarksquarks• Signed impact parameter
jet
trackImpact parameter > 0(secondary decay vertex)
IP
jet
trackImpact parameter < 0(resolution)
IP
Reconstruct secondary vertexAlso use semileptonic decays
-15 -10 -5 0 5 10 151
10
102
103
104
Significance = dca/σ
~Resolution
-15 -10 -5 0 5 10 15
1
10
102
10
Significance = dca/σ
µ+jet sampleenhanced b-jet content
dijet sample
Meenakshi Narain, ICHEP2002, 7/29/2002
RunIIRunII Data and First Physics ResultsData and First Physics Results
• Delivered luminosity about 50 pb-1
• Mostly used to commission detector– Now complete
• First results from about 10 pb-1 of physics quality data– New center of mass energy → measure cross sections
– Exploit our High pT Physics capabilities at the energy frontier
• See also talks in parallel sessions – include results from both RunI and RunII
Meenakshi Narain, ICHEP2002, 7/29/2002
DzeroDzero talks during the parallel sessionstalks during the parallel sessions
• Jet measurement with the KT method (Ursula Bassler) • Minireview on Low Scale Gravity and ED at HERA/LEP/Tevatron
(Gregorio Bernardi )• Photon and Jet Physics at DØ (Marek Zielinski)• Search for SUSY at the Tevatron (Vishnu Zutshi)• W boson mass and width measurements (Sarah Eno)• Top physics at the Tevatron (Ia Iasvilli)• The DØ tracking system for Run II (George Ginther) • The DØ detector for Run II (Levan Babukhadia)
• +… a few more talks by CDF speakers which include DzeroRunII results.
Meenakshi Narain, ICHEP2002, 7/29/2002
BB--Mesons Mesons
) [GeV]+,K-µ,+µM(5 5.1 5.2 5.3 5.4 5.5 5.6 5.7
0
2
4
6
8
10
0.021 GeV±Mean = 5.277 0.014 GeV±Sigma = 0.057
D0 Run 2 PreliminaryB+(-)! J/ψ K+(-)
20 30 40 50 60 70 80 90 1010-4
10-3
10-2
10-1
1
Run 2 Preliminary D
MC
R = 0.5 Cone Jets
| < 0.6jetη|
> 4 GeV/cµTp
| < 0.8µη|
) < 0.7µR(jet, δ
EJet [GeV]T
d[n
b/10
GeV
]d/
σE
T
DØ Run 2 Preliminaryµ+jet Production Cross SectionDataMC Pythia
Thanks to my collaborators…Thanks to my collaborators…
33 US, 40 non USInstitutions:
Collaborators:334 from US 312 from non US institutions
Meenakshi Narain, ICHEP2002, 7/29/2002
ConclusionConclusion• First physics results at 1.96 TeV
– W and Z production cross sections– First generation LQ limits, Limit on Large Extra Dimensions– Lay foundation towards measurement of:
• B lifetime, b-quark cross sections, jet cross sections• Many High pT analyses in progress awaiting more luminosity
• Enormous progress made over the last year – detector performance optimization– developing analysis tools
• Improvements in store:– optimization of event reconstructionand selection procedures – Triggers and DAQ performance,– calibration, and alignment of the detectors
• Looking forward to collecting large integrated luminosity !
Meenakshi Narain, ICHEP2002, 7/29/2002
OutlookOutlook
• We are curious to see where it leads…
H?Prof. Peter Higgs
Meenakshi Narain, ICHEP2002, 7/29/2002
Status detailsStatus detailsAll subdetectors operational & reading out
All electronics, fronts ends, trigger & DAQ hardware installedRemaining: tuning up of the trigger/DAQ system2.5 106 int./sec396 nsec 5-10kHz 1000Hz 50HzDesign:
Level 2Level 1 Level 3 tapeNow: ~200Hz
2.5 106 int./sec396 nsec 50Hz~100Hz
Changed to new modern L3/DAQ system this year (done)
Commissioning and tuning up this systemVERY COMPLEX and high bandwidth systemExpect full rate by middle of fall of 2002
Large effort
Data taking continuesNo loss of physics at current luminosities
Meenakshi Narain, ICHEP2002, 7/29/2002
Backup SlidesBackup Slides
• Insert backup slides after this page
Meenakshi Narain, ICHEP2002, 7/29/2002
The Most Massive Candidate eventThe Most Massive Candidate event
M(diEM) = 377 GeV; cosθ* = 0.77; MET = 12.6 GeV;
EM2EM1
ET = 106.2 GeVη = -2.10ϕ = 2.19No track match
ET = 120.3 GeVη = 0.10ϕ = 5.27No track match
Meenakshi Narain, ICHEP2002, 7/29/2002
LuminosityLuminosity
Total Run 2 luminosity delivered & used A snapshot: July 1 to July
6, 2002
Meenakshi Narain, ICHEP2002, 7/29/2002
BB--Mesons Mesons
) [GeV]+,K-µ,+µM(5 5.1 5.2 5.3 5.4 5.5 5.6 5.7
0
2
4
6
8
10
0.021 GeV±Mean = 5.277 0.014 GeV±Sigma = 0.057
D0 Run 2 PreliminaryB+(-)! J/ψ K+(-)
20 30 40 50 60 70 80 90 10010-4
10-3
10-2
10-1
1
Run 2 Preliminary Data
MC
R = 0.5 Cone Jets
| < 0.6jetη|
> 4 GeV/cµTp
| < 0.8µη|
) < 0.7µR(jet, δ
EJet [GeV]T
d[n
b/10
GeV
]d/
σE
T
DØ Run 2 Preliminaryb-quark Production Cross SectionDataMC Pythia