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d
u
“+”-Strom
Iwk+
u
d
“-”-Strom
Iwk-
d(u)
u(d)
“3”-Strom
Iwk3
W- W+ W3
n
p
“+”-Strom
+
p
n
“-”-Strom
-
n(p)
p(n)
“3”-Strom
3
- + 0
Parallele starker-schwacher Isospin:
3,3 ,,,,
',
',:,:
wkwkwk
weakstark
III
s
c
d
u
lI
d
u
n
pI
Folgerung GIM:Wenn schwache WW sich als SU(2)beschreiben laesst, dann muss es auch neutrale Stroeme geben!
CDF and DØ in Run II
New Silicon DetectorNew Central Drift ChamberNew End Plug CalorimetryExtended muon coverageNew electronics
Silicon Detector2 T solenoid and central fiber trackerSubstantially upgraded muon systemNew electronics
Driven by physics goals detectors are becoming “similar”: silicon, central magnetic field, hermetic calorimetry and muon systems
DØØ CDF
Top Quark Production and Decays
Top quarks at Tevatron are (mainly) produced in pairs via strong interaction
Top pair cross section at 1.96 TeV is 6.7 pb
In SM top decays 100% to WbClassification of top decays
is based on Ws decays
% e qq
e 1.2 2.5 2.5 14.8
1.2 2.5 14.8
1.2 14.8
qq 44.4
classification: di-lepton, lepton+jets, all jetsTwo b quarks in final state!!!
85%
15%
Detection of High Pt Objects
Electrons
Missing Et
Muons
Top and Higgs final decay products
electrons muons jets (b)
missing Et ()Detection and MC
optimization using well known objects
Selection of Top Quark Events
In triggering and analysis select events with high Pt leptons high Et multiple jets large missing Et () displaced vertex for b jets
“Di-lepton” mode has low backgrounds: di-bosons, Drell-Yan, ... but low statistics: ~5% for e, decays“Lepton+jets” very productive mode 6 times more decays then di-lepton mode main background W+jets good purity after b tagging“All jets” mode ~50% branching high QCD backgrounds, jets combinatoric
Run II Top Mass at CDFdi-leptons
l+jets, b tagged
l+jets GeV )(9.6)(5.176 2.170.16 syststatmt
GeV )(5.6)(9.174 1.77.7 syststatmt
GeV )(8.6)(6.179 4.63.6 syststatmt
… erst gut durch Kombinationvieler einzelner Analysen
Run II Top Quark Cross Section
Measurements demonstrate success of multiple top detection techniquesResults within errors consistent with NNLO SM predictions for 1.96TeV of 6.7pb
Tevatron Top Quark Mass
mt = 178.04.3 GeV
Run II top quark mass results from both detectors are available
TeV EWWG is working on combining Run II top mass measurement from CDF and DØØ
Systematic error (mainly jet energy scale)
is becoming limiting accuracy factor
Resonances in tt system?
MX > 560 GeV
No resonance production in tt system is expected in SM
Some models predict tt bound states, example: topcolor-assisted technicolor predicts leptophobic Z’ with strong 3rd generation coupling
Experimental check: search for bumps in tt effective mass spectrum
DØ, 125 pbØ, 125 pb-1-1
Background
Top
Total
