recent results from tevatron
DESCRIPTION
Recent results from TEVATRON. Yuji Takeuchi (Tsukuba) for CDF and DZero collaborations 16 th YKIS Conference Progress in Particles Physics 2008 Feb. 18 th , 2009. Contents Latest Results from ∫ Ldt~3fb -1 Top quark Search for SM Higgs. Tevatron Run II Still at the Energy Frontier. - PowerPoint PPT PresentationTRANSCRIPT
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Recent results from TEVATRON
Yuji Takeuchi (Tsukuba)for CDF and DZero collaborations
16th YKIS ConferenceProgress in Particles Physics 2008
Feb. 18th, 2009
Contents•Latest Results from ∫Ldt~3fb-1
•Top quark•Search for SM Higgs
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CDFD0
Chicago
TEVATRON
MAIN INJECTOR
Tevatron Run IIStill at the Energy Frontier
Tevatron:• The world's highest-energy particle collider• Proton-antiproton collisions at √s = 1.96 TeV• Tevatron is performing really well:
Reach 6 fb-1 and 7~8 fb-1 expected by the end of 2009.
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CDF/DZero
CDF:• 8 layer silicon vertex detector• 8 super layer drift chamber• 1.4T solenoid• Good particle identification (K,)• Central/Wall/Plug calorimeters• Scintillator+drift chamber muon
detectors
DZero:• 8 layer silicon vertex detector• 16 layers scintillating fibers• 2T solenoid• Central/Endcap calorimenters• 1.8T toroid• 3 layer muon scintillator + drift
tubes (Extended muon coverage)
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• Continually establishing new records! – Peak luminosity
~3.5×1032 cm-2 s-1
– Weekly integrated luminosity78 pb-1
– Annual integrated luminosity1.8 fb-1 (US FY 2008)
– Avarage pbar accumulation rate
• 21×1010 pbar/ hour
• Very stable operation– Maximizing integrated
luminosity– 10 weeks shutdown in 2009
summer
Tevatron Status
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Integrated Luminosity
• Integrated luminosities for each US FY– Extrapolation for FY2009:
≳ 2 fb-1
FY 2009
FY08
FY09
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Projected Integrated Luminosity in Run II (fb-1) vs time
0
1
2
3
4
5
6
7
8
9
10
time since FY04
Inte
grat
ed L
umin
osity
(fb
-1)
FY08 start
8.75 fb-1
7.29 fb-1
Highest Int. Lum
Lowest Int. Lum
FY10 start
FY09 start
~ 1.8 fb-1 delivered in FY08
FY2010Fermilab plans to run (if budget allows)
and CDF/DZero are ready– Another 2 fb-1 , total ~9 fb-1
FY2009Run continues
~2 fb-1, total ~7 fb-1
Shutdown : 10 weeks from June 1
Tevatron Prospects
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Top Quark Physics
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Top Pair production
Dominant process
10%~20%
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Top Pair Signature
Categorize ttbar events into 3 decay types according to W decay mode
Dilepton• 2 lepton• 2 bjet• MET
All Hadronic• 6jet(2bjet)
Lepton+Jet• 1lepton• 4jet(2bjet)• MET
-1-1QCD
11 MeV) (200 ~ << GeV 1.5
Top quark decays as a naked quark Information on spin polarization and
momentum is directly transfered to decay products
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Top Pair Production Cross-section
• Now better than theoretical uncertainties• Luminosity is dominant source of uncertainty
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(ttbar)/(Z)
• The total uncertainty is decreased by 10% by taking the ratio of the top pair to the Z cross sections
+
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Top Quark Mass
Goal before Run-II started : 3 GeV/c2 with 2 fb-1
Now better than 1%
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Two Breakthroughs in Top Mass Measurements
Matrix Element Method• Use information on
leptons and jets maximally
in-situ Wjj JES calib.• JES (jet energy scale) calibration
using di-jet invariant mass from W• Incorporate JES into likelihood
function– L(Mt)→L(Mt,JES)
– Turn JES systematics into statistics Reduced with statistics of top events
Observables
Matrix element with a given top mass gives p.d.f. of observables
Likelihood function of top mass for a given set of observables
M jj→ MW
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Top Mass Measurement
World Best. Better than 1%
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W Helicity
• Information on t-W-b Vertex– Really V-A?– Really W boson?
In the standard model
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W Helicity Measurements
• Results support V-A coupling on t-W-b vertex so far
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Search for anomalous top quark couplings at DZero
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Measurement of dσ/dMtt at CDF
Singular Value Decomposition (SVD) of the response matrix
κ/MPl > 0.16 at the 95% CL
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Single Top Production
S-channel t-channel
• Cross-section |Vtb|∝ 2
– No need to assume unitarity of CKM matrix nor three generations of quarks
• On the assumption of CKM unitarity: Vtb = 0.99• 3 generations: Can be derived from Br(t→Wb)
• Important to understand bkg of WH event for low mass higgs (mH<130 GeV) – Benchmark of higgs search in WH
WH : Single Top ~1:10
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Single Top Summary
• CDF is now preparing combined results for 3.2fb-1
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Single Top Measurement with ME Technique
Signal region
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Single Top Prospects
• Expected uncertainty on Vtb as a function of ∫Ldt• Uncertainties arise from
– Experiment– Cross-section dependence on Mt– Factorization and Renormalization scales– Parton distribution functions– s
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W Boson Mass Prospects
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W Boson Mass
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W Boson MassWorld average : MW = 80.398± 0.025 GeV/c2
CDF: ΔMW=0.048 GeV/c2 (L=200pb-1)
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W Boson MassUnderstanding the detector
Bremsstrahlung tail
Instantaneous luminosity dependence
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W Boson Mass Prospects
• Single experiment sensitivity better than the current world average expected
• Will significantly improve constraint on the Higgs boson mass
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Constraining the Higgs boson mass
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SM Higgs Search
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Low mass Higgs region:m
H<135 GeV/c2
H → bb dominant decay. Search for associated W/Z production.
High mass Higgs region:m
H>135 GeV/c2
H → WW dominant decay. Gluon fusion production search (gg → H).
Higgs Cross-section and BR
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WHlbbCDF: Updated on Nov 7, 2008• Combined result of NN and
ME+BDT• Improved by 15%• Limit/SM < 4.8 @115 GeV/c2
DZero: Updated on Feb 5, 2009• Limit/SM < 6.7 @115 GeV/c2
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Combined Limits
DZero: Updated on Aug 2, 2008• New WH lbb result NOT
included
WHlbbWHWWW
CDF: Updated on Jan 16, 2009• Updates since last summer
– WHlbb
– WH WWW
– ZH llbb
ZHllbb
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Higgs Exclusion @ Tevatron
• One mass, 170 GeV, excluded @ 95% CL• A 15 GeV window [162:177] excluded @ 90% CL
CDF+DZero combinationUpdated on Jul 30, 2008
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Projections
• CDF+DZero projections assuming they perform the same• Possible improvements:
– Acceptance, Analysis method, jet/MET resolutions, ...
• Good possiblity to see 3 evidence to a Higgs of 160 GeV/c2
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Conclusion
• Tevatron is operating well. Better than ever!• CDF and DZero experiment are ready to run FY2010.
∫Ldt ~ 9 fb-1 is expected.
• Top quark properties are being measured more and more precisely. Mass precision is now less than 1%. Top quark properties are consistent with SM so far.
• We are sensitive to a Higgs of 160 GeV/c2.
• Stay tune for interesting results with ≳ 3fb-1 in 2009!