Recent results from TEVATRON Yuji Takeuchi Tsukuba for
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~3 fb-1 • Top quark • Search for SM Higgs 1
Tevatron Run II Still at the Energy Frontier Chicago CDF D 0 TEVATRON MAIN INJECTOR Tevatron: • The world's highest-energy particle collider • Proton-antiproton collisions at √s = 1. 96 Te. V • Tevatron is performing really well: Reach 6 fb-1 and 7~8 fb-1 expected by the end of 2009. 2
CDF/DZero CDF: • • • 8 layer silicon vertex detector 8 super layer drift chamber 1. 4 T solenoid Good particle identification (K, p) Central/Wall/Plug calorimeters Scintillator+drift chamber muon detectors DZero: • • • 8 layer silicon vertex detector 16 layers scintillating fibers 2 T solenoid Central/Endcap calorimenters 1. 8 T toroid 3 layer muon scintillator + drift tubes (Extended muon coverage) 3
Tevatron Status • Continually establishing new records! – Peak luminosity ~3. 5× 1032 cm-2 s-1 – Weekly integrated luminosity 78 pb-1 – Annual integrated luminosity 1. 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 4
Integrated Luminosity • Integrated luminosities for each US FY – Extrapolation for FY 2009: FY 08 FY 09 ≳ 2 fb-1 FY 2009 5
Tevatron Prospects FY 2009 FY 2010 Run continues ~2 fb-1, total ~7 fb-1 Shutdown ： 10 weeks from June 1 Fermilab plans to run (if budget allows) and CDF/DZero are ready – Another 2 fb-1， total ~9 fb-1 FY 10 start FY 09 start 8. 75 fb-1 7. 29 fb-1 Highest Int. Lum ~ 1. 8 fb-1 delivered in FY 08 Lowest Int. Lum FY 08 start 6
Top Quark Physics 7
Top Pair production Dominant process 10%~20% 8
Top Pair Signature Dilepton Lepton+Jet All Hadronic • 2 lepton • 2 bjet • MET • 1 lepton • 4 jet(2 bjet) • MET • 6 jet(2 bjet) Top quark decays as a naked quark è Information on spin polarization and momentum is directly transfered to decay products Categorize ttbar events into 3 decay types according to W decay mode 9
Top Pair Production Cross-section • Now better than theoretical uncertainties • Luminosity is dominant source of uncertainty 10
(ttbar)/ (Z) + • The total uncertainty is decreased by 10% by taking the ratio of the top pair to the Z cross sections 11
Top Quark Mass Goal before Run-II started : 3 Ge. V/c 2 with 2 fb-1 Now better than 1% 12
Two Breakthroughs in Top Mass Measurements in-situ W jj JES calib. Matrix Element Method • Use information on leptons • JES (jet energy scale) calibration using di-jet invariant mass from W and jets maximally Observables • Incorporate JES into likelihood function – L(Mt)→L(Mt, JES) – Turn JES systematics into statistics Reduced with statistics of top events Matrix element with a given top mass gives p. d. f. of observables Likelihood function of top mass for a given set of observables Mｊｊ→MW 13
Top Mass Measurement World Best. Better than 1% 14
W Helicity • Information on t-W-b Vertex – Really V-A? – Really W boson? In the standard model 15
W Helicity Measurements • Results support V-A coupling on t-W-b vertex so far 16
Search for anomalous top quark couplings at DZero 17
Measurement of dσ/d. Mtt at CDF Singular Value Decomposition (SVD) of the response matrix κ/MPl > 0. 16 at the 95% CL 18
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 (m. H<130 Ge. V) – Benchmark of higgs search in WH WH ： Single Top～１：１０ 19
Single Top Summary • CDF is now preparing combined results for 3. 2 fb-1 20
Single Top Measurement with ME Technique Signal region 21
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 as 22
W Boson Mass Prospects 23
W Boson Mass 24
W Boson Mass World average : MW = 80. 398± 0. 025 Ge. V/c 2 CDF: ΔMW=0. 048 Ge. V/c 2 (L=200 pb-1) 25
W Boson Mass Understanding the detector Bremsstrahlung tail Instantaneous luminosity dependence 26
W Boson Mass Prospects • Single experiment sensitivity better than the current world average expected • Will significantly improve constraint on the Higgs boson mass 27
Constraining the Higgs boson mass 28
SM Higgs Search 29
Higgs Cross-section and BR Low mass Higgs region: m. H<135 Ge. V/c 2 H → bb dominant decay. Search for associated W/Z production. High mass Higgs region: m. H>135 Ge. V/c 2 H → WW dominant decay. Gluon fusion production search (gg → H). 30
WH l bb CDF: DZero: Updated on Nov 7, 2008 • Combined result of NN and ME+BDT • Improved by 15% • Limit/SM < 4. 8 @115 Ge. V/c 2 Updated on Feb 5, 2009 • Limit/SM < 6. 7 @115 Ge. V/c 2 31
Combined Limits ZH llbb WH lnbb WH WWW CDF: DZero: Updated on Jan 16, 2009 • Updates since last summer Updated on Aug 2, 2008 • New WH l bb result NOT included – WH l bb – WH WWW – ZH llbb 32
Higgs Exclusion @ Tevatron CDF+DZero combination Updated on Jul 30, 2008 • One mass, 170 Ge. V, excluded @ 95% CL • A 15 Ge. V window [162: 177] excluded @ 90% CL 33
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 Ge. V/c 2 34
Conclusion • Tevatron is operating well. Better than ever! • CDF and DZero experiment are ready to run FY 2010. ∫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 Ge. V/c 2. • Stay tune for interesting results with ≳ 3 fb-1 in 2009! 35
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