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CDF の最新結果

CDF の最新結果. 武内勇司 ( 筑波大 ) for CDF collaboration 特定領域「フレーバー物理の新展開」研究 2011 鹿の湯ホテル Jul. 2 nd , 2011. Contents CDF/Tevatron status Top physics ttbar spin correlation ( 武政＠若手セッション ) B physics ( 三宅 ) Higgs search （永井）. Tevatron Run II. Chicago. CDF. D0. TEVATRON. MAIN INJECTOR.

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CDF の最新結果

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  1. CDFの最新結果 武内勇司 (筑波大) for CDF collaboration 特定領域「フレーバー物理の新展開」研究2011 鹿の湯ホテル Jul. 2nd, 2011 • Contents • CDF/Tevatron status • Top physics • ttbar spin correlation (武政＠若手セッション) • B physics (三宅) • Higgs search （永井）

  2. Tevatron Run II Chicago CDF D0 TEVATRON MAIN INJECTOR Tevatron • Proton-antiproton collisions at √s = 1.96 TeV • Shutdown on Sep. 30, 2011 • Final dataset: ~10 fb-1 expected for physics

  3. Silicon vertex detector (1+5+2 layers) Central drift chamber (8 super layers) 1.4T solenoid Good particle identification (K,p) Central/Wall/Plug calorimeters Scintillator+drift chamber muon detectors The CDF IIDetector

  4. Tevatron Status • Peak luminosity 4.14×1032 cm-2 s-1 • Weekly integrated luminosity 84 pb-1/week • Annual integrated luminosity 2.5 fb-1 (US FY 2010) 12.6×1032 cm-2 s-1(ATLAS) ~1fb-1/month(ATLAS) FY11 FY10 FY09 FY08 FY07 FY06 FY05 FY04 FY03 FY02

  5. Integrated Luminosity • Delivered 11.3fb-1, Recorded 9.3fb-1 ATLAS x tt ratio ATLAS

  6. jets HF New Physics? W Z single top Higgs Wg Zg WW tt WZ ZZ Physics Programs at Tevatron • SM process • WZ,ZZ, Single-Top, ... • Top quark physics • Precise measurement • W mass, ... • Heavy flavor phyics • (bb)100s • Higgs search • Search for new physics 7TeV pp

  7. Top quark physics at CDF

  8. Heaviest elementary particle • play a special role in EWSB? • provides new test ground on Standard Model • Direct access to bare quark Top quark decays before hadronization Decays as a naked quark • Information on spin polarization and momentum at its production is directly transferred to decay products

  9. Dominant process at Tevatron 10%~20%

  10. Dilepton • 2 lepton • 2 b-jet • MET • Lepton+Jet • 1 lepton • 4 jet(2 b-jet) • MET • All Hadronic • 6 jet(2 b-jet) Categorize ttbar events into 3 decay types according to W decay mode

  11. 343 cand./5.1fb-1 • ~105 bkg. • S/N~2.3 • 727 cand./4.3fb-1(4j, w/btag) • ~126 bkg. • S/N~4.8 • 105 cand./35pb-1 • ~21.6 bkg. • S/N~3.7 • 402 cand./35pb-1 • ~93 bkg. • S/N~3.3 ATLAS

  12. Consistent with prediction • Better uncertainty than theoretical uncertainties! • All channel, w/, w/o b-tag are consistent • Consistent with Br(t→Wb)~100%

  13. Top mass • Mt=1.09 GeV/c2 (0.63%) • Mt<1GeV/c2 can be reachable

  14. Top charge (Qt=2/3 vs 4/3) • P-value for SM: 0.134 • P-value for XM: 0.00014 • l+jet channel • l-b paring kinematics: Ppairing=83% • Jet charge kinematics: PJQ=61%

  15. top quark decays before losing polarization • V-A coupling • flight direction of down-type fermion from W carries 100% spin information of parent top quark • can “see” top quark spin at its production down-type top spin polarization vector in top rest flame

  16. 0.8 sum (SM) 0.6 t b longitudinal 0.4 t b left-handed right-handed 0.2 Long 0 Left -1 -0.5 0 0.5 1 • Information on Wtb Vertex • Really W boson? • Really V-A? In SM

  17. Consistent with tWb vertex

  18. 2 + 2 + V Backward Forward NLO prediction: Interference between LO and NLO Also presence of new physics could make asymmetry

  19. RunII 5.3fb-1 l+jets results(1) • yt(=yt-ytbar) • Background subtracted, then unfolded back to parton level. • Attbar = 0.1580.074

  20. RunII 5.3fb-1 l+jets results(2) • Look at parton-level asymmetry as functions of yt and Mttbar • Attbar(yt >1.0) = 0.611  0.210  0.147 • Attbar(Mttbar >450GeV) = 0.475  0.101  0.049 • To be compared to Apred(Mttbar >450GeV) = 0.088  0.013

  21. RunII 5.1fb-1 dilepton results(1) • Inherit Afb of parent ttbar • 0jet and 1jet events can be used as control sample to validate bkg shapes 0jet 1jet

  22. RunII 5.1fb-1 dilepton results(2) • Subtracting background • Apply corrections for acceptance and dilution due to reconstruction • Attbar = 0.42  0.15(stat)  0.05(stat)

  23. F-B asymmetry at other experiments • Background subtracted asym. • Attbar = 8 4(stat)  1(syst) % • To be compared: APred=1+2-1 % • In pp collision • quark from valence, anti-quark from sea: quark tends to larger x • Afb>0 |t|-|tbar| has positive asym. • AC=0.060  0.134(stat)  0.026(syst) • They claim same sensitivity as Tevatron with 1/fb!

  24. ここまでのSummary • Tevatron は今年の9月までの運転 • CDFのfull dataset は，約10/fbになる見込み • Top quark properties are consistent with SM so far • Except for forward-backward asymmetry at top pair production • Top quark properties are being measured more and more precisely, not to overlook any hint of new physics. • Uncertainty in top mass measurement: < 1 GeV/c2 • Uncertainty in pair production cross-section measurement is now better than theoretical uncertainties • Top quark 対生成の機構は,Tevatron とLHCで異なる • Cross-section やforward-backward asymmetry, Mtt 共鳴, ttbar spin correlation などは，対生成の機構に依存  Tevatron の解析もまだまだ重要 • 引き続きCDFのBの物理（三宅），Higgs探索(永井)のトークをお楽しみください

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