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. 2 nd, 2011 Contents CDF/Tevatron status CDF/Tevatron status Top physics Top physics –ttbar spin correlation ( 武政＠若手セッション ) B physics ( 三宅 ) B physics ( 三宅 ) Higgs search （永井） Higgs search （永井）

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

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

4 Peak luminosity 4.14×10 32 cm -2 s -1 Weekly integrated luminosity 84 pb -1 /week Annual integrated luminosity 2.5 fb -1 (US FY 2010) Tevatron Status FY02 FY03 FY04 FY05 FY06 FY07 FY08 FY09 FY10 FY11  12.6×10 32 cm -2 s -1 (ATLAS)  ~1fb -1 /month(ATLAS)

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

6 jets HF W Z WW ZZ WW tt WZ single top ZZ Higgs New Physics? 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 Categorize ttbar events into 3 decay types according to W decay mode Dilepton 2 lepton 2 b-jet MET All Hadronic 6 jet(2 b-jet) Lepton+Jet 1 lepton 4 jet(2 b-jet) MET

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

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  M t =1.09 GeV/c 2 (0.63%)  M t <1GeV/c 2 can be reachable

14 Top charge (Q t =2/3 vs 4/3) P-value for SM: P-value for XM: l+jet channel l-b paring  kinematics: Ppairing=83% Jet charge  kinematics: P JQ =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 top spin polarization vector in top rest flame down-type

16 Information on Wtb Vertex Really W boson? Really V-A? In SM t b Left t b Long

17 Consistent with t  Wb vertex

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

19 RunII 5.3fb -1 l+jets results(1)  y t (=y t -y tbar ) Background subtracted, then unfolded back to parton level. A ttbar =  0.074

20 RunII 5.3fb -1 l+jets results(2) Look at parton-level asymmetry as functions of  y t and M ttbar A ttbar (  y t >1.0) =   A ttbar (M ttbar >450GeV) =    To be compared to A pred (M ttbar >450GeV) =  0.013

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

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

23 F-B asymmetry at other experiments Background subtracted asym. A ttbar = 8  4(stat)  1(syst) % To be compared: A Pred = % In pp collision quark from valence, anti-quark from sea: quark tends to larger x A fb >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/c 2 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