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The Latest Results of the CDF Experiment

The Latest Results of the CDF Experiment. Kazuhiro Yamamoto (Osaka City University) For the CDF Collaboration March 26, 2007 JPS Meeting at Tokyo Metropolitan University. CDF Experiment. Being performed at Tevatron accelerator in Fermilab. Proton-antiproton collision at s = 1.96 TeV.

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The Latest Results of the CDF Experiment

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  1. The Latest Results of the CDF Experiment Kazuhiro Yamamoto (Osaka City University) For the CDF Collaboration March 26, 2007 JPS Meeting at Tokyo Metropolitan University

  2. CDF Experiment • Being performed at Tevatron accelerator in Fermilab. • Proton-antiproton collision at s = 1.96 TeV. • Run II operation started in March 2001.

  3. Tevatron Accelerator CDF DØ SciBooNE Tevatron Main Injector

  4. CDF II Detector

  5. Accelerator performance Growing year by year Typical parameters Peak luminosity 2.0～2.5 x 1032 cm-2s-1 Weekly integrated lum. 40 pb-1/wk Run II record 2.923 x 1032 cm-2s-1 Tevatron Status

  6. Tevatron Status (2) • Integrated Luminosity

  7. CDF Collaboration ~700 physicists from 12 nations and 61 institutions Canada Spain USA IFAE, Barcelona CIEMAT, Madrid Univ. of Cantabria Argonne National Lab. Baylor Univ. Brandeis Univ. UC Davis UC Los Angeles UC San Diego UC Santa Barbara Carnegie Mellon Univ. Univ. of Chicago Duke Univ. Fermilab Univ. of Florida Harvard Univ. Univ. of Illinois The Johns Hopkins Univ. LBNL MIT Michigan State Univ. Univ. of Michigan Univ. of New Mexico Northwestern Univ. The Ohio State Univ. Univ. of Pennsylvania Univ. of Pittsburgh Purdue Univ. Univ. of Rochester Rockefeller Univ. Rutgers Univ. Texas A&M Univ. Tufts Univ. Wayne State Univ. Univ. of Wisconsin Yale Univ. McGill Univ. Univ. of Toronto Russia France JINR, Dubna ITEP, Moscow LPNHE, Paris Germany Korea Univ. Karlsruhe KHCL Switzerland Japan Univ. of Geneva KEK Okayama Univ. Osaka City Univ. Univ. of Tsukuba Waseda Univ. UK Glasgow Univ. Univ. of Liverpool Univ. of Oxford Univ. College London Taiwan Academia Sinica Italy Univ. of Bologna, INFN Frascati, INFN Univ. di Padova, INFN Pisa, INFN Univ. di Roma, INFN INFN-Trieste Univ. di Udine

  8. Top quark pair production • Top quarks are mainly produced in pairs via strong interaction. • Top quark decay • t ~ 10-24 sec, tWb (~100%) • W decays determine experimental signature 85% 15%

  9. Cross section measurement Dilepton : clean but small stat. Lepton + jets : fairly good S/N and stat. All jets : large stat. but poor S/N s(tt) = 9.0  1.3(stat)  0.5(syst)  0.5(lum) pb (L = 1070 pb-1) Top quark pair production (2) • New approach in dilepton channel Lepton (e/m) + isolated-track - increase acceptance - include t decays (to hadrons) No discrepancy to the SM was found yet.

  10. Template method Evaluate a variable strongly correlated with mt Compare data to MC with different mt inputs Matrix Element method Event likelihood by signal and background probability density Maximum likelihood to fit mt, JES(jet energy scale, and Cs(signal fraction) Top mass measurement PDF Transfer function

  11. Lepton + Jets channel All hadronic channel Top mass measurement (2) Lepton ET (PT) > 20GeV Jet ET > 15GeV Missing ET > 20GeV 1 b-tags QCD di-jet veto (0.5 < Df < 2.5) At lesat 6 jets with ET > 15GeV |h|<2 Good jet shape (Centrality, Aplanarity) 1 b-tags ET > 280GeV mt = 170.9  2.2(stat+JES)  1.4(syst) GeV/c2 = 170.9  2.6 GeV/c2 mt = 171.1  3.7(stat+JES)  2.1(syst) GeV/c2 = 171.1  4.3 GeV/c2

  12. Future prospect Uncertainty of <1% in the next years. We reached a precision of 1.1% in mt. Top mass measurement (3)

  13. Single top production • Top quark production via electroweak process. s-channel sNLO = 0.88  0.11 pb t-channel sNLO = 1.98  0.25 pb Phys. Rev. D70, 114012 (2004) • One of the best tests for the standard model Sensitivity to beyond the SM processes (FCNC, W’, 4th family, …) • Direct measurement of |Vtb| Unitarity test of CKM matrix • Important background of Higgs search Same final state as that of WHWbb

  14. Likelihood function analysis t-channel s-channel Single top production (2) Single top hidden behind background uncertainty  Makes counting experiment difficult i :indexes input variable • Neural network analysis • Matrix element analysis Still need a little more statistics

  15. Single top production (3) • DØ declared “evidence”. • Analyses using Boosted decision trees, Matrix elements, and Bayesian neural networks Combined result : ss+t = 4.9  1.4 pb (3.4s significance) hep-ex/0612052

  16. According to the SM, only WWg and WWZ vertices are allowed. Electroweak diboson production • EW diboson production gives information on trilinear gauge couplings. • Precise measurement of each coupling is one of the sensitive tests to the SM.  Window of new physics • Multi-lepton final states are major background sources of Higgs, SUSY, and other exotics.

  17. WW production • Two high-pT leptons and ET                                                        , s(WW) = 13.6  2.3(stat.)  1.6(syst.)  1.2(lum.) pb hep-ex/0605066 NLO calculation : s(WW) = 12.4  0.8 pb

  18. Wgmng channel Zgeeg channel Wg, Zg production s(Zg)•Br(Zee) = 4.9  0.3(stat.)  0.3(syst.)  0.3(lum.) pb s(Wg)•Br(Wmn) = 19.1  1.0(stat.)  2.4(syst.)  1.1(lum.) pb NLO : s(Zg)•Br(Z) = 4.7  0.4 pb NLO : s(Wg)•Br(Wn) = 19.3  1.4 pb A. Nagano (U. of Tsukuba) et al.

  19. Decays Wn and Z provide trilepton signature. Observation of WZ production CDF Observed 5.9s signal +1.8 s(WZ) = 5.0 (stat. + syst.) pb -1.6 NLO calculation : s(WZ) = 3.7  0.3 pb First observation of WZ production

  20. Search for ZZ production • Four charge-balanced leptons from Z0Z0 +-+- s(ZZ) < 3.8 pb (95% C.L.) SM NLO calculation : s(ZZ) = 1.40.1 pb Z0Z0e-/m-m+m-m+ candidate

  21. W mass measurement • mW : fundamental constant as well as mt in SM and BSM • Radiative corrections strongly correlated to Higgs mass Summer ’06

  22. W mass measurement (2) • Determine mW by comparing transverse mass (mT) b/w data and MC. • Charged-lepton track calibration • Cosmic, J/ymm, mm, Zmm • Calorimeter ET calibration • E/p, Zee • Charged-lepton track calibration • Cosmic, J/ymm, mm, Zmm • Calorimeter ET calibration • E/p, Zee • Hadronic recoil correction • pT balance in Z • QED effects • pT distribution tuning • Parton distribution • Hadronic recoil correction • pT balance in Z • QED effects • pT distribution tuning • Parton distribution

  23. W mass measurement (3) • Transverse mass spectra Wenchannel Wmnchannel

  24. W mass measurement (4) • Charged lepton ET (PT) • Missing ET (Neutrino PT)

  25. W mass measurement (5) • Transverse mass fit uncertainties (MeV)

  26. W mass measurement (6) • Fits to mT, pT, ET, and combine them all. mW(total comb.) = 80413  48 MeV/c2

  27. +33 SM Higgs mass : 76 GeV/c2 -24 EW global fit : Blue band SM / MSSM comparison hep-ph/0604147 and references are therein. mH < 144 GeV/c2 @ 95% C.L. W mass measurement (7) • New CDF result is the world’s most precise single measurement. World average uncertainty reduced ~15%

  28. Observation of Bs0 Oscillation 5s measurement of Bs0-Bs0 oscillation ! Dms = 17.77  0.10(stat.)  0.07(syst.) ps-1 Please see PRL97 242003 and slides of JPS-DPF2006 for the detail. http://www.phys.hawaii.edu/indico/contributionDisplay.py?contribId=743&sessionId=218&confId=3

  29. So far, Lb(udb) was the only established b-baryon. Next accessible baryon : Sb Observation of Sb and Sb* Sb+(uub, J=1/2), Sb-(ddb, J=1/2) Sb*+(uub, J=3/2), Sb*-(ddb, J=3/2) J=3/2 J=1/2

  30. Reconstruction of the decay chain: Sb(*)Lb0 + p Lc+ + p- p + K- + p+ Observation of Sb and Sb*(2) Lb0 reconstruction • Signals consistent with lowest lying Sb states at > 5s significant level. +2.0 m(Sb+) = 5808 (stat.)  1.7(syst.) MeV/c2 -2.3 +1.0 m(Sb-) = 5816 (stat.)  1.7(syst.) MeV/c2 -1.0 +1.6 m(Sb*+) = 5829 (stat.)  1.7(syst.) MeV/c2 -1.8 +2.1 m(Sb*-) = 5837 (stat.)  1.7(syst.) MeV/c2 -1.9

  31. Low mass Higgs (< 130 GeV/c2) • bb dominant  reconstruction of 2b jets • gghbb swamps on QCD background • Vh production is promising qq’Whnbb, qq’bb qqZh+-bb, nn bb, qqbb • High mass Higgs (130 ~ 200 GeV/c2) • WW dominant  multi-lepton signature gghWW+-nn qq’WhWWW*nnX qq  Zh  ZWW*nX Search for Higgs boson • SM Higgs boson at the Tevatron

  32. Recent progress : Zh bb High-pT opposite-sign dilepton 76GeV < M < 116GeV Njets 2 At least 1 b-tag Fit 2D-ANN outputs to extract possible signal fraction. Single b-tag Single b-tag Double b-tag Double b-tag Search for Higgs boson (2)

  33. Recent progress : gghWW nn High-pT opposite-sign dilepton Isolated tracks Large Missing ET Njet 1 Used Matrix Element calculation to extract possible Higgs signals. Search for Higgs boson (3) slim/sSM ~ 3 at Mh ~160GeV/c2

  34. Combined Result (1 fb-1) Recent progresses presented in the previous slides are not included in this plot. Contribution of Japanese institutes WH  lnbb (Univ. of Tsukuba, Waseda Univ.) WH  WWW (Osaka City Univ.) Updates coming soon … Search for Higgs boson (4) CDF Combination Tevatron Combination Summer ’06

  35. Summary • The Tevatron collider and detectors (CDF and DØ) are running in pretty good shape ! • 2.2 fb-1 has been recorded and ~1.1fb-1 was analyzed. • Some of the latest results were presented. • Tevatron Run II is scheduled to continue till the end of FY2009, and 6~8fb-1 of integrated luminosity is expected to be obtained. • Can we see any signs of Higgs/SUSY before LHC ?

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