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ＣＤＦの最新結果

ＣＤＦの最新結果. 筑波大学数理物質研究科 佐藤構二 「フレーバー物理の新展開」研究会 2010 年　 2 月 23 日. Tevatron Run II. p – p collisions at s = 1.96 TeV (1.8 TeV in Run I). Run II started in Summer 2001. Particle physics at the highest energy!. CDF Collaboration. ~600 people from 14 Countries.

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ＣＤＦの最新結果

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  1. ＣＤＦの最新結果 筑波大学数理物質研究科 佐藤構二 「フレーバー物理の新展開」研究会2010年　2月23日

  2. Tevatron Run II • p – p collisions at s = 1.96 TeV (1.8 TeV in Run I). • Run II started in Summer 2001. • Particle physics at the highest energy!

  3. CDF Collaboration • ~600 people from 14 Countries. • Japanese collaboration • KEK • Osaka City University • Okayama University • University of Tsukuba • Waseda University

  4. Tevatron Run II — Luminosity Status • Typical Peak Luminosity : 3  1032 cm2 s-1. • Delivers 60 - 70 pb-1/week. • Integrated Luminosity • Delivered: 7.9 fb-1 ,Recorded: 6.7 fb-1. • Recent analyses typically use up to 5 fb-1. • Running in 2010. Possible running in 2011. Run II since Summer 2001

  5. Collider Detector at Fermilab Multi-purpose detector • Tracking in magnetic field. • Coverage |h|<~1. • Precision tracking with silicon. • 7 layers of silicon detectors. • EM and Hadron Calorimeters. • sE/E ~ 14%/E (EM). • sE/E ~ 84%/E (HAD). • Muon chambers.

  6. Contents • Top physics • Pair production cross section • Mass measurement • Property measurements • Single top observation • Direct search for Higgs Boson • Standard Model Higgs

  7. Top Physics

  8. b q’ p Top Physics at Tevatron • Top quark was observed at TEVATRON in 1995. • Top is still the least studied observed particle. • Any deviation from SM might suggest new physics!! • Top mass is unexpectedly heavy ~35mb. • Special role in EWSB? W helicity Top Mass l+ Top Width Anomalous Couplings Top lifetime Production cross-section W+ CP violation Top Charge Resonance production p n t b Production kinematics _ ttbar decay modes: X _ ttbar Spin correlation _ t q Rare/non SM Decays W- _ Branching Ratios |Vtb|

  9. Top Pair Cross Section (L+jets) • Top quark is mostly produced in pairs at Tevatron. • s(NLO) = 7.4 +0.5-0.7 pb ~15% ~85% • Event selection: • 1 lepton Pt>20, |h|<2.0 • MET>25 • ≥3 jets with Pt>20 , |h|<2.0 • ≥ 1 jet b-tagged stt = 7.04 ± 0.34 (stat.) ± 0.55 (syst.) ± 0.43 (lumi.) pb The dominant luminosity systematic can be canceled out by measuring ratio stt /sZ. stt = 7.14 ± 0.34 (stat.) ± 0.58 (syst.) ± 0.14 (theory) pb (4.3 fb-1)

  10. Top Pair Cross Section • Cross section is sensitive to both production and decay anomaly. • The difference between different decay modes might indicate new physics. • CDF measures xs with various decay modes/methods, and the results are consistent with SM.

  11. b l+ g q 100% t W+ n 15% 85% q t q g W- 100% q’ b L+jets Top Mass Measurement with Matrix Element Method • Construct likelihood for Mt and Jet Energy Scale (JES) with Signal Matrix Element calculation. • JES had been the dominant systematic source. • Simultaneously fit Mtop and JES. • JES constrained by hadronically decaying W→qq’ in candidate events. Constrain Dijet mass To MW mt = 172.6±0.9 (stat.)±0.7 (JES)±1.1 (syst.) GeV/c2 = 172.6 ± 1.6 (total) GeV/c2

  12. Top Mass Tevatron Combination (winter 2009) Use only best analyses from each decay mode, each experiment. Mtop = 173.1±1.3 GeV/c2 Before Run II results (Spring 2004): Mtop = 178.0  4.3 GeV/c2 mhiggs251 GeV/c2 (95% CL) • Mhiggs < 157 GeV/c2 (95% CL) . • Mhiggs < 186 GeV/c2 w/ LEP direct search limit.

  13. Search for tt Resonance Analysis in all hadronic channel. • Cross section limit on neutral vector resonance. • Top color assisted technicolor predicts leptophobic Z’ with strong coupling to 3rd generation quarks. b q q t W+ ? q’ q’’ q t W- q’’’ b No significant excess Limit on Z’ with G=1.2%xMZ’ MZ’ > 805 GeV (2.8 fb-1)

  14. b l+ g q t W+ n q t q g W- q’ b Forward Backward Assymmetry • L+jets analysis. • Measure rapidity yhad of hadronically decayed top. • SM predicts at NLO: Afbpred. = 0.05 0.015 y>0 y<0 Ql yhad Afb = 0.193 +- 0.065 (stat) +- 0.024 (syst) (3.2fb-1) ~2s effect!

  15. Spin Correlation • Top does NOT hadronize (unique about top quark). • SM prediction : ttop~0.4x10-24 s<< 1/LQCD10-23 s • Spin information will be inherited by decay products. SM predicts k~0.8. Signal: k = 1 k = -1 Bkgd: 2.8 fb-1 -0.455<κ<0.865 (68% C.L.)

  16. Single Top Production • Top quark is sometimes singly produced Tevatron. • 1 lepton, MET, 2 or 3 jets • S/B separation by Matrix Element (ME) • Event selection: • 1 lepton, Pt>20 • MET>25 • 2 or 3 jets, Pt>20, |h|<2.8 • ≥1 jet b-tagged s-channel bkgd ME Signal ME Vtb Vtb* • 0.884±0.11 pb(NLO) t-channel Vtb* Vtb 4.3 s effect st+s-chan = 2.5 +0.7-0.6 pb(3.2 fb-1) • 1.98±0.25 pb(NLO)

  17. Single Top Combined Result t-channel s-channel Vtb* Vtb Vtb Vtb* • 0.884±0.11 pb(NLO) • 1.98±0.25 pb(NLO) 5.0 s observation!! st+s-chan = 2.3 +0.6-0.5 pb st-chan = 0.8±0.4pb ss-chan = 1.8+0.7-0.5pb |Vtb| = 0.91 ± 0.11 (exp.) ± 0.07 (theory)

  18. Direct Search for SM Higgs Boson

  19. Production Cross Sections recently observed by CDF!

  20. SM Higgs Properties at Tevatron • mH<135 GeV (low mass): • gg→H→bb is difficult to see. • Look for WH/ZH with leptonic vector boson decays. • mH>135 GeV (high mass): • Easiest to look for H→WW with one or two W decaying to lepton. bb WW

  21. WHlbb (low mass) • S/B separation by NN. • Four tagging categories, using 3 algorithms (including NN tagger). • New NN b-jet energy correction See Nagai’s presentation!

  22. ZH  ll+bb (low mass) l • 3 b-tag categories with 2 algorithms. • S/B separation by NN. • Improved lepton coverage with forward EM clusters. • Dominant backgrounds: • Z+jets, top, diboson tight 2 b-tag l 1 b-tag (mH=120 GeV)

  23. WH/ZHMET+bb (low mass) • Target process: ZHnnbb • Also complementary to WHlnbb and ZHllbb searches. • 3 b-tag categories with 2 algorithms. • S/B separation by NN. • Dominant backgrounds: • QCD with MET miscalculation • W/Z+jets, top, diboson tight 2 b-tag + loose 2 b-tag (mH=115 GeV)

  24. H  WW*l+ l- (high mass) • Opposite sign 2 leptons. • Lepton acceptance improved by using isolated tracks. • S/B separation by NN. • Matrix element calculation result input to NN. • Newly including low Mllchannel. • Dominant background • DY, Diboson, top (mH=165 GeV)

  25. Summary of Higgs Search • Elaborate analyses are already there for most promising channels. • Striving for further improvement. • New channels are being explored.

  26. CDF Combination

  27. Tevatron Combination

  28. B Physics See Miyake’s presentation!

  29. Summary • TEVATRON and CDF Run II are operating pretty well! • CDF has already collected ~6.7 fb-1 of data. • Possible running in 2011. • CDF keeps producing impressive physics results. • Top properties are studied closely. • Top pair cross section precision is 6.5% (better than theory). • Single top production has been observed. • Top mass precision is 0.7 %. • Higgs boson is intensively searched for, with increasing sensitivity. • 163<MH<166 GeV mass region has been excluded. • No obvious signs of new physics so far, but stay tuned! • CDF is keeping a heavy challenge on SM.

  30. TEV status Backup

  31. Tevatron Status

  32. Tevatron FY2011 Projection 12.0 fb-1 FY11 start 10.0 fb-1 FY10 start Highest Int. Lum Lowest Int. Lum Real data for FY02-FY09

  33. Higgs Backup

  34. WH WWW*l± l± +jets(high mass) • Same sign 2 leptons. • Lepton acceptance improved by using isolated tracks. • S/B separation by NN. • Dominant background • DY, Diboson, W+jets

  35. CDF Higgs Sensitivity Projections

  36. tight 2 b-tag ZH  ll+bb (low mass) l • S/B separation by NN. • 3 b-tag categories with 2 algorithms. • Improved lepton coverage with forward EM clusters. • Dominant backgrounds: • Z+jets, top, diboson l loose 2 b-tag 1 b-tag (mH=120 GeV)

  37. WH/ZHMET+bb (low mass) • Target process: ZHnnbb • Also complementary to WHlnbb and ZHllbb searches. • S/B separation by NN. • 3 b-tag categories with 2 algorithms. • Dominant backgrounds: • QCD with MET miscalculation • W/Z+jets, top, diboson tight 2 b-tag loose 2 b-tag 1 b-tag (mH=115 GeV)

  38. H  WW*l+ l- (high mass) • Opposite sign 2 leptons. • Lepton acceptance improved by using isolated tracks. • S/B separation by NN. • Matrix element calculation result input to NN. • Newly including low Mllevents. • Dominant background • DY, Diboson, top (mH=165 GeV) Mll <16 GeV channel

  39. Tools Backup

  40. b q l+ , g q 100% t q’ W+ n , 15% 85% t q g W- 100% b Ttbar diagram q’’ l- , q’’’ n ,

  41. B-Tagging • B-jet tagging by secondary vertex displacement from the primary vertex. • B-tagging reduces wrong jet-parton assignment as well as background events.

  42. B-tag 2

  43. Jet Probability Algorithm (1)

  44. Jet Probability Algorithm (2)

  45. Top Mass Backup

  46. b l+ g q 100% t W+ n 15% 85% q t q g W- 100% q’ b L+jets Top Mass Measurement with Matrix Element Method • Construct likelihood for Mt and Jet Energy Scale (JES) with Signal Matrix Element calculation. • JES had been the dominant systematic source. • Simultaneously fit Mtop and JES. • JES constrained by hadronically decaying W→qq’ in candidate events. Constrain Dijet mass To MW mt = 172.6±0.9 (stat.)±0.7 (JES)±1.1 (syst.) GeV/c2 = 172.6 ± 1.6 (total) GeV/c2

  47. CDF Top Mass Measurements

  48. TEVATRON Top Mass Comb.

  49. Top Mass Tevatron Combination (winter 2009) Use only best analyses from each decay mode, each experiment. Mtop = 173.1±1.3 GeV/c2 • Mhiggs < 157 GeV/c2 (95% CL) . • Mhiggs < 186 GeV/c2 w/ LEP direct search limit.

  50. Top Mass Tevatron Combination (winter 2009) Use only best analyses from each decay mode, each experiment. Mtop = 173.1±1.3 GeV/c2 Before Run II results (Spring 2004): Mtop = 178.0  4.3 GeV/c2 mhiggs251 GeV/c2 (95% CL) • Mhiggs < 157 GeV/c2 (95% CL) . • Mhiggs < 186 GeV/c2 w/ LEP direct search limit.

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