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Latest Results from CDF: Flavour Physics and New Developments in Top Physics at Tevatron

This research study by Professor Koji Sato from the Graduate School of Mathematical and Physical Sciences at the University of Tsukuba discusses the latest results from the Collider Detector at Fermilab (CDF) in regards to flavour physics and new developments in top physics at Tevatron. The study provides insights into particle physics at the highest energy levels and focuses on the properties and measurements of top quarks.

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Latest Results from CDF: Flavour Physics and New Developments in Top Physics at Tevatron

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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. • Direct measurement of Top quark properties have only been reported by CDF/D0. • 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 _ X ttbar decay modes: _ 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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