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Measurement of the Top Quark mass using data from CDF experiment at Tevatron

Measurement of the Top Quark mass using data from CDF experiment at Tevatron. Fedor Prokoshin. Part 2. Tevatron :. Top Production at Tevatron. single top:. top-antitop pairs:. 85%. ~2 pb. 15%. ~1 pb. ~ one top event every 10 BILLION inelastic collisions. Hadronization time.

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Measurement of the Top Quark mass using data from CDF experiment at Tevatron

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  1. Measurement of the Top Quark mass using data from CDF experimentat Tevatron FedorProkoshin Part 2

  2. Tevatron: Top Production at Tevatron single top: top-antitop pairs: 85% ~2 pb 15% ~1 pb ~ one top event every 10 BILLION inelastic collisions

  3. Hadronization time NO top hadrons Top quark decay final state given by W+ W- decays

  4. Events where neither of the W bosons decay by the lepton channel can be referred to as 'all jets‘ or ‘hadronic’ since all the detector sees is hadron jets. Events in which both the positively charged W boson and the negatively charged W boson decay by the lepton channel can be known as the 'dilepton' channel. Events in which only one W boson decays by the lepton channel can be known as the single-lepton(or lepton+jets) channel. Event Classification qqqqbb hadronic 44% Lnlnbb dilepton11 (5)% lnqqbb lepton+jets44 (30)%

  5. Event selection • 1 energetic (ET>20 GeV) isolated lepton (e,μ) • 4 energetic (ET>15 GeV) jets (of which 2 b jets) • Large ETmis > 20 GeV

  6. Backgrounds • Diboson • Single top • W+multijet • W+LF jets • W+HF jets • Non-W (QCD) • EWK 10 % • W+jets 65 % • non-W 23 % TOTAL BACKGROUND 32 %

  7. B hadrons are long-lived semileptonic B hadron decay Vertex displaced tracks Soft Lepton Tagging Tagging B-jets • Top events contain B hadrons • Only 1-2% of dominant W+jets background contains heavy flavor • Great S/B improvement 55% 0.5% Top Event Tagging Efficiency False Tag Rate (QCD jets) 15% 3.6%

  8. Lepton+jets • Undetected neutrino • Px and Py from Et conservation • 2 solutions for Pz from MW=Mln • Leading 4 jets combinatorics • 12 possible jet-parton assignments • 6 with 1 b-tag • 2 with 2 b-tags • ISR + FSR final state: CDF sees:

  9. Jet Assignment

  10. Mass templates M top 140 200 Mi=140 Mi=160 Mi=180 Mi=200

  11. Signal parameterization

  12. Background Template

  13. FINAL FIT Mtop = 168.9 ± 2.2 (stat) ± 4.2 (syst) GeV/c2

  14. Summary of current results http://www-cdf.fnal.gov/physics/new/top/public_mass.html

  15. BACKUP SLIDES

  16. Dilepton

  17. KINEMATICS Equations Constraints Observables: Unknown

  18. Ch square fit

  19. Parametrisation

  20. Likehood

  21. Top pair decay modes

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