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The Physics of Generations Don Lincoln f

The Physics of Generations Don Lincoln f. Four Fermion General ‘Theory’. Theory consists of all terms of any chiral combinations. Drell-Yan Only. Tevatron Run I Limits. Drell-Yan. Units: TeV. QCD. Topics Currently Covered. All p p  two particles

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The Physics of Generations Don Lincoln f

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  1. The PhysicsofGenerations Don Lincoln f

  2. Four Fermion General ‘Theory’ Theory consists of all terms of any chiral combinations Drell-Yan Only

  3. Tevatron Run I Limits Drell-Yan Units: TeV QCD

  4. Topics Currently Covered • All pp  two particles • pp  m+m-(p resolution limited) • pp  e+e- (visa problems) • pp  en (MET questions) • pp  bb(two tagging approaches) • pp  jet-jet (most robust) • ds/dM & ds/d(cos q*)

  5. Run II Projected: Dijet Mass Spectrum Dramatic increase in high pT cross sections Large gains in statistics

  6. PRL 82 4769 (1999) Run II: Drell-Yan Constructive Interference Projected Limits (Bayesian) Destructive Interference

  7. Kapow! 2VTX Tagging High P b Jets Isn’t that two there? Don Lincoln f

  8. Motivation CDF: PRL 82 (1999) 2038 • High mass bb pairs can be sign of new physics (compositeness ?) • Problem • ~100:1 QCD:bb • Solutions • m tagging • 2nd VTX tagging • Impact parameter Fit to CDF qQCD calculation

  9. Decay Length Impact Parameter Current Work DR Question: Is failure to reconstruct secondary vertex due to tracking efficiency or vertex algorithm? DCA • Many variables have been tried for 2 VTX tag • Decay length & significance (2D & 3D) • Vertex Mass • DR • etc. • Only decay length and related quantities works. • Consider other tags eventually. Key Calorimeter Jet b hadron Secondary vertex Primary vertex Particles of Interest

  10. Efficiency only that of finding a ‘good’ secondary vertex What if ? We know that one can find secondary vertices by accident in light quark initiated events Eff(found) = Eff(luck) + Eff(right) Estimate Eff(right) ~ Eff(found) - Eff(light) No light statistics at high pt Reality could be worse Eyeball trends and guess.

  11. Decay Length (found and 2VTX) Found = found track 2VTX = used in secondary vertex Ptmin(track) = 500 MeV Efficiency = 2VTX/found Efficiency ~ Pt and flavor-initiator independent

  12. Found = correct + fake Ptmin(track) = 500 MeV Efficiency = found/real Light quark jets has better tracking efficiency in core. DR (real and found)

  13. Tracking ‘Efficiency’ vs Pt.

  14. Summary • Several different high mass di-object searches underway • In bb • Need to understand tracking efficiency in core of jets • Need to look more at muon tagging (but low mass reach) • Need to better understand b quark content from parton showers. • Active effort • Need more people thinking about it.

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