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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 PhysicsofGenerations 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 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*)
Run II Projected: Dijet Mass Spectrum Dramatic increase in high pT cross sections Large gains in statistics
PRL 82 4769 (1999) Run II: Drell-Yan Constructive Interference Projected Limits (Bayesian) Destructive Interference
Kapow! 2VTX Tagging High P b Jets Isn’t that two there? Don Lincoln f
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
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
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.
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
Found = correct + fake Ptmin(track) = 500 MeV Efficiency = found/real Light quark jets has better tracking efficiency in core. DR (real and found)
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.