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High p T Φ in jets

High p T Φ in jets. Select pairs of oppositely charged tracks provided: p T (Jet)>50Gev; ( energetic jets ); ∆R(Φ,Jet)<0.4 ( tracks are assigned to the jet ); x ≣p T (K ± )/p T (jet)>0.1 ( energetic tracks ); N silicon >5 ( good tracks ); Χ/dof<2; ( good fit );

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High p T Φ in jets

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  1. High pT Φ in jets Select pairs of oppositely charged tracks provided: pT(Jet)>50Gev; (energetic jets); ∆R(Φ,Jet)<0.4 (tracks are assigned to the jet); x ≣pT(K±)/pT(jet)>0.1 (energetic tracks); Nsilicon>5 (good tracks); Χ/dof<2; (good fit); d0<1mm (coming from the interaction point); ∆Z0<5mm (same PI); ∑Q=0 (balanced charge); Rp≣pT(track1)/pT(track2)<1.7 (balanced momentum). 0.17 good pairs/jet are selected

  2. High pT Φ in jets Dmitry Milstein, Ohad Mamroud and E.D. Results based on a first look at 30pb-1 of the data.

  3. Naive K+K- mass distribution K+K- K+K+ / K-K- Nice signal: How can we estimate the combinatorical background?

  4. Naive K+K- mass distribution 1) Threshold disagreement 2) ‘High’ mass disagreement

  5. Removing π+π- which are consistent with originating in ρ0 decay • ‘High’ mass problem solved!

  6. Comparison with simulation Threshold problem is not simulated!

  7. Crude background subtruction Data MC m(K+K-) m(K+K-) Very nice narrow mass peak at mΦ.

  8. η distribution of Φ candidates η(Φ) Reasonable agreement

  9. comparing xΦ in MC and Data XΦ No agreement!

  10. Transverse momentum spectrum pT(Φ) pT of Φ is well simulated

  11. High pT Φ pT(Φ)>50GeV pT(Φ)>60GeV pT(Φ)>70GeV pT(Φ)>80GeV pT(Φ)>90GeV

  12. See a signal even when pT(Φ)>100 GeV!

  13. N(K+K−) = a1+a2∗mK+K− +a3/(mK+K− −a4)+a5∗exp(−((mK+K− −a6)2/a7)) fit subtraction

  14. Di-Jet Event Selection • The two leading jets contain most of the transverse energy in the event: • The two leading jets are in a back-to-back configuration:Df ( jet1, jet2) > 3.0.

  15. Good Event / Bad Event Selection • The di-jet asymmetry is defined by: • good jets are defined as all jets in the event in which YT < 0.1. • Bad jets, on the other hand, are found in events in which YT > 0.3. • 59% of the back-to-back di-jet events are classified as good and only 0.9% as bad.

  16. Position Dependence • We clearly see hot spots in which badly measured jets tend to hit. • Still need to look more carefully at the Dead OTX correction.

  17. Charged Particle Association w/ Jets • The charged fraction carried by a jet defined by: • A large amount of badly measured jets have a high value of Rcharge. • We suggest cutting on Rcharge < 1.1 to remove bad jets. • After this cut, the YT distribution looks much nicer 

  18. Charged Particle Association w/ Jets (2) • Cutting on Rcharge < 1.1 removes 15% of the badly measured jets and barely removes any well measured jets.

  19. backup

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