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B 0 ->D 0 (K - π + )K *0 (K + π - ) DC06 selections

B 0 ->D 0 (K - π + )K *0 (K + π - ) DC06 selections. Aurélien Martens (LAL – Orsay) Marie-Hélène Schune. Preselection. PT > 300 MeV P > 1 GeV MIPCHI2DV(PRIMARY) > 4. A bit tighter wrt the LHCb-2008-038 note (Stefania & Jacopo). K. ADAMASS < 50 MeV APT > 1 GeV VFASPF(VCHI2/VDOF) < 25

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B 0 ->D 0 (K - π + )K *0 (K + π - ) DC06 selections

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  1. B0->D0(K-π+)K*0(K+π-) DC06 selections Aurélien Martens (LAL – Orsay) Marie-Hélène Schune Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  2. Preselection PT > 300 MeV P > 1 GeV MIPCHI2DV(PRIMARY) > 4 • A bit tighter wrt the LHCb-2008-038 note (Stefania & Jacopo)... K ADAMASS< 50 MeV APT > 1 GeV VFASPF(VCHI2/VDOF) < 25 MIPCHI2DV(PRIMARY) > 4 π PT > 350 MeV(300 in the note) P > 2 GeV MIPCHI2DV(PRIMARY) > 4 π D0 K B0 ADAMASS< 150 MeV APT > 1 GeV VFASPF(VCHI2/VDOF) < 15 MIPCHI2DV(PRIMARY) > 4 ADAMASS< 500 MeV VFASPF(VCHI2/VDOF) < 5 BPVIPCHI2() < 25 FPVDIRA > 0.9995 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  3. Preselection results • DV v21r0 • DC06 Signal events : 214173 • DC06 stripped bbbar events : 982503 (corresponds to ~27Mevts) Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  4. Prescription on the DLLs • We systematically remove particles if the ΔKπln(Lhood) is not calculated (DLL == -999). • The gamma extraction using ADS is based on the asymmetry in the rates of Opposite and Same sign events. • The determination of the charge and the ID of the kaons and pions has to be robust. • Kills ~ 2% of the candidates Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  5. ΔKπln(Lhood) cuts on the kaons Bg : tracks from bb which are not true kaons K from K*0 K from D0 πfrom K*0 πfrom D0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  6. Σln(PT) & Σln(IPs) combined cuts on final state particles after previous cuts Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  7. cosθ* after previous cuts Asymmetry due to the cuts in the kinematic of K* daughters almost all of the Kaons are kept Slow pions are lost Cut the central part where no signal is expected p*π θ* Flight direction of K*0 p*K Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  8. cosθcuts on the D0 and the B0 after the previous cuts Bd Remove (at least) the negative part of the flight direction angle D0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  9. After all previous cuts D K* Bd Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  10. What are these 2 events ? They fall in the Opposite Sign category These two events are Bs0->D0 K*0 ! Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  11. What is their contribution ? (1/2) Dominant contribution to the Opposite sign (important) contribution to the Same sign (negligible) Neglecting the interference term : Opposite Sign Same Sign Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  12. What is their contribution ? (2/2) Opposite Sign (NBs = 30*NBd) The remaining contribution of the Bs0 peak under the B0 peak (3σ) is expected to be of the order of 20% in Opposite Sign. Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  13. Summary In loose mass window (+-500MeV) In tight mass window (+-50MeV) The 2 remaining bg events are specific : BS0bar->D0K*0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  14. Yields • Parameters : • Lint = 2*1015 b-1 • σbb = 500*10-6 b • fB = 0.4 • BR(B0->bar(D0)K*0) = 4.2*10-5 • BR(K*0->Kπ) = 2/3 • BR(D0->Kπ) = 3.89*10-2 • Asig = 0.1784 • Abg = 0.437 • εstripping= 982503/26977645 • WBdmass = 50/500 • Signal : • S = L*σbb*2*fB*BR*Asig *sig/Nsig • Background : • B = L*σbb*WBmass*Abg*εstripping*bg/Nbg Sig = 7072 (No L0) or 3007 (L0) Nsig = 214173 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  15. Signal & background for 2 fb-1 We separate b-bbar background in 2 categories : Same and Opposite sign, assuming that there is as many events in the 2 categories. Assume εL0 = 0.36 for the background (estimated on the preselected events) Apply the L0 prescription to the signal. Assume rB=0.25 for computing Opposite sign signal events yields Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  16. Conclusions and prospects • No B0-B0bar background remains with a annual signal yield of • 2200 events, B/S < 0.4 @ 90%CL and Bpeak/S negligible in SS • 130 events, B/S < 6 @ 90%CL and Bpeak/S ~ 0.2 in OS • New peaking background (BS0bar->D0K*0) identified (in the opposite sign) wrt to the current draft note on B0->D0(hh)K*0 studies • Manageable for Kπ or Kπππ • What about Kππ0 ? (D0 mass constraint ) • One B0->D+(K+K*0)π- additional candidate seen if cut on cosTheta(D0) is loose (>0) • As explained in Jacopo & Stefania’s note, should be limited using a veto on the (K+K*0) invariant mass. • Next steps : • Have a look to the B0->D+(K+K*0)π- • Toy study for γ measurement with Kπ • Need signal events for other channels (Kππ0 & Kπππ) • More detailed look at the peaking bg for Kππ0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  17. Backup slides • All possible cuts Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  18. PT cuts on the D0 Daughters Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  19. P cuts on the D0 Daughters Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  20. IPs cuts on the D0 Daughters Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  21. ΔKπln(Lhood) cuts on the D0 Daughters Only events with particle which is not a true Kaon for bg Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  22. PT cuts on the K*0 Daughters Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  23. P cuts on the K*0 Daughters Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  24. IPs cuts on the K*0 Daughters Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  25. ΔKπln(Lhood) cuts on the K*0 Daughters Only events with particle which is not a true Kaon for bg Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  26. Σln(PT) & Σln(IPs) comb. cuts Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  27. PT & P cuts on the D0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  28. IPs wrt B & IPs wrt PV cuts on the D0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  29. (FDD0-FDB0)s & Fs cuts on the D0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  30. χ²/Ndof & cosθcuts on the D0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  31. PT & P cuts on the K*0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  32. IPs cuts on the K*0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  33. χ²/Ndof & Fs cuts on the K*0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  34. Angular cuts : cosθ* Asymmetry due to the cuts (symmetric) in the kinematic of K* daughters (confirmed by playing on the cut values on the truth) almost all of the Kaons are kept Slow pions are lost Remove the central part where no signal is expected Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  35. IPs & χ²/Ndof cuts on the B0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

  36. FDs & cosθ cuts on the B0 Gamma from trees meeting - Aurélien MARTENS & Marie-Hélène SCHUNE

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