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Status report B  D 0 K p 0 decay

Status report B  D 0 K p 0 decay. G.Calderini M.Carpinelli N.Neri BaBar Italia Capri 11 Apr 2003 INFN Pisa. Motivations of the analysis. Possibility to measure the weak g angle. M. Gronau and D. Wyler, Phys. Lett. B 265, 172 (1991).

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Status report B  D 0 K p 0 decay

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  1. Status reportBD0Kp0 decay G.Calderini M.Carpinelli N.Neri BaBar Italia Capri 11 Apr 2003 INFN Pisa

  2. Motivations of the analysis • Possibility to measure the weak g angle. • M. Gronau and D. Wyler, Phys. Lett. B 265, 172 (1991). • Dalitz plot can help solving the 8-fold ambiguity of the g value. • R.Aleksan et al. hep-ph/0209194 (Nov 2002) • Measurement of the branching ratio of non resonant decay. BaBar Italia

  3. Extension to Wyler-Gronau method in B-D0K- decays • Measuring g through amplitude relationship • The decay amplitude varies in the Dalitz plot • The Non Resonant decay is color allowed : • larger interference. BaBar Italia

  4. Measurement of g R.Aleksan et al. hep-ph/0209194 (Nov 2002) • Interference amplitudes for each region i of the Dalitz plot • Relation among the number of measured events in each region i both color allowed for Non Resonant decay BaBar Italia

  5. p0 K+ D0 W K+ B+ W D0 p0 B+ Feynman diagrams (Non Res) • The leading tree diagrams are both color allowed • Interference amplitudes are both large b->c quark transition b->u quark transition leading diagram leading diagram BaBar Italia

  6. MC Sample Releases 10.3.1x SP4 • B+ generic: 24.44 fb-1 • B0 generic: 14.87 fb-1 • ccbar: 7.60 fb-1 • uds: 3.63 fb-1 • signal MC: • D0 K+p0 NR: 3000 Ev • D*0 K+ : 3000 Ev • D0 K*+ : 18000 Ev BaBar Italia

  7. List of candidates Release anal13b • Blist:BchToD0KPi0_Default,BchToD0barKPi0_Default • D0 list: D0ToKPi_Loose into hadronic modes: Kp • K list : GTL • p list : GTL K3p, Kpp0 will be added • D0 into CP modes KK,pp , Ksp0 will be added • K list: GTL • p0list :Pi0ToGGLoose BaBar Italia

  8. Selection cuts • K selection • KMicroVeryTight • plab<2.75GeV • 0 selection • doMass true • plab>0.75GeV • |mp0-mPDG|<3s •  selection • Elab>100MeV • Event shape: • FoxWol < 0.3 • |cos(T)| < 0.75 • |DE|<200MeV • P(B+2)>0.1 • D0 selection • K :KMicroTight • doMass true • P(D02)>0.01 • |mD0-mPDG|<3s BaBar Italia

  9. Event Shape |COS(T)|<0.75 FoxWol<0.3 BaBar Italia

  10. Work in Progress Fisher Discriminant (CLEO): 9 cones + cosB + cosT continuum SIG CLEO Fisher BaBar Italia

  11. D0 Selection probD0>0.01 KMicroTight BaBar Italia

  12. Work in Progress • Added new info in the ntuple: • D0 flight length, beam-spot, primary vertex D0 proper time distribution Time(ps) BaBar Italia

  13. Pi0 Selection Plab>0.75 GeV/c BaBar Italia

  14. Bkg composition E distribution MES distribution The number of events is scaled to 100 fb-1 BaBar Italia

  15. BKG composition • Bch:6 B decay not correctly reconstructed 12 combinatorial bkg events 5 false D0 , 3 false Pi0, 4 other • B0 : 1 B decay not correctly reconstructed 6 combinatorial bkg events 2 false D0, 2 false Pi0, 2 other • ccbar: 5 combinatorial events 1 false Pi0, 4 other B-  D*0 -  D0 0 -0 misid K lost 0 soft BaBar Italia

  16. Multiple candidates We found 1 candidate per event in the 3 sigma [MES,DE] with present selection criteria. • IF multiple candidate event is found we select the best candidate with the minimization of the 2: This criteria in principle does not bias MES, DE distribution. BaBar Italia

  17. Expected number of events • We can estimate the order of magnitude of NR BR assuming it equal to RES one: BR(D0 K*+, K*+ K+p0 )  BR(D0 K+p0 )NR 1-2•10-4 BR(D0 K*+ ) = 6.1 x 10-4 [CLEO] We assume the BR= 1 •10-4 • Efficiencies on signal MC after severe cuts with Kp mode: 7% = 30 events • Adding K3p ,Kpp0 we can expect3times the number of events. BaBar Italia

  18. Work in Progress • Added new modes into the ntuple: • Kp, Kpp0, K3p, KK, pp • SP5 signal MC: • More MC signal NR produced with moose: • 15000 events available (before we had 3000) • Started to write the BAD. • Discovered a bug in the Official Tag Bit for DKPi. Contacted the Breco convener and writing the new sequence for the next reprocessing. • Planning to run on data and MC filtering on an inclusive tag bit: D0 + ntrkLoose>=3 BaBar Italia

  19. Next step • Starting production on a consistent generic MC and DATA sample. • BBbar, continuum , signal, cocktail D(*)K(*) • Run1, Run2 • Optimizing the Fisher discriminant approach. • Optimization of the cuts. • Starting cross checks using DATA-MC comparison. BaBar Italia

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