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B Decays to D s +(*) and D *+

B Decays to D s +(*) and D *+. Submitted papers: BABAR-CONF-00/13 BABAR-CONF-00/06. Ben Brau Massachusetts Institute of Technology On behalf of the B A B AR collaboration. Meeting of the Division of Particles and Fields of the American Physical Society August, 2000. Data Sample:

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B Decays to D s +(*) and D *+

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  1. B Decays to Ds+(*)and D*+ Submitted papers: BABAR-CONF-00/13 BABAR-CONF-00/06 Ben Brau Massachusetts Institute of Technology On behalf of the BABAR collaboration Meeting of the Division of Particles and Fields of the American Physical Society August, 2000

  2. Data Sample: On the (4S) resonance 40 MeV below BB threshold (off resonance) Measurements and data samples : 7.7 fb-1 on resonance (~ 8,700,000 BB) : 1.2 fb-1 off resonance Study of inclusive Ds(*) production in B decays. Measurement of B0Ds(*)+D*- branching fraction with a partial reconstruction technique. Measurement of the branching fractions for the decays B0D*+p-andB0D*+r- : 5.2 fb-1 (~5,900,000 BB) Ben Brau DPF 2000

  3. Physics Motivation These measurements can probe Vub and Vcb and test factorization The BABAR detector Charged particle tracking: Combined Silicon Vertex Tracker and Drift Chamber momentum resolution (dpT/pT) 2 = (0.0015pT) 2 + (0.005) 2 Particle identification: dE/dx in SVT and DCH ; Cherenkov angle in DIRC: 2.5 s kaon-pion separation to 3.5 GeV Photon detection: CsI(Tl) crystal calorimeter Branching fraction measurements Yields and efficiencies Systematic errors Results Introduction Ben Brau DPF 2000

  4. Ds fp Inclusive reconstruction of Ds from B decays K+K- • Selection criteria: • kaon ID • |m(KK)-m(f)| < 8.0 MeV • |cosqH| > 0.3 • Efficiency: 40.5 ± 1.0% Ds f p  Df p (Cabibbo-suppressed) • NDs = 18270 ± 200 • mDs= 1968.5 ± 0.1(stat) MeV • = 5.4 ± 0.1 MeV m(Ds)-m(D) = 98.7 ± 0.2(stat) MeV Ben Brau DPF 2000

  5. Inclusive reconstruction of Ds from B decays Ds momentum spectrum Peterson fragmentaion function ec = (12.50.6)10-2 After continuum subtraction: BF(BDsX) = (11.9  0.3 1.1 3.0 ) 10-2 (uses PDG value of BR(Ds f p)=3.60.9%) PDG 2000 (10.0 2.5) 10-2 Ben Brau DPF 2000

  6. Selection criteria: Eg>50 MeV Veto g from p0 1953<M(fp)<1984 Mev Inclusive reconstruction of Ds* from B decays Ds *  Dsg N(Ds *) = 3029 ± 151 Dm= 143.4 ± 0.3MeV sDm=7.4 ± 0.4 MeV fp K+K- BF(BDs* X ) = (6.8  0.7  0.8  1.7)  10-2 (uses PDG value of BF(Ds f p) = 3.6  0.9% ) Ben Brau DPF 2000

  7. Method: Fully reconstruct Ds(*)+ Partially reconstruct D*- ( )p - B0Ds(*)+D*- Branching Fractions ( ) q p - B0 D*- f Ds(*)+ f ambiguity Ben Brau DPF 2000

  8. B0Ds(*)+D*- Branching Fractions Yield: 195 ± 29 Yield: 628 ± 55 Ds-p missing mass Ds*- p missing mass Ben Brau DPF 2000

  9. B0Ds(*)+D*- Branching Fractions Yield from the missing mass after background subtraction : N(B0Ds+D*-): 628 ± 55N(B0Ds*+D*-):195 ± 29 Efficiency: 32.8 ± 1.8%Efficiency: 7.5 ± 1.5% Feed through from B0Ds*+D*- to Ds+p -: 14.9 ± 1.2% * due to BR(Ds f p)= 3.6 0.9% Ben Brau DPF 2000

  10. Exclusively reconstructed decay chain: B0D*-p+ andB0D*-r+reconstruction BF(D*D0p)= (68.3±1.4)% • BF(D0Kp) = ( 3.83±0.09 )% • Selection criteria: • R2 < 0.5 second Fox-Wolfram moment • Pt(pD* ) > 70 MeV • 2.5s m(Kp) • 2.5s m(Kpp)-m(Kp) • rpp0 • Eg >30MeV, 120 < mgg 150 MeV • 620 < m(pp0) < 920 MeV/c2 ,p0 constrained Ben Brau DPF 2000

  11. ExclusiveBreconstruction Observables for exclusively reconstructed B candidates Define DE: where E*Bis the energy of the B candidate in CMS Beam energy known to high precision (~MeV) Define “energy-substituted B mass”: where p*Bis the momentum of the B candidate in CMS Largely uncorrelated variables Ben Brau DPF 2000

  12. B0 D*-p+ reconstruction s= 18.8±0.9MeV Nev=111 ±12 ±2.5 s Feed down region Efficiency:  = 27.0 ± 1.0 % ±2.5 s Ben Brau DPF 2000

  13. s(mES)== 2.45 0.18 MeV/c2 Observed Yield: 119 11 events Measured BF(B0 D*-p+) L ~ 5.2fb-1 BF (B0 D* -p+) = (3.1  0.3  0.3 ) 10 –3 PDG 2000: BF (B0 D* -p +) = (2.76  0.21) 10 –3 Ben Brau DPF 2000

  14. B0 D*-r +reconstruction s= 40±5 MeV ±2.5 s Efficiency:e= 7.6 ± 0.6 % for D*r e=1.1 ± 0.3 % for D*pp0 ±2.5s A Dalitz analysis of D*pp0 will be performed on the full data sample. Upper limit on the non-resonant contribution by CLEO: < 9% at 90% CL. Ben Brau DPF 2000

  15. Measured BF(B0 D* -r +) s(mES)=3.5 0.3 MeV/c2 Observed Yield: 131 13 evts L~ 5.2 fb-1 BF (B0 D* -r+) = (11.5 1.1  2.5) 10 –3 PDG 2000: BF (B0 D*-r+) = (6.8  3.4) 10 –3 Ben Brau DPF 2000

  16. Exclusive Reconstruction of B decays to charm ( ) 2577±59 B0 2636±56 B± B0D*-p + B0D*-r + B -D*0p - B0D*-a1+ B0D -r + B -D 0p - B0D-p + B0D-a1+ Ben Brau DPF 2000

  17. m+ p- K- p+ m- p- p+ p+ ( ) B0 y(2S)K0s B0D*+p- y(2S)  m+ m- D*+D0p+ K0s p+ p- D0K-p+ Ben Brau DPF 2000

  18. Preliminary results on BR of hadronic B decays to open charm: Conclusions BABAR Preliminary PDG 2000 value Ben Brau DPF 2000

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