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Status of B 0 g a 1 p Analysis

Status of B 0 g a 1 p Analysis. ICPV meeting A.Kibayashi H.Ishino March 8, 2007. Introduction. B 0 →a 1 ± p ∓ decays are sensitive to f 2 BaBar has already measured the B.R. and tCPV parameters PRL 97, 051802 (2006) observation of a1pi signal B.R. = (33.2+-3.8+-3.0) x 10 -6

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Status of B 0 g a 1 p Analysis

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  1. Status of B0ga1p Analysis ICPV meeting A.Kibayashi H.Ishino March 8, 2007

  2. Introduction • B0→a1±p∓ decays are sensitive to f2 • BaBar has already measured the B.R. and tCPV parameters • PRL 97, 051802 (2006) • observation of a1pi signal • B.R. = (33.2+-3.8+-3.0) x 10-6 • hep-ex/0612050 • tCPV analysis • effective f2 (NOT f2!) is measured.

  3. Event selection of B0→a1±p∓, a1±→p±p±p∓ • dr<0.1cm, |dz| < 4cm • eid<0.9, kid<0.4 • flavor tagging and vertexing • 2.2<pbach<2.7 GeV/c • 0.6 < M(a1)< 1.8GeV/c2 • 0.55< M(p+p−) <1.15 GeV/c2 at least one combination of the three pions from the a1 decay • |Dt|<70ps • Charm vetos • 1.86 < M(K−p+p+)<1.88 GeV/c2 for D+p− decays • 3.05< M(p+p−)<3.15 GeV/c2 for J/y K*0 decays • 2.00< M(K−p+p+)<2.05 GeV/c2 for D*+p- decays • |DE|<0.12 GeV, Mbc>5.20 GeV/c2

  4. Analysis procedure • the signal yields from a 3D fit to DE, Mbc and helicity angle distribution. • the helicity angle for discriminating a1p and a2p. • helicity angle definition: the angle between the normal of the a1 decay plane and B direction in the a1 rest frame. • fit parameters: yields of signal, a2p, charm and charmless B decays, continuum, and the DE and Mbc shape parameters of the continuum. a1->3pions L=1 assuming s-wave decay: prim. pion q B

  5. Fitting Results Generic Rare Continuum a1p TM a1p SCF a2pTM a2p SCF

  6. Signal Yield

  7. Branching Fraction Exp7-49 Na1p = 653.43 + 70.55 - 69.15 N(BB) = 534.586  7.044 e = 9.06% (no. falls into our analysis region/no. signal MC generated) Brsub = 0.5, assume 1/2 a1 decay to r0p+, 1/2 r+p0 ePID = 0.906  0.009 (stat)  0.008(syst), for 4 pion final state

  8. Use full recon sample(Exp7-43) Cut -0.15 < DE < -0.05 GeV, Mbc>5.27 GeV/c2 Efficiency from MC = 3.3% B.R. = (2.42  0.05) x10-4 PDG (2.54  0.28) x10-4 Check with B0gD-p+, D-gK+p-p-

  9. Systematic Errorsnot completed yet Need a1 mass fit take e(before lr cut)/e(after lr cut)

  10. Sys. error : Fit Bias GeantMC: from linear fit Sig. in = 653.4 Sig. expected = 628.8 error = 3.8 % ToyMC: Sig. in = 604.7 Sig. out = 604.2 error = 0.1 % total. 3.8 %

  11. Sys. error : dwave • TM helicities differ swave dwave

  12. Sys. error : dwave cont'd • scf DE-Mbc shapes differ dwave swave

  13. Sys. error : dwave cont'd Replace: 1. scf fraction 0.199 g 0.155 (from sig. MC) 2. scf DE-Mbc PDF swave g dwave 3. scf helicity PDF swave g dwave 4. tm helicity PDF swave g dwave => new sig. yield 653.4 g 579.5, 11.3%! Replace one by one... 1. +7.0% 2. -0.1% 3. -0.3% 4. +7.2%

  14. Summery • 50 % BN circulated to the referees • + validity check, sys. error, a1mass fit(?), early next week.

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