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Search for exclusive two body decays of B →D s * h at Belle

Search for exclusive two body decays of B →D s * h at Belle. Luminda Kulasiri University of Cincinnati. Outline Motivation Results Summary. c. c. s. s. W -. W -. *-. *-. b. D S. D S. b. u. *. *. u. V cs. V cs. V ub. V ub. p +. p 0. B -. d. d. u. u.

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Search for exclusive two body decays of B →D s * h at Belle

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  1. Search for exclusive two body decaysof B→Ds*h at Belle Luminda Kulasiri University of Cincinnati • Outline • Motivation • Results • Summary

  2. c c s s W- W- *- *- b DS DS b u * * u Vcs Vcs Vub Vub p+ p0 B- d d u u Motivation – Ds*+-,Ds*+0 B0 ‘Spectator’ diagram • Clean Measurement for Vub – no penguins • Model Independent • Not yet seen • Sin(21+3)

  3. *+ DS b * Vcb Vud s B0 W s d K- u Motivation – Ds*-K+ • W-exchange first seen in B0→ Ds-K+ (br = (4.61.3) x10-5) • PRL 89, 231804(2002) • Not yet seen • - sensitivity ~ 1X10-5 • - could be seen • Role of the final state interactions • D+-, D00 can turn out to beDs*-K+ • (B. Block et al. PRL 78, 3999, 1997) +1.2 -1.1 W-exchange

  4. Belle Detector KL/µ Detector (KLM) Aerogel Cherenkov cnt. (ACC) Particle ID Uses info. From CDC+ACC+TOF 3.5 GeV e+ CsI Calorimeter TOF counter SC solenoid 8GeV e- Silicon Vertex Detector (SVD) Central Drift Chamber (CDC)

  5. Candidate Selection & Background Suppression Decay Chain B0→ Ds*+-, B0→ Ds*-K+, B+→ Ds*+0 Ds*+→ Ds+ Ds+→ {+, KSK+, K*K+} →K+K-, KS→+-, K*→K+-

  6. Photon Energy (E()) Bg. Signal GeV Candidate Selection & Background Suppression • Mass selections - 3  • PID > 0.6 • M = M(Ds) - M(Ds) • | M- 0.1438| < 0.020 GeV • Helicity angle(θh) – for /K* • Angle between momentum of DSand momentum of K in (K*) frame. • Photon-Ecm()>110 MeV, 0 veto • Pcm(Ds*) < 2.5 GeV |cos(θh)| > 0.3 C.M frame (4S) frame

  7. B candidate, –0.05<E<0.05 GeV for h {, K} –0.10<E<0.05 GeV for h {0} 5.27<Mbc<5.29 GeV/c2 Ebeam = 5.29 GeV Candidate Selection & Background Suppression GeV E Vs Mbc Signal MC GeV/c2 B→Ds*+- (Ds+→+)

  8. qr x (QDS) • qr -flavor info. of the other B; • q = +1/-1 for B0/B0 • 0< r <1; r- tagging quality • QDS- Ds Charge Candidate Selection & Background Suppression Fisher Discriminant – 9 variables • cosine of Thrust Angle • θth – angle bet. thrust axis of B and thrust axis of rest of the event • Fox-Wolfram moments • cos(B) • B - angle between B flight direction and beam axis Signal (10K events) continuum Arbitrary units FD

  9. - Fitting (275 Million BB events) • Fitted distribution M =M(Ds*+) –M(Ds+) -Simultaneous fit for the three Ds modes to Br -binned maximum likelihood • Signal – Gaussian, mean, width fixed (MC) • Bg. – linear shape by fitting data ( sig. region excluded), wide cuts • Significance - Lmax - max. likelihood L(0) – max. likelihood if signal is zero

  10. M and E DS*+- DS*-K+ DS*+0 (2.14 0.81)x10-5 (2.43 1.11)x10-5 (1.64 0.66)x10-5 M E

  11. Yields and Branching fractions(Preliminary)

  12. Systematic Uncertainties • 3 Ds modes – common errors, independent errors separately calculated • Highest errors come from B(Ds→) • MC combines Ds modes Common errors

  13. Systematic Uncertainties Independent Errors (%) separately Br (Ds→) – 25%

  14. Results & Summary preliminary First error – stat. ; Second error = syst. except Br(Ds→) Third error – syst. from Br(Ds→) • We searched for B→Ds*h events using 275 m BB events • We have seen evidence for B→Ds*, B→Ds*K and B→Ds*0

  15. Backup slides

  16. DS*+0 8.1±5.7 evts. DS*-K+ 10.6±4.9 evts. DS*+- 21.4±5.9 evts. Mbc Yield

  17. 4.48.4 evts. 15.15.6 evts. 8.24.7 evts. 19.0±5.7 evts 11.0±4.8 evts 9.4±5.5 evts Yield in M and E DS*+- DS*-K+ DS*+0 M E

  18. Sin(21+3) D* - strong phase c – Cabibbo angle D. Becirevic, Nucl. Phys. Proc. Suppl. 94, 337 (2001)

  19. Asymmetric Collider with, • 8.0 GeV e- x 3.5 GeV e+ • 22 mrad crossing angle • Lpeak = 15.33nb-1s-1 • ∫Ldt ~400 fb-1 • Ecm = 10.58 GeV operates at (4S) resonance e+e-→ (4S) →BB KEKB Accelerator C.M frame (4S) frame

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