1. 16 April 2005 APS 2005 Search for exclusive two body decays of B→D s * h at Belle Luminda Kulasiri University of Cincinnati Outline Motivation Results Summary

2. 16 April 2005 APS 2005 Motivation – D s *+  -,D s *+  0 B-B- c u V ub u u s W-W- b V cs * DSDS *- 00 B0B0 c V ub d u s W-W- b V cs * ++ d DSDS *- ‘Spectator’ diagram Clean Measurement for V ub – no penguins Model Independent Not yet seen Sin(2  1 +  3 )

3. 16 April 2005 APS 2005 Motivation – D s *- K + B0B0 V cb * V ud d b DSDS *+*+ K-K- W s s u W-exchange first seen in B 0 → D s - K + (br = (4.6  1.3) x10 -5 ) PRL 89, 231804(2002) Not yet seen - sensitivity ~ 5X10 -6 - could be seen Role of the final state interactions D +  -, D 0  0 can turn out to be D s *- K + (B. Block et al. PRL 78, 3999, 1997) W-exchange +1.2 -1.1

4. 16 April 2005 APS 2005 KEKB Accelerator Asymmetric Collider with, 8.0 GeV e - x 3.5 GeV e + 22 mrad crossing angle L peak = 15.33 nb -1 s -1 ∫Ldt ~400 fb -1 E cm = 10.58 GeV operates at  (4S) resonance e + e - →  (4S) →BB C.M frame   (4S) frame

5. 16 April 2005 APS 2005 Belle Detector Silicon Vertex Detector (SVD) Central Drift Chamber (CDC) K L /µ Detector (KLM) 8GeV e - 3.5 GeV e + Aerogel Cherenkov cnt. (ACC) CsI Calorimeter TOF counter SC solenoid Particle ID Uses info. From CDC+ACC+TOF

6. 16 April 2005 APS 2005 Candidate Selection & Background Suppression Decay Chain B 0 → D s *+  -, B 0 → D s *- K +, B + → D s *+  0 D s * + → D s +  D s + → {  +, K S K +, K * K + }  →K + K -, K S →  +  -, K * →K +  -

7. 16 April 2005 APS 2005 Candidate Selection & Background Suppression Mass selections -  3  PID > 0.6  M = M(D s  ) - M(D s ) |  M- 0.1438| < 0.020 GeV Helicity angle(θ h ) – for  /K* Angle between momentum of D S and momentum of K in  (K*) frame. Photon-E cm (  )>110 MeV,  0 veto P cm (D s *) < 2.5 GeV Photon Energy (E  ) Signal Bg. GeV |cos(θ h )| > 0.3

8. 16 April 2005 APS 2005 Candidate Selection & Background Suppression B candidate, –0.05<  E<0.05 GeV for h  { , K} –0.10<  E<0.05 GeV for h  {  0 } 5.27<M bc <5.29 GeV/c 2 E beam = 5.29 GeV GeV GeV/c 2 Signal MC B→D s *+  - (D s + →  + )  E Vs M bc

9. 16 April 2005 APS 2005 Candidate Selection & Background Suppression Fisher Discriminant – 9 variables cosine of Thrust Angle θ th – angle bet. thrust axis of B and thrust axis of rest of the event Fox-Wolfram moments qr x (Q DS ) qr -flavor info. of the other B; q = +1/-1 for B 0 /B 0 0< r <1; r- tagging quality Q DS - D s Charge cos(  B )  B - angle between B flight direction and beam axis FD Arbitrary units continuum Signal (10K events)

10. 16 April 2005 APS 2005 Fitting (275 Million BB events) Fitted distribution  M =M(D s *+ ) –M(D s + ) -Simultaneous fit for the three D s modes to Br -binned maximum likelihood Signal – Gaussian, mean, width fixed (MC) Bg. – linear shape by fitting data ( sig. region excluded), wide cuts Significance - - L max - max. likelihood L(0) – max. likelihood if signal is zero

11. 16 April 2005 APS 2005  M and  E (1.64  0.66)x10 -5 (2.14  0.81)x10 -5 (2.43  1.11)x10 -5 MM EE D S *+  - D S *- K + D S *+  0

12. 16 April 2005 APS 2005 Yields and Branching fractions (Preliminary) ModeRec. eff(%)signalBr(X10 -5 ) D s *+  -  + K s K + K * K + 8.47  0.29 3.73  0.68 3.05  0.36 5.49  3.17 7.32  3.44 4.18  2.68 1.41  0.89 6.16  3.55 2.61  1.70 Combined 2.14  0.81(4.7  ) D s *- K +  + K s K + K * K + 6.47  0.24 3.14  0.58 5.20  0.59 3.90  2.44 2.19  1.97 4.04  3.34 1.31  0.89 2.19  2.10 1.36  1.20 combined 1.64  0.66(4.5  ) D s *+  0  + K s K + K * K + 3.85  0.23 2.45  0.46 3.07  0.39 4.17  2.44 2.25  2.79 0.90  3.39 2.36  1.51 2.89  3.71 0.51  1.95 Combined 2.43  1.11(4.0  )

13. 16 April 2005 APS 2005 Systematic Uncertainties 3 D s modes – common errors, independent errors separately calculated Highest errors come from B(D s →  ) MC combines D s modes  /  0 recon. Br(D s *→D s  ) N BB total common except (br(D s  →   )) 5% 3% 1% 5.92% Common errors

14. 16 April 2005 APS 2005 Systematic Uncertainties Br(D s ) /Br(D s  →   ) Br(sub D s ) K s Fitting MC stat. Tracking PID Common Total D s *+  -  + K s K + K * K + 0.00 22.2 9.1 1.4 0.4 0.2 - 3.0 - 8.20 4.5 3.4 2.9 5.9 12.04 D s *- K +  + K s K + K * K + 0.00 22.2 9.1 1.4 0.4 0.2 - 3.0 - 9.40 6.1 4.5 3.9 5.9 14.25 D s *+  0  + K s K + K * K + 0.00 22.2 9.1 1.4 0.4 0.2 - 3.0 - 14.9 8.1 4.4 4.0 5.9 17.34 Independent Errors (%) separately Br (D s  →   ) – 25%

15. 16 April 2005 APS 2005 Results & Summary We searched for B→D s * h events using 275 m BB events We have seen evidence for B→D s * , B→D s * K and B→D s *  0 preliminary First error – stat. ; Second error = syst. except Br(D s  →   ) Third error – syst. from Br(D s  →   )

16. 16 April 2005 APS 2005 Backup slides

17. 16 April 2005 APS 2005 M bc Yield D S * - K + 10.6±4.9 evts. D S * +  - 21.4±5.9 evts. D S * +  0 8.1±5.7 evts.

18. 16 April 2005 APS 2005 Yield in  M and  E 11.0±4.8 evts 19.0±5.7 evts 9.4±5.5 evts MM EE 4.4  8.4 evts. 15.1  5.6 evts. 8.2  4.7 evts. D S *+  - D S *- K + D S *+  0

19. 16 April 2005 APS 2005 Sin(2  1 +  3 )  D*  - strong phase  c – Cabibbo angle D. Becirevic, Nucl. Phys. Proc. Suppl. 94, 337 (2001)