1. Analysis work by: Rachid Ayad Sheldon Stone Jianchun Wang CBX note available: /homes/cleo/sls/ds4pi.ps Status of B  D  (4  )   analysis Jianchun Wang 03/17/00

2. Jianchun (JC) Wang2 Introduction Why study B  D  (4  )  ? B  D  (n  )  (n = 1, 2, 3) Charge multiplicity of hadronic B event ~ 5.3 Channels studied: B  D        , D    D   D    D  K   , K    , K        ) D   D  D  K    ) B  D    D  K   , D   K      )

3. 03/17/00Jianchun (JC) Wang3 Selection Criteria Track: ( slow π only first two) TNG approval Good primary track Impact point (0.005,0.03 for p>0.25, 0.01,0.05 for p<0.25) 3  dE/dX consistence for p<0.9 Photon: | cos  | < 0.707 E9/E25 Not fragment Angcrt > 20  °: (Mass constraint) Multi-bump cut Mass cut: –3.0  to 2.5   : Mass cut: ± 2  Dalitz selection: R<0.7 D: Mass cut: ± 2.5  Momentum dependent σ D*: M D* -M D ± 2.5  cut Event: R 2 < 0.3 B: (beam energy constraint) | cos  B | < 0.8  B 2 (  M D*,  M D,  M  ) signal: |  E B | < 2 , |  M B | < 2  M sideband: 5.203 < M B < 5.257 E sideband: 3  < |  E B | < 2 

4. 03/17/00Jianchun (JC) Wang4 The D         Final State 358  29 543  49 329  41 (a) E B sideband |3 – 5|  (b) E B signal ±2 , fit with fixed sideband shape D  K     DKDK DKDK

5. 03/17/00Jianchun (JC) Wang5 Efficiency estimation  Slow  +  B efficiency as a function of M(4  )  Fit B yield in bins of M(4  ) DKDK

6. 03/17/00Jianchun (JC) Wang6 B (B   D        )  B = (1.72  0.14  0.17)%  Systematic errors ( ~ 10%)  5% for slow  + from D* +  5.4% for   2.4% per charged track  3% on background shape  3% on D* + (2.0%) & D o (2.3%) branching fractions  Fitting procedure, 4  decay mechanism dependence small

7. 03/17/00Jianchun (JC) Wang7 The     Mass Distribution  What are the decay mechanisms for the (4  )  final state?  We first examine the     mass spectrum  2 combinations per event  Three D   modes summed together

8. 03/17/00Jianchun (JC) Wang8 The   Final State  Smaller binning in  mass region shown  R represents the location of event in Dalitz plane, the small R is, the more close it is to center  R < 0.7 used for further study R<1 R<0.7 R<0.5

9. 03/17/00Jianchun (JC) Wang9 The D    Final States  With selection of , the M B plot shows a prominent B peak  Summed over all three modes  N = 137±15 Events/ 2 MeV

10. 03/17/00Jianchun (JC) Wang10 The   Mass Distribution Breit-Wigner: Mass=1416±37  = 402±47 MeV Corrected to: Mass=1432±37  =376±47

11. 03/17/00Jianchun (JC) Wang11 Branching ratios for   &A   B (B °  D    ) = (0.29  0.03  0.03)%  # (B °  D    )  # (B °  D        ) = (15  2)%  # (B °  D  A  )  # (B °  D    )  consistent with 100%

12. 03/17/00Jianchun (JC) Wang12 The D          Final State D   D  mode searched Only consider D  K    mode E B side band (a) and E B signal (b) shown B (B   D        ) = (1.80  0.24  0.20)% 195±26 events

13. 03/17/00Jianchun (JC) Wang13 The D    Final State  The M B plot shows a prominent B peak  25  6 events  B = (0.45  0.10  0.05)%

14. 03/17/00Jianchun (JC) Wang14 The   Mass Distribution The   mass distribution is similar to D* + final state Breit-Wigner fit gives: Mass =1367±75,  = 439±135 MeV

15. 03/17/00Jianchun (JC) Wang15 Angular Distributions For a spin-0 A, the D* &  would be fully polarized Angles  D* (D to D* boost),   (normal of  decay plane to  boost) can be used For spin-1, 2 or higher A, the D* could also be fully polarized Only information is if we can exclude full polarization, then we can rule out spin-0 B  D  A  A      D   D         spin 0 1 s s 1 0 1 0 0 1 0 0 0 helicity 0  2 2 3 0  0 0 3 0 0 0

16. 03/17/00Jianchun (JC) Wang16 Angular Distributions Sum of 3 D  and 1 D  ° modes For spin-0 A, both D* &  are fully polarized Data for  decay angle show that A is not spin-0 Spin-0 MC

17. 03/17/00Jianchun (JC) Wang17 Have Found D   Final States Events/ 2 MeV DD DD

18. 03/17/00Jianchun (JC) Wang18 The   Mass Distribution Events/ 100 MeV DD DD

19. 03/17/00Jianchun (JC) Wang19 Angular Distributions   angle between  in A frame to A boost direction   angle of normal of  decay plane to  boost  angle between planes of A decay and  decay B  D  A  A             spin 0 0 s s 1 0 1 0 0 0 helicity 0 0 0 0 0 0 0 0

20. 03/17/00Jianchun (JC) Wang20 Summary We have seen D        decays and have measured the branching ratio (~1.8%) About 15% of the decays are D    There is an unexpected   enhancement at 1419±33 MeV that is 382 ±44 MeV wide, this resonance is still under study, it can also be a non-qq state, or a mixture of several resonance We discover B  D   modes, and we will try measure J P using this modes