1. B physics at Belle Koji Hara (Nagoya University) Workshop "New Developments of Flavor Physics" 2009 March 9-10, 2009 New results of tauonic B decays B   and  B  D  New results of tauonic B decays B   and  B  D 

2. KEKB & Belle e + source Ares RF cavity Belle detector SCC RF(HER) ARES(LER) e - (8.0GeV) × e + (3.5GeV) ⇒  (4S) → BB ⇒ Lorentz boost:  = 0.425 Finite crossing angle ~11mrad ×2 Operation since 1999. L peak = 1.71x10 34 cm -2 s -1 2 Total:895 fb -1  (4S):~720 fb -1  (5S): ~52.6fb -1  (3S): 2.9 fb -1  (2S):7.1fb -1  (1S):5.7fb -1 Y b scan:8.1fb -1 Off-peak: ~83 fb -1 Total:895 fb -1  (4S):~720 fb -1  (5S): ~52.6fb -1  (3S): 2.9 fb -1  (2S):7.1fb -1  (1S):5.7fb -1 Y b scan:8.1fb -1 Off-peak: ~83 fb -1

3. 3 Belle Detector 4 lyr DSSD He/C 2 H 6 Extreme forward calorimeter

4. Leptonic decays proceed through W boson annihilation in the Standard Model Decay rate simply related to B meson decay constant f B and |V ub | Charged Higgs contribution enhance/reduce the Br [Wei-Shu Hou Phys. Rev. D48, 2342 (1993)] CP Violation may be sensitive to “unparticle” physics [ R. Zwicky, Phys.Rev.D77036004(2008), C.-S. Huang and X.-H. Wu, Phys.Rev.D77,075014(2008)] 4 B +     Introduction  bubu W/H 

5. 5 B   Analysis Concepts Require no particle remain after removing products of tagging B and the particle(s) from B   decay Possible only in B factory More than 2 neutrinos appear in B   decay Tagging side : Semileptonic or Hadronic B Decay Signal side : Detect  daughter particle(s)  (4S) B-B- B+B+  e+e+  e B +  + ,  +  e + e  B-XB-X Most powerful discriminant variable: Extra calorimeter energy E ECL

6. 6 Belle Hadronic B tag (449x10 6 BB pairs) [PRL 97, 251802 (2006)] ◦ 3.5  evidence B (B   )=[1.79 (stat) (syst) ] x 10 -4 BaBar (383 x 10 6 BB pairs) [PRD 77, 011107(R) (2008)], [PRD 76, 052002 (2007)] ◦ Hadronic B Tag ◦ Semileptonic (B  Dl  X) Tag X: ,  0, not reconstructed explicitly ◦ 2.6  excess B (B   )= [ 1.2±0.4(stat)±0.3(bkg)±0.2(syst)]×10 -4 Previous B +   + Measurements +0.56 +0.46 -0.49 -0.51 New Belle Result with D (*) l tag using 657M BB pairs  Need more statistics to establish B +    Decay Belle Hadronic BaBar Dl X BaBar Hadronic B =1x10 -3 Signal B =3x10 -3 Signal

7. 7 Signal Selection Concept Though Br(B  D (*) l )  is large (~17%), S/N is expected to be worse than S/N of hadronic B tags.  We only use clean decay modes with high Br x . Tagging Side ◦ B -  D* 0 l +  D 0 l D *0  D 0  0, D 0   D 0  K -  +,K -      , K -     ◦ Reconstruct D* 0 l  explicitly   prevent  additional    from  contaminating E ECL Signal Side 1 prong decay ◦ B +      e, ,  Require No additional charged tracks or  

8. 8 Tagging side ◦ Identified using a kinematic relation Optimized to maximize in E ECL <0.2 GeV ◦ separately for   l and  modes Signal side ◦ N sig extracted from E ECL ◦ Clear Signal and BG separation expected Selection Criteria signal ( B =1.79x10 -4 ) E ECL (GeV) Events / 0.05 GeV D*l tag,    MC expectation BG + Data + BG D*l tag,   l + Data + BG

9. Semileptonic Tag B   Result [arXiv: 0809.3834, BELLE-CONF-0840] 3.8 σ significance including systematics. Confirmation of previous Belle result with hadronic tags (more precise) Above SM expectation, discrepancy ~1.6 σ 9 (CKMfitter 2008 prediction) Dominant systematic error for B (B   ): BG MC Statistics (12%), Tagging Efficiency(12%) Peaking BG Uncertainty (8%)

10. 10 Determination of f B Product of B meson decay constant f B and CKM matrix element |V ub | Using |V ub | = (4.47±0.30)×10 -3 from Belle B  X u l  inclusive [Belle preliminary, CKM2008] f B = 216  22 MeV (an unquenched lattice calc.) [HPQCD, Phys. Rev. Lett. 95, 212001 (2005) ]

11. 11 r H =2.11  0.75 Constraint on Charged Higgs 95% C.L.

12. B → D  Introduction Semileptonic decay sensitive to charged Higgs T.Miki, T.Mimuta and M.Tanaka:hep-ph 0109244. 1.Smaller theoretical uncertainty of R(D) For B→τν, There is O(10%) f B uncertainty from lattice QCD ( Ulrich Nierste arXiv:0801.4938.) 2.Large expected Br Compare to B→τν 3.The decay shape of 3 body decay can be used to discriminate W + and H + 4. Sensitive to different vertex B   : H-b-u, B  D  : H-b-c W/H   b c Ratio of  to ,e could be reduced/enhanced significantly 12

13. Previous B → D (*)  Measurements Belle inclusive B tag : 5.2σ observation Belle B→D * τν B→D  was not measured Babar B→D (*) τν Babar full reconstruction tag : 13

14. B  D  Analysis Method Similar to B   analysis Υ(4S) BB e K π νeνe ντντ ντντ Signal Side (B→D  ) Tagging Side (B→Hadronic mode) Require no remaining particles in the event using E ECL Additional discriminant variable: Missing Mass square MM 2 of the event to separate B  Dl  BG (MM 2 ~  ) from signal (MM 2 >  ) 14

15. Tag Side Reconstruction fully reconstruct B 0,B + 657x10 6 BB (Belle preliminary) Total B + →147 modes B 0 →133 modes B+B+ B0B0 Beam constraint Mass : N=6.05x10 5 eff. = 0.18% Purity = 51% N=1.01x10 6 eff. = 0.31% Purity = 58% 15

16. Selection of B → D (*)  D (*) decay modesτ selection No additional charged particles and π 0 remain in the event Extra calorimeter Energy(E ECL ) Select signals using Missing Mass square (MM 2 ) 、 P CM (τ→X) Dτν Selection e,μ with lower momentum orbital -Main background: Semileptonic B decays ( D (*) lν ) -signal -Dlν -D*lν -Other BG -signall -Dlν -D*lν -Other BG -signall -Dlν -D*lν -Other BG E ECL No remaining particles events/0.1GeV -signal -Dlν -D*lν -Other BG MM 2 Separate D (*) lν and signal -signal -Dlν -D*lν -Other BG arbitral 16

17. B → D  Result E ECL MM 2 B + →Dτν Plots are projection in the signal enhance region Observed Clear Signal GeV GeV 2 /c 4 events/0.4GeV 2 /c 4 events/0.1GeV ●data - Dτν - D*τν - BG ●data - Dτν - D*τν - BG (E ECL <0.2GeV)(MM 2 >2.0GeV 2 /c 4 ) E ECL MM 2 B 0 →Dτν GeV GeV 2 /c 4 events/0.4GeV 2 /c 4 events/0.1GeV ●data - Dτν - D*τν - BG ●data - Dτν - D*τν - BG (E ECL <0.2GeV) (MM 2 >2.0GeV 2 /c 4 ) 17 (3.8σ) (2.6σ) First evidence Plots are projection in the signal enhanced region (Belle preliminary)

18. B → D *  Result (Belle preliminary) E ECL MM 2 B 0 →D*τν GeV GeV 2 /c 4 events/0.4GeV 2 /c 4 events/0.1GeV ●data - Dτν - D*τν - BG ●data - Dτν - D*τν - BG (E ECL <0.2GeV)(MM 2 >2.0GeV 2 /c 4 ) Observed Clear Signal Plots are projection in the signal enhanced region E ECL MM 2 B + →D*τν GeV GeV 2 /c 4 events/0.4GeV 2 /c 4 events/0.1GeV ●data - Dτν - D*τν - BG ●data - Dτν - D*τν - BG (E ECL <0.2GeV) (MM 2 >2.0GeV 2 /c 4 ) 18

19. Determination of R(D (*) ) Br(B + →Dτν) = 1.51 ± 0.15 [%] -0.39 -0.19 +0.41 +0.24 Br(B + →D * τν) = 3.04 ± 0.22 [%] -0.66 -0.47 +0.69 +0.40 Br(B 0 →Dτν) = 1.01 ± 0.10[%] -0.41 -0.11 +0.46 +0.13 Br(B 0 →D * τν) = 2.56 ± 0.10[%] -0.66 -0.22 +0.75 +0.31 (first error is stat second is systematic, third is D(*)l  Br error) (preliminary) Deviation from the SM expectation B + →Dτν: 1.6σ B 0 →Dτν: 0.5σ Consistent within errors Branching fraction 19  Working on charged Higgs constraint.

20. Summary New measurement of B   with semileptonic tagging method confirms the evidence obtained by Belle haronic tag. Update of hadronic tagging will also come soon. First B  D  measurement in Belle has been performed. We obtained first evidence of B +  D 0  +  decay. Measurement of tauonic B decays are now well established. They are giving tight constraints on charged Higgs. Future measurements in Super B Factory will be strict tests of new physics beyond the SM. 20

21. 21

22. Specific Luminosity With Crab Crossing @ KEKB 22 22 mrad crossing 3.06 bucket spacing Simulation 22 mrad Simulation head-on Crab Crossing Data Not as high as the expectation of simulation Still need more study to achieve the goal (2x specific luminosity) Crab crossing since January 2007

23. 34th International Conference on High Energy Physics 23 8/1 200 8 For    e  modes ◦ Dominant BG: true D(*)lnu tagged B-decays  looser tagging selection ◦ -2.1<cos  BDL <1.3, -2.6<cos  BD*L <1.2, 0.5<P* l tag <2.5 ◦ P* l sig > 0.3 For    mode ◦ Suppress continuum and combinatorial BG  tighter tagging selection ◦ -1.1<cos  B(*)DL <1.1,1.0<P* l tag <2.2 ◦ 1.0<P*  sig < 2.4 ◦ |cos  thrust | < 0.9 Reconstruction efficiency Including Br of  decay modes and tagging side efficiency ◦  e mode: 6.0 x 10 -4 ◦   mode:3.8 x 10 -4 ◦   mode:4.9 x 10 -4 Selection Criteria and Efficiency

24. 34th International Conference on High Energy Physics 24 8/1 200 8 Systematic Errors of Yield BG PDF Shape +18.1 -17.2 Signal PDF Shape +3.1 -3.2 Br of Peaking BG +6.4 -13.0 Rare B,b  ul,  pair BG +5.9 -5.9 Efficiency Ratio +0.5 -0.6 Total+20.3 -22.3

25. 34th International Conference on High Energy Physics 25 8/1 200 8 Br Systematic Error +(%)-(%) (Error for Efficiency) MC stat0.90.9 PID1.3 1.3 Br of  0.40.4 Tracking1.01.0 Tagging Efficiency11.611.6 Signal Yield13.214.7 N BB 1.41.4 Total 21.222.2

26. Systematic error sourceB + →Dτν[%]B + →D*τν[%] MM 2 shape+9.1/-7.9+10.0/-5.8 E ECL shape+10.6/-7.6+7.0/-9.7 Br(B→D**lν)±0.4+0.8/-0.0 D ⇄ D* cross feed +7.1/-6.9+5.1/-5.3 Br(τ→lνν)±0.3 Total15.7/-12.9+13.2/-15.4 sourceB 0 →Dτν[%]B 0 →D*τν[%] MM 2 shape+6.4/-5.8+5.8/-6.1 E ECL shape+9.0/-7.3+9.8/-5.0 Br(B→D**lν)+4.5/-2.6+0.6/-0.3 D ⇄ D* cross feed +5.8/-6.0+3.5/-3.4 Br(τ→lνν)±0.3 Total+13.3/-11.4+12.0/-8.6