1. Belle 2003 Summer Results 1 Recent Belle Results on CP Violation in B 0   Ks Y.Sakai KEK

2. Belle 2003 Summer Results 2 Outline LP2003: Belle B 0   Ks “sin2  1 ” =  0.96  0.50 +0.09  0.11 - experimental some detail - Introduction KEKB and Belle b  ccs (Golden modes) sin2  1 b  s Penguin “sin2  1 ” - [hep-ex/0308035, submitted to PRL]

3. Belle 2003 Summer Results 3 1) Discover/Establish CPV 2) Establish KM scheme of CPV Precise Measurement  CKM constraints other angles(  2,  3 ) & DCPV 3) find evidence Beyond SM 2001 summer ! (main) Goal of B-factory  1 ~established on going This Talk

4. Belle 2003 Summer Results 4 Kobayasi-Maskawa Scheme CPV : due to a complex phase in the quark mixing matrix CKM matrix Wolfenstein representation Important element of SM  1   2   3  V td V tb V cd V cb V ud V ub * * * Unitarity triangle

5. Belle 2003 Summer Results 5 Mixing Induced CPV (b  ccs) ｆ ｃｐ B0B0 B0B0 mixing = B0B0 B0B0 ｆ ｃｐ B0B0 B0B0 B0B0 V cb V tb V*V* V*V* J/  KSKS  td V cs * mixing KSKS Sanda Bigi Carter ) fB()B( ) fB() fB( A CP 0 d 0 d 0 d 0 d    f = -  f sin2  1 sin(  m  t)  1 (   3 (   2 (  - decay

6. Belle 2003 Summer Results 6 CP Violation in b  sqq - A CP = S sin(  m  t) + A cos (  m  t) 2Im   S =       A = qpqp =  f AAAA  + + New Physics with New Phase S bs  S bc, A can  0 S bs = sin2  1, A=0 SM: b  s Penguin phase = (cc) K 0 - Mixing induced CPVDirect CPV tstb VV  “b  ccs: sin2  1 ” (SM reference) deviation

7. Belle 2003 Summer Results 7 KEKB asymmetric e + e  collider Two separate rings e  (HER) : 8.0 GeV e + (LER) : 3.5 GeV E CM : 10.58 GeV at  (4S) ±11 mrad crossing angle Luminosity: (achieved) 1.06 x 10 34 cm -2 s -1 Current: 1.5 / 1.1A (LER HER) Bemsize:  y  3  m  x  100  m  = 0.425 World highest Lum. Machine !

8. Belle 2003 Summer Results 8 KEKB accelerator

9. Belle 2003 Summer Results 9 Peak Luminosity

10. Belle 2003 Summer Results 10 579 pb -1 /day Integrated luminosity/day Total accumulated luminosity 158 fb -1 140 fb -1 on Y(4S) 15 fb -1 off Y(4S) 152M BB - (2003 summer) Integrated Luminosity & Data

11. Belle 2003 Summer Results 11 Belle Collaboration

12. Belle 2003 Summer Results 12 The Belle Collaboration Aomori U. BINP Chiba U. Chuo U. U. of Cincinnati Frankfurt U. Gyeongsang Nat’l U. U. of Hawaii Hiroshima Tech. IHEP, Beijing ITEP Kanagawa U. KEK Korea U. Krakow Inst. of Nucl.Phys. Kyoto U. Kyungpook National U. U. of Lausanne Jozef Stefan Inst. U. of Maribor U. of Melbourne Nagoya U. Nara Women’s U. National Central U. Nat’l Kaoshiung Normal U. Nat’l Lien-Ho Inst. of Tech. Nat’l Taiwan U. Nihon Dental College Niigata U. Osaka U. Osaka City U. Panjab U. Peking U. Princeton U. Riken Saga U. USTC Seoul National U. Sungkyunkwan U. U. of Sydney Tata Institute Toho U. Tohoku U. Tohuku Gakuin U. U. of Tokyo Tokyo Inst. of Tech. Tokyo Metropolitan U. Tokyo U. of A and T. Toyama Nat’l College U. of Tsukuba Utkal U. IHEP, Vienna VPI Yokkaichi U. Yonsei U.  institutes, ~300 members

13. Belle 2003 Summer Results 13 Belle Detector  / K L detection 14/15 lyr. RPC+Fe C entral D rift C hamber small cell +He/C 2 H 5 CsI(Tl) 16X 0 Aerogel Cherenkov cnt. n=1.015~1.030 Si vtx. det. 3 lyr. DSSD TOF conter SC solenoid 1.5T 8 GeV e  3.5 GeV e 

14. Belle 2003 Summer Results 14 Detector Performance Vertex: impact param.  xy,z  m  @1GeV Tracking: CDC+SVD  pt /p t =0.19p t (+) 0.34 % EM calorimetry:  E /E~1.8% @ E=1GeV PID: ACC+TOF+dE/dx(CDC) [  =95ps,  =6.9% for MIPS] K-id:  ~90%,  ~6% upto 3 GeV e-id: ECL +PID  >90%,  ~0.3% (>1GeV)  -id: KLM  >90%,  1GeV)  =efficiency,  =fake rate] Good Resolutions & Good PID

15. Belle 2003 Summer Results 15 CPV Measurement Flavor-tag (B 0 or B 0 ?) J/  (  ’) KSKS ee ee zz t=0 f CP Vertexing Reconstruction Extract CPV fit same analysis methods for (cc)K 0 and Penguin modes - B0B0 B0B0 B 0 -tag  t   z/c 

16. Belle 2003 Summer Results 16 B-meson Reconstruction Energy difference: Beam-constrained mass:  Utilize special Kinematics at Y(4S)

17. Belle 2003 Summer Results 17 sin2  1 : CP samples 2911 events are used in the fit (CP=-1) 140 fb -1, 152 x 10 6 BB pairs 81% CP=+1 -

18. Belle 2003 Summer Results 18 B 0  J/  K L p B * (cms) 2332 events (purity = 0.60) J/  K L 1399±67 signal   KLKLKLKL K L direction + 2-body decay kinematics

19. Belle 2003 Summer Results 19 Flavor Tagging ｂ ｄ ー B0B0 ｓ u ｃ ー  K+K+ d ー ー W+W+ l+l+ W-W- l-l- ++ ー D*D* -- slow High-p (primary), low-p (secondary) leptons Strangeness (b  c  s) Fast , slow  2-stage Multi-dim. Likelihood based method (incl. correlations) ー utilize all available info.

20. Belle 2003 Summer Results 20 2-stage Likelihood-based Flavor Tagging  KLepton Q, p*, p miss, e-id,.. PDF (Lookup Table) q.r = N B - N B N B + N B q =   B tag q =   B tag r=quality(0-1) q.r Event-level LH Lookup Table  6 r-regions (6 tag categories) x2(B 0,B 0 ) Track-level LH ss (MC) - 

21. Belle 2003 Summer Results 21 Flavor Tagging Performance (OF-SF)/(OF+SF) ~(1-2 w)cos(Δm t) 12 r-bins, 6 divisions in r. B 0 and B 0 tags treated separately. _ B 0 –B 0 mixing _ Efficiency > 99.5%  effective = 28.7  0.5% determined by data B 0  D*l

22. Belle 2003 Summer Results 22  z: Vertex Reconstruction  (4S ) l    B CP zz l D K  B tag J/J/ l  KSKS   z CP –Use primary tracks from B CP z tag –Use all tag-side tracks (not off-vtx) z CP –Use primary tracks from B CP z tag –Use all tag-side tracks (not off-vtx) SVD hits are required ( ) z t c     =  (z CP ) ~ 75  m,  (z tag ) ~ 140  m IP constrained fit ( Resol. params: lifetime fit to control samples)

23. Belle 2003 Summer Results 23 PDF for CP fit     'td)'tt(R P(1-f ) PfL BGsig i  tmsin2 )  21(q1 2 e P 1f B t sig B  q     ) ] R BG t()1( 2 e fP BG t GB       R : resolution function free parameters: S, (A) only !  [ f (M bc,  E) 2D fit M bc EE Unbinned Max. Likelihood Fit J/  Ks + P pol

24. Belle 2003 Summer Results 24 sin2  1 Fit Result 5417 events @ 140 fb  1 consistent with no direct CPV (78 fb -1 :0.719±0.074±0.035) Preliminary

25. Belle 2003 Summer Results 25 Compare CP odd and CP even CP=  1 CP=+1 sin2  1 0.73  0.06 0.80  0.13 (statistical errors only) opposite! (all r-bins)

26. Belle 2003 Summer Results 26 Systematic Uncertainty SourcesError Flavor tag0.014 Vertex reconstruction0.013 Signal fraction (J/  K L ) 0.012 Signal fraction (other)0.007  t resolution function 0.008 Fit bias0.008 B tag decay interference0.008  t background distribution < 0.005  m B,  B < 0.005 Total0.028 Small uncertainty in analysis procedure Small uncertainty in analysis procedure stat err. = 0.057

27. Belle 2003 Summer Results 27 Current Results for sin2  1 sin2  1 (Belle 2003,140 fb -1 ) =0.733±0.057±0.028 sin2  1 (BaBar 2002, 81 fb -1 ) =0.741±0.067±0.033 sin2  1 (New 2003 World Av.) = 0.736±0.049 (no updated yet) [PDG2003: 0.731 ± 0.056] Good SM reference

28. Belle 2003 Summer Results 28  b  s Penguin Decays mode Br(K 0 : x10 -6 )* B 0   Ks 7.8  1.1 theoretically clean B 0   ’Ks 65.2  6.0 unexpected large Br B 0  K + K - Ks 25.2  2.7 CP=+1: 1.03  0.15  0.05 cf) B 0  J/  Ks 850  50 [* HFAG LP03 averages]  + e.g.) squark penguin much smaller than Golden mode

29. Belle 2003 Summer Results 29 Continuum Suppression e+e+ e-e- e+e+ e-e- qq Signal B Other B Dominant Background Continuum Jet-like BB event spherical To suppress. use characteristic Event shape random combinations in e + e  → qq continuum events.  

30. Belle 2003 Summer Results 30 Continuum Suppression (2) SFW = Fisher modified Fox-Wolflam moments (6) cos  B : direction of B flight L S /(L s + L B ) Likelihood Ratio signal continuum (optimized in each r-bin)

31. Belle 2003 Summer Results 31 B 0 →  K S  K  K       B 0  K  K  K S (K  K   ) B 0   ’K S        Penguin: B 0  ’K S,  K S,K  K  K S N sig (  K S )=68(64%) N sig (K  K  K S )= N sig (  ’K S )=244(58%) CP=even 103  16% ∫L dt = 140 fb -1 106 ev 361 ev 421 ev 199(55%)

32. Belle 2003 Summer Results 32 Fit Results Fit sin2  1 B0  KSB0  KS B0  KKKSB0  KKKS B 0   ’K S  f S A

33. Belle 2003 Summer Results 33 Comparison of 78/140fb -1 (2002/2003)

34. Belle 2003 Summer Results 34 Systematic Errors

35. Belle 2003 Summer Results 35 B  φ K S : Systematic Effect of Backgrounds with CPV CP in the background: (7.2±1.7)% K + K - K S : (1.6 )% f 0 K S +1.9  1.5 (measured) Correlation between A and S ? A =  0.15 ±0.29±0.07 If A is fixed to zero,  f S =  0.99±0.50 Effects: included in the systematic error (CP=+1) S: +0.001/  0.084  Ks K + K - mass ±10MeV [cf) K  K  K S :  0.54 ± 0.24,  K S :  0.43 ± 0.27]

36. Belle 2003 Summer Results 36  Ks :  t distribution Poor tags Good tags

37. Belle 2003 Summer Results 37  Ks : sideband asymmetry 

38. Belle 2003 Summer Results 38 B ±  φ K ± Control Sample No sin-like asymmetry. [ cf) B    K  :  f S =  0.10 ± 0.14 ] fSfS

39. Belle 2003 Summer Results 39 Lifetime Check consistent with PDG values  = 1.671  0.018 BB  = 1.537  0.015 B0B0

40. Belle 2003 Summer Results 40 Toy MC Check :  Ks [other modes are also reasonable]

41. Belle 2003 Summer Results 41 Significance B 0  K  K  K S,  ´K S Consistent with sin2  1. B 0   K S – Likelihood curve 3.5  deviation from 0.731 (PDG2003) sin2  1

42. Belle 2003 Summer Results 42 Significance (2) 99.972% Toy MC generated S,A=(+0.731,0)  0.96 Full Feldman-Cousins (includes sys. errors)

43. Belle 2003 Summer Results 43 BaBar 2003:CPV in B  φ K S 110 fb -1 (A=0.38±0.37±0.12) sin2φ 1eff (φ K S ) = +0.45 ± 0.43 ±0.07 sin2φ 1eff (φ K S ) = -0.18±0.51±0.09 ] [ 81 fb -1 : 70±9 (~2.1  deviation between Belle)

44. Belle 2003 Summer Results 44 “sin2  1 ” Summary “SM” Av =  0.14±0.33 (2.6  away)

45. Belle 2003 Summer Results 45 Summary b  ccd (Golden modes) sin2  1 = 0.733  0.057  0.028 (152M BB) 0.736  0.049 (new world average) precision measurement Good agreement with SM  SM reference b  s Penguin “sin2  1 ” (152M BB) B 0   Ks : “sin2  1 ” =  0.96  0.50 3.5  deviation from SM sin2  1 Hint for New Physics ? +0.09  0.11 More data Exitement ! (  Super B-factory)

46. Belle 2003 Summer Results 46 History… B   Ks ?

47. Belle 2003 Summer Results 47 Future Prospect Luminosity(fb -1 ) Total Err. of S  K S K + K - K S  ’ K S sin2  1 ( ｃｃ K 0 ) now (140fb -1 )

48. Belle 2003 Summer Results 48 Backup

49. Belle 2003 Summer Results 49 CP of K + K - Ks K-K- KSKS B0B0 J=0 L =l l decay CP = +1 K+K+ C=(-1) P=(-1) CP = (-1) l CP = +1 l = odd l = even Isospin symmetry + K + ~100% CP+!     1.03  0.15 (stat)  0.05 (sys) [hep-ex/0307082, submitted to PRD]

50. Belle 2003 Summer Results 50 B  K + K - K + : b  u contribution b  s Penguin BK+K-K+BK+K-K+ BK+K-+BK+K-+ b  u Tree b  d Penguin < 0.017 < 6.3 ( x10 -6 ) 29.5  1.8 (HFAG LP03) [hep-ex/0307082, submitted to PRD]

51. Belle 2003 Summer Results 51 B0B0 d d KSKS dd d d B0B0 B0B0 KSKS KSKS B 0  ’K S diagrams All give sin2  1 (OK)  ｂ ｄ u u ｄ ｓ ー ー ー B0B0 ’’ Ks V cs ー V ub b  u tree pollution small B0B0 KSKS d d

52. Belle 2003 Summer Results 52 Selection Criteria B 0   K S :   K + K , K S      (  =27.7%) –Minimal kaon-identification requirements. –Belle standard K S selection. –| M(KK)  M(  | < 10MeV/c 2 (mass resolution = 3.6 MeV/c 2 ). –| p  | in CMS > 2.0 GeV/c. –|  E | < 60MeV, 5.27 < M bc < 5.29 GeV/c 2. B 0      K S (  =15.7%) –More stringent kaon-identification requirements. –Veto for ,  D 0,  c0, and J/   K  K  and D +  K  K S. –|  E | < 40 MeV, 5.27 < M bc < 5.29 GeV/c 2. B 0   ´K S :1)  ´  ,    +   (  =15.7%) 2)  ´   +  ,    (  =17.7%) –|  E| < 60MeV (  ´   ;  100 <  E < +80 MeV (  ´      ) 5.27 < M bc < 5.29 GeV/c 2

53. Belle 2003 Summer Results 53  K Signals

54. Belle 2003 Summer Results 54  ’K Signals

55. Belle 2003 Summer Results 55 K + K  Ks Signals

56. Belle 2003 Summer Results 56 sin2  1 for Subsamples

57. Belle 2003 Summer Results 57 Resolution Function Pdf(  t) = P sig R sig + P BG + P OL R sig = R det R NP R Kin R det Multipul track: single Gaussian   z = (s 0 + s 1  Zvtx (rec. and asoc. vtx)  = (1/n)  (z vtx -z trk ) 2 /  Ztrk 2 (goodness of fit) Single track: two Gaussians (s main, s tail, f tail,) R NP : non-primary particle effect Asymmetric exponential (  BG depends on   z ) R Kin : effect of B motion in CMS Analytic formula as a function of cos  Brec : detector resolution (P OL : outlier, Gaussian) (R det(CP) R det(tag) )

58. Belle 2003 Summer Results 58 Lifetime Fit Control samples B 0 : 124K ev D*l, J/  K*,D (*)+  - B  : 57K ev J/  K -,D 0  -  = 1.533  0.008(stat) ps  = 1.634  0.011(stat) ps BB B0B0 PDG2003: 1.537  0.015 ps PDG2003: 1.671  0.018 ps Determine Resol. params

59. Belle 2003 Summer Results 59 Upgrade : SVD2.0 Better impact parameter resolution: R bp = 2.0 cm  1.5 cm Larger acceptance: 23º<  <139º  17º<  <150º More radiation hardness : 1 MRad  >20 MRad SVD1.4 SVD2.0 23º<  <139º 17º<  <150º Larger