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Measurements of  at B A B AR and B ELLE

Measurements of  at B A B AR and B ELLE Max Baak, NIKHEF on behalf of the B A B AR and BELLE Collaborations Beauty 2005, Assisi. Outline. Measurements of  using B  D (*) K (*) GLW Method ADS Method D 0 Dalitz Method (GGSZ)

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Measurements of  at B A B AR and B ELLE

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  1. Measurements of  at BABAR and BELLE Max Baak, NIKHEFon behalf of the BABAR and BELLE Collaborations Beauty 2005, Assisi

  2. Outline • Measurements of  using BD(*)K(*) • GLW Method • ADS Method • D0 Dalitz Method (GGSZ) • Measurements of sin(2+) using B0D(*) / • Outlook  

  3.  in the Unitarity Triangle (,) CKM Unitarity Triangle (0,0) (1,0) • Expect  ≈ (60 ± 6)° from SM fit to: sin2, |Vub/Vcb|, md, ms, k • Most challenging angle to measure experimentally: • Low branching fractions • Low reconstruction efficiencies • Small interferences • The only solution with  is statistics

  4.  from B- D(*) K- • Access  via interference between B-  D(*)0 K- and B-  D(*)0 K-. Color-allowed b c amplitude Color-suppressed b u amplitude u u  f K– D0 Vus* s Vcs* c W – b b c W – amplitude ratio rBrelative weak phase and strong phase B s Vub K– B–  f B– D0 Vcb u u • Reconstruct D in final state f accessible both to D0 and D0. • Will discuss 3 methods with different final states f in this talk: • GLWGronau – London – Wyler 2. ADSAtwood – Dunietz – Soni 3. GGSZGiri – Grossman – Soffer – Zupan Belle collaboration Critical parameter rB~ 0.1 for sensitivity to  ! • In order to determine rB, , B simultaneously, need to measure as many D(*)0 modes as possible.

  5. Preface: Analysis Techniques 1. B-meson identification 2. Combinatoric e+e–  qq bkg suppression mES E = EB*–E*beam data MC E Event topological variables combined in Neural Network or Fisher discriminant 4. Time-dependent measurements (only B0/B0) 3. K/ separation (Cherenkov angle / TOF) – K– BaBar D0 Excellent separation between 1.5 and 4 GeV/c B0 KS tag side e+ e+ B0 lepton Coherent B0B0 production from (4S) boost  ≈ 0.55/0.42 allows t measurement

  6. GLW Method • Reconstruct D meson in CP-eigenstates (accessible to D0 and D0) • Theoretically very clean (“golden mode”) to determine  • Relatively large BFs (10-5), small CP asymmetry  3 Independent measurements (A+R+ = -A-R-) and 3 unknowns (rB, , B) CP even modes: K+K-, +- CP odd modes: KS0, KS, KS, KS Phys. Lett. B253, 483 (1991); Phys. Lett. B265, 172 (1991); Phys. Lett. B557, 198 (2003)

  7. GLW Method Results PRL92,202002, 214M BB 95  15 events 76  13 events 114  21 events 167  21 events B-CONF-0443, 275M BB

  8. GLW Results Combined PRD71,031102, 123 M BB No useful constraints on  yet due to small branching ratios and limited statistics. PRL92,202002, 214M BB B-CONF-0443, 275M BB B-CONF-0443, 275M BB − 0.09 − 0.04 hep-ex/0408069, 227M BB hep-ex/0307074, 96M BB − 0.14 − 0.33 (0.15±0.10) x (ACP--ACP+) (*) CP-even pollution in the CP-odd channels

  9. ADS Method Phys. Rev. Lett. 78, 3257 (1997) • Reconstruct D in final state K - small BF (10-6) • Amplitude:  Amplitudes comparable in size  large CP violation • Count B candidates with opposite sign kaons! suppressed favored B– D0 K– B– D0 K– K+– K+– interference favored suppressed PDG, Phys.Lett. B592, 1 (2004) D : D decay strong phase unknown. Scan over all values. 2 observables vs 3 unknowns: rB, , B

  10. ADS Method Results No signal observed! BABAR: 227M BB 227 M BB 275 M BB PRL 94, 091601 preliminary B+ D0K+ B+ D0K+ N = 8.5 +6.0(2.3) N = 4.7 +4.0 −3.2 −5.3 RADS = 0.013+0.011 RADS = 0.023 +0.016 ± 0.001 −0.009 −0.014 AADS = +0.88 +0.77 ± 0.06 –0.62 preliminary B+ [D00]D* K+ BELLE: 275M BB N = −0.2 +1.3 −0.8 RADS = −0.002 +0.010 −0.006 B+ [D0]D* K+ preliminary N = 1.2+2.1 −1.4 RADS = 0.011 +0.018 −0.013 hep-ex/0408028 0 -0.1 0.1 E (GeV)

  11. ADS Method Results The smallness of rB makes the extraction of  with GLW/ADS difficult! 0 < D < 2rd ± 1 48° <  < 73° same, any  RADS # Events 227 M BB hep-ex/0408028 Belle (90% CL) B+ D0K+ RADS = 0.013+0.011 −0.009 275 M BB PRL 94, 091601 BaBar (90% CL) B+ D0K+ RADS = 0.023 +0.016 ± 0.001 −0.014 DK: rB < 0.23D*K: r*B2 < (0.16)2 DK: rB < 0.27 @ 90% C.L. @ 90% C.L. BaBar RADS  1

  12. GGSZ Method Phys. Rev. D68, 054018 (2003) Color-allowed b c amplitude Color-suppressed b u amplitude • Reconstruct Din final state: KS +- (not a CP-eigenstate) • Employs K-K mixing (“cheap” decay-mode: high BF ~2.2x10-5 ) • Final state accessible through many intermediate non-CP states. Need Dalitz analysis to separate resonance interferences! KS u u K– D0 + Vus* s Vcs* - c W – b KS b c W – interference s Vub K– B– B– D0 Vcb + - u u

  13. GGSZ Method • D decay amplitude f consists of sum of many resonances (more on next slide). • Amplitude f parameterized in terms of Dalitz variables m+2 and m-2 • Decay rates  of B+ and B- written as: u u - + d d W W c s c s KS KS D0 D0 + - u u 2 ± = Simultaneous fit to D  KS +- Dalitz planes of B+ and B- to extract rB, , and 

  14. D0 KS+ - Dalitz Model • To extract rB and  need high-precision D decay model f (m+2, m-2) • Obtain f (m+2, m-2) using fit to “tagged” D0 sample:  Use large D*+ D0+ sample. Charge of the pion gives flavor of D. Isobar formalism, no D mixing, no CPV in D decays D*+ D0+, 81.5k events from 91 fb-1, purity 97% hep-ex/0504039 2 = 3824/ 3054 =1.25 K*(892) DCS K*(892) 0(770) 0(770) DCS K*(892) 13 resonances (2 ), 3 DCS partners,1 non-resonant component

  15. D0 KS+ - Dalitz Model hep-ex/0411049 • Belle: indentical approach • Include two more DCS resonances: K*+(1410) - , K*+(1680)- • 13 resonances (2 ), 5 DCS partners, 1 non-resonant component D*+ D0+, 186.9k events, purity 97% K*(892) DCS K*(892) m-2 (GeV2/c4) m+2 (GeV2/c4) 0(770) m-2 (GeV2/c4) 2 =2543/1106 =2.30 m2 (GeV2/c4) m+2 (GeV2/c4)

  16. Dalitz sensitivity scan to  CA: Cabibbo Allowed DCS: Doubly-Cabibbo Suppressed CS: Color Suppressed Sensitivity to (MC) =75°, =180°, rB =0.125 d2 ln L/d2 CA: D0K(892)*-+ CS: D0KS0(770) DCS: K0(1430)*+ - DCS: D0K(892)*+- D0 CA: K0(1430)*+ -

  17. GGSZ Method Results The two plots would be the same without CP violation. Are they?

  18. BaBar GGSZ Method Results hep-ex/0504039 D*0(D00)K D*0(D0)K DK m-2 B+ B+ B+ m-2 m+2 BABAR: 227M BB m+2 B– m-2 B– B– DCS K*(892) m-2 m+2 m+2

  19. Belle GGSZ Method Results hep-ex/0411049 DCS K*(892) - thick black line: with interference - thin grey line: without interference BELLE: 275M BB hep-ex/0504013

  20. BaBar GGSZ Method Results 68% 95% Frequentist CLs BABAR: 227M BB DK preliminary hep-ex/0504039 Frequentist CLs +0.036 DK : rB = 0.118 ± 0.079 ± 0.034 –0.034 B = ( 104 ± 45 )° +17 +16 –21 –24 +0.030 +0.029 D*K : rB*= 0.169 ± 0.096 –0.028 –0.026 D*K B*= ( 296 ± 41 ± 15 )° +14 –12  = ( 70 ± 31 ) ° +12 +14 –10 –11 stat. syst. Dalitz

  21. Belle GGSZ Method Results Promising results! rB hep-ex/0411049 DK BELLE: 275M BB B (deg) hep-ex/0504013 Frequentist CLs DK : DK rB = 0.21 ± 0.08 ± 0.03 ± 0.04 B = ( 157 ± 19 ± 11 ± 21 )° = ( 64 ± 19 ± 13 ± 11 )° rB[D*] D*K D*K : B[D*] (deg) rB*= 0.12 +0.16± 0.02 ± 0.04 -0.11 D*K B*= ( 321 ± 57 ± 11 ± 21 )° = ( 75 ± 57 ± 11 ± 11 )° DK* : (*) rB(K*)= 0.25 +0.17±0.09 ±0.04 ±0.08 rB[K*] DK* -0.18 B(K*)= ( 353 ±35 ±8 ±21 ±49 )° B[K*] (deg) (*) = ( 112 ±35 ±9 ±11 ±8)° (*) DK* Combined result of DK and D*K:  = ( 68 +14 13 11 ) ° -15 syst. Dalitz stat.  (degrees)  (degrees) (*) Possible bias caused by a contribution from non-resonant B–→ DKS–.

  22. rB(*) World Average 0 < D < 2rd ± 1 48° <  < 73° same, any  [ no improved constraint when adding  from CKM fit ] • BaBar ADS limit pushing rB down. • Belle Dalitz value (0.21) relatively large. RADS Frequentist CLs Belle ADS (90% CL) BaBar ADS (90% CL) Belle Dalitz BaBar Dalitz Using GLW, ADS, GGSZ results Bayesian CLs rB [BDK] 68% 95% 0.10  0.04 0.09  0.04

  23. CP violation in B0 D(*) / • CP violation through B0-B0 mixing and interference of amplitudes:  CP violation proportional to ratio rof amplitudes • Small: r  |V*ubVcd /VcbV*ud| 0.020  Large BF’s, at level of 1%  No penguin pollution  theoretically clean • Relative weak phase from bu transition • Relative strong phase  Suppressed amplitude through b  u transition Favored amplitude u,c,t u,c,t Strong phase difference CKM Unitarity Triangle g 

  24. sin(2+) from B0 D(*) / • Time evolution for B0 decays and B0 decays (Rmix) to D(*)/: • CP asymmetry: small sine terms  Need S+ and S- together to give (2+) and • From D(*)/ sine coefficients, 4 ambiguities in (2+) • Express result as |sin(2+)| • SM: sin(2+) ~ 1 Factorization theory:  is small SMALL sine terms

  25. sin(2+) Caveat: determination of r(*) • Simultaneous determination of sin(2+) and r(*)from time-evolution not possible with current statistics need r(*) as external inputs ! • Estimate r(*) from B0  Ds(*)+-/- using SU(3) symmetry[1] • Using:  [1] I. Dunietz, Phys. Lett. B 427, 179 (1998) SU(3) [2] Inputs used in CKMFitter/ UTFit : r(D) = 0.019 ± 0.004 r(D*) = 0.015 ± 0.006 r(D) = 0.003 ± 0.006 We add 30% theoretical errors to account for: • Unknown SU(3) breaking uncertainty • Missing W-exchange diagrams in calculation • Missing rescattering diagrams (Can be estimated with B0Ds(*)+K-) no theoretical errors included [2] fD : decay constants

  26. BaBar: Inclusive B0 D*  fast BABAR: 227M BB Using a,b,c parametrization: D* partial reconstruction: PRD68, 034010 Tag side interference: r’, ’ are the ratio and phase difference between the bu and bc amplitudes in the Btag decay. r’0 in lepton tags. lepton tags - High statistics! - Large backgrounds preliminary preliminary hep-ex/0504035 lepton tags peaking D* kaon tags combinatoric BB other peaking BB continuum 18710 ± 270 lepton tags70580 ± 660 kaon tags

  27. Belle: Inclusive B0 D*  hep-ex/0408106 preliminary BELLE: 152M BB • Belle: only uses lepton tags (no tag-side interference) sum signal bkg. Same Flavor: mixed events Opposite Flavor: unmixed events 8322 signal lepton tags

  28. BaBar: Exclusive B0 D(*)/ BABAR: 110M BB Phys.Rev.Lett. 92:251801(2004), 88 M BB • Exclusive reconstruction of channels: - B  D  - B  D*  - B  D     - Full reco.: ~10x less efficient; far lower backgrounds - Same sensitivity to sin(2+) as inclusive approach lepton tags hep-ex/0408059 preliminary

  29. Belle: Exclusive B0 D(*)  PRL 93 (2004) 031802; Erratum-ibid. 93 (2004) 059901 BELLE: 152M BB • Exclusive reconstruction of channels: - B  D  - B  D*  • Uses B  D*l as control sample for tag-side interference   cleanest tags (*) After tagging and vertexing

  30. HFAG on |sin(2+)| No clear CP violation yet! HFAG Averages:

  31. Combined Limit on |sin(2+)| Bayesian CLs www.utfit.org 68% 95% Combined limit on |sin(2+)| : Assuming 30% error on r(*) for SU(3) breaking: CKMFitter: |sin(2+)| > 0.53@ 68% C.L. UTFit: |sin(2+)| > 0.74@ 68% C.L. Frequentist CLs

  32. Outlook Many approaches to measure  have been investigated by BaBar and Belle. GLW and ADS methods don't provide strong constraints on  when considered alone. Current experimental results favour small values of rB.GGSZ results are promising! GLW+ADS+GGSZ: CKMFitter:  = [ 63 +15 ]°+ n UTFit:  = [ 64  18 ]°+ n sin(2+) from D(*)/: CKMFitter: |sin(2+)| > 0.53 @ 68% C.L. UTFit: |sin(2+)| > 0.74 @ 68% C.L. GLW+ADS+GGSZ+sin(2+): CKMFitter:  = [ 70 +12 ]°+ n All results are in good agreement with the global CKM fit ( = [ 60  6 ]°) All decay modes can use lots more statistics! High statistics expected in next years may allow BaBar and Belle to measure  to < 10°. -13  (deg) Using GLW, ADS, GGSZ results  = 64 ± 18 ([30,100] @ 95% CL) -14

  33. B A C K U P slides ...

  34. BaBar: Removing the Imaginary (?) 

  35. Belle GGSZ: Systematic Errors

  36. B  D*-+ time-dependent evolution B0 Flavor eigenstate With bu transition Flavor eigenstate B0(t) B0(t) D*-+ D*-+ Initialstate Initialstate B0 a) a) b) b) B  D*-+ B  D*-+ - pure cosine: r = 0 B0 • pure cosine: r = 0 - plus sine term, 5x the expected size in data r = 0.1,  = 0 sin(2+) = 1 B0 a) unmixed b) mixed No bu transition • CP asymmetry: small additional sine term • Smallness of amplitude ratio r greatly reduces sensitivity to sin(2+)

  37. () Dependency on rB • BaBar and Belle show quite different sensitivities to  • Both find quite different values for rB (BaBar: ~0.12, Belle: ~0.21) • Different sensitivity to  caused by dependency on rB . Toy MC Studies Comparing only results of BDK stat. Sensitivity to  very dependent on critical parameter rB (~0.1)! BaBar Belle rB [DK]

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