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f 3 measurements by Belle

f 3 measurements by Belle. Pavel Krokovny KEK. Introduction Apparatus Method Results Summary. Unitarity Triangle. Using unitarity requirement :. φ 1 is measured with a high accuracy (~1º) at B-factories . φ 3 is the most challenging angle to measure.

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f 3 measurements by Belle

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  1. f3 measurements by Belle Pavel Krokovny KEK Introduction Apparatus Method Results Summary

  2. Unitarity Triangle Using unitarity requirement: φ1 is measured with a highaccuracy (~1º) atB-factories. φ3 is the most challenging angle to measure. Measurement of all the angles needed to testSM.

  3. Constraints of the Unitarity Triangle World average as of summer 2005 from GLW, ADS, Dalitz and sin(2φ1+φ3): γ/φ3=70 -14° +12

  4. KEKB and Belle KEKB Collider 3.5 GeV e+ & 8 GeV e–beams 3 km circumference, 11 mrad crossing angle L= 1.65 x 1034 cm–2s–1 (world record) L dt = 630 fb–1 @ Υ(4S)+off(~10%)

  5. B+ D0K+ decay Need to use the decay whereVubcontribution interferes with another weak vertex. B– D0K–:B– D0K–: If D0 and D0decay into the same final state, Relative phase: (B– DK–), (B+ DK+) includesweak (γ/φ3) and strong (δ) phase. Amplitude ratio:

  6. GLW method M. Gronau and D. London, PLB 253, 483 (1991); M. Gronau and D. Wyler, PLB 265, 172 (1991) СР eigenstateofD-meson is used (DCP). CP-even : D1K+K–, π+ π– CP-odd : D2 KS π0, KS ω, KS φ, KSη… СР-asymmetry: forD1  A1,2of different signs forD2 Additional constraint: 4 equations (3 independent: ), 3 unknowns

  7. GLW method Belle results (253 fb-1) Phys. Rev. D 73, 051106(R) (2006) B± DK± B+ D1K+ B- D1K- B± D*K± B+ D2K+ B- D2K- GLW analyses alone do not constrain γ/φ3 significantly yet, but can be combined with other measurements and provide information on rB

  8. ADS method D. Atwood, I. Dunietz and A. Soni, PRL 78, 3357 (1997); PRD 63, 036005 (2001) Enhancement of СР-violationdue to use ofCabibbo-suppressedD decays B–D0K–- color allowed D0K+π– - doublyCabibbo-suppressed B–D0K–- color suppressed D0K+π– - Cabibbo-allowed Interfering amplitudes are comparable 

  9. ADS method Belle results (357 fb-1) hep-ex/0508048 Suppressed channel not visible yet: UsingrD=0.060±0.003, for maximum mixing (φ3=0, δ=180°): rB<0.18 (90% CL)

  10. Dalitz analysis method A. Giri, Yu. Grossman, A. Soffer, J. Zupan, PRD 68, 054018 (2003) A. Bondar, Proc. of Belle Dalitz analysis meeting, 24-26 Sep 2002. Using 3-bodyfinalstate, identical for D0and D0: Ksπ+π-. Dalitz distribution density: (assuming СР-conservationin D0 decays) If is known, parameters are obtained from the fit to Dalitz distributionsof DKsπ+π–fromB±DK±decays

  11. Dalitz analysis: D0 Ksπ+π– Statistical sensitivity of the method depends on the properties of the 3-body decay involved. (For|M|2=Const there is no sensitivity to the phaseθ) Large variations ofD0decay strong phase are essential Use the model-dependent fit to experimental data from flavor-tagged D* D0π sample. Model is described by the set of two-body amplitudes + nonresonant term. As a result, model uncertainty in the γ/φ3 measurement.

  12. M (GeV 2 ) Ksπ – 2 D0 Ksπ+π– Decay Model D*->D0π->[KSπ+π-]π Doubly Cabibbo Suppressed K* ρ-ω interference

  13. Dalitz analysis: sensitivity to f3

  14. Dalitz analysis Phys. Rev. D 73, 112009 (2006) Fit parameters are x= r cos(φ3+δ) and y= r sin(φ3+δ) (better behaved statistically than ) are obtained from frequentist statistical treatment based on PDFs from toy MC simulation. BDK BD*K BDK* x–= 0.025-0.080 y–= 0.170-0.117 x+= –0.135-0.070 y+= –0.085-0.086 x-= –0.128-0.146 y-= –0.339-0.158 x+= 0.032-0.116 y+= 0.008-0.136 x–= –0.784-0.295 y–= –0.281-0.335 x+= –0.105-0.167 y+= –0.004-0.156 +0.072 +0.167 +0.249 +0.093 +0.172 +0.440 +0.069 +0.120 +0.177 +0.090 +0.137 +0.164

  15. Dalitz analysis Phys. Rev. D 73, 112009 (2006) Belle result (357 fb-1) BD*K BDK* BDK 81±8 events 54±8 events 331±17 events B- B+ B- B- B+ B+

  16. Dalitz analysis Phys. Rev. D 73, 112009 (2006) BDK BDK* BD*K φ3=86-93°(stat) φ3=11-57°(stat) φ3=66-20 °(stat) +23 +19 +37 Combined for 3 modes:φ3=53°+15 3° (syst)9° (model) 8°<φ3<111° (2σ interval) rDK =0.159+0.054 0.012(syst)0.049(model) CPV significance: 74% rD*K=0.175+0.108 0.013(syst)0.049(model) rDK*=0.564+0.216 0.041(syst)0.084(model) -18 -0.050 -0.099 -0.155

  17. sin(2φ1+φ3) fromB0 D*πdecay Decay : + Use B flavor tag, measure time-dependent decay rates: Btag B0 B  D-+ Btag B0 CP violation where

  18. sin(2φ1+φ3) Phys. Rev. D 73, 092003 (2006) Belle result (357 fb-1) - full reconstruction with - partial reconstruction (reconstruct only pions) D*π partial rec D*π full rec

  19. sin(2φ1+φ3) Phys. Rev. D 73, 092003 (2006) S +(D*π)=0.049±0.020±0.011 S –(D*π)=0.031±0.019±0.011 S +(Dπ)=0.031±0.030±0.012 S –(Dπ)=0.068±0.029±0.012 Full-rec + partial-rec Full-rec CP violation significance: 2.5σ If R~0.02: |sin(2φ1+φ3)|>0.46 (0.13) |sin(2φ1+φ3)|>0.48 (0.07) at 68% (95%) CL

  20. Summary • The angle φ3/g remains the most difficult angle of the Unitarity • Triangle to measure, although there is a tremendous progress • from B-factories. • O(20º) Precision in direct measurements of φ3 is achieved using new • GGSZ method (B->D0[KSππ]K) • Other methods do not constrain γ/φ3significantly yet, but can be used in combined fit and provide information on rB • The precision is statistically limited  good perspectives for • improving the result with larger data set

  21. Backup

  22. B± DK±, DKSπ+π– Dalitz plots K*(892) bands D0fromB- D0K- (π+andπ -interchanged) D0 fromB+ D0K+

  23. Control sample Same fit procedure was applied for the control sample: B  D(*)p The results are consistent with r=0.01 for D(*)0 and with 0 for D*- p+

  24. Systematic errors Background shape: baseline – BB MC + continuum data sample, variations – continuum only, MBC sidebands. Efficiency over Dalitz plot: main fit – MC, variation – use high momentum D*[D p] DE – MBC shape: vary shape parameters by 1 s DE – MBC for BB and qq: use different shape for qq and BB

  25. D0 Ksπ+π– decay model

  26. Model-independent approach D0 decay amplitude: D0-D0 interference from B+ D0K+: is measured directly, is model-dependent If CP-tagged D0 are available (e.g. from ψ’’ D0D0, where tag-side D0decays into CP-eigenstate) phase difference can be measured:

  27. Model-independent Approach A.Bondar, A.Poluektov hep-ph/0510246 A.Giri, Yu. Grossman, A. Soffer, J. Zupan, PRD 68, 054018 (2003) 50 ab-1 at SuperB factory should be enough for model-independent γ/φ3 Measurement with accuracy below 2° ~10 fb-1 at ψ(3770) needed to accompany this measurement.

  28. Dalitz analysis: sensitivity to f3

  29. Constraints to rB

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