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Phase of B Factories: f2 Angle Constraint from Decays A, KM Model Validation in CP Violation

This workshop presentation delves into the vital role of the f2 parameter in validating the Kobayashi-Maskawa (KM) model and ensuring Unitarity Triangle closure. Topics covered include CP violation measurements, rare decays, and the search for physics beyond the Standard Model. Insight into the f2 angle's significance, detailed decay diagrams, and discussions on CP violation confirmations enrich the exploration of mass origin and supersymmetry in particle physics research.

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Phase of B Factories: f2 Angle Constraint from Decays A, KM Model Validation in CP Violation

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  1. Constraint on CKM angle f2 from B decays A. Kusaka (University of Tokyo), on behalf of Belle collaboration Fourth Workshop on Mass Origin and Supersymmetry Physics Mar. 6-8, 2006, Tsukuba, Japan

  2. New “phase” of B factories • Confirmation of KM model of CPV • sin2f1 by J/yK0, etc… • f2 • f3 • Vub, etc… • Search for the physics beyond SM = New “phase” from new physics • Rare decays • Consistency check (Unitarity Triangle closure)

  3. So, why f2 ? Fundamental parameter of KM model Essential to check the Unitarity Triangle closure

  4. Contents • Principle • CP violation measurement • CPV measurement of B0p+p– • CPV measurement of B0r+r– • Isospin analysis • Penguin pollution • Isospin analysis • Dalitz-Dt analysis with Brp

  5. – – – – – – t u d b b u d p/r – B0 B0 t b d p/r B0 d d Mixing diagram Decay diagram (tree) CKM triangle and f2 f2 VtdV*tb VudV*ub f3 f1 VcdV*cb Vtb V*td V*ud Vub Vtd V*tb

  6. – – – V*ud u d b u p/r Vub p/r B0 d d CKM triangle and f2 B0  p+p- B0  r+r- B0  rp

  7. CP violation measurement

  8. q B e– e+ e– e+ q B B0p+p-: Event selection • Event reconstruction • PID (K/p separation) • Continuum suppression (modified SFW, flavor tagging information)

  9. High Quality region Number of events MBC (GeV) DE (GeV) good tag 66643 events used CPV measurement of B0p+p– Spp = 0.67 0.160.06 App = +0.56 0.120.06 4s evidence of Direct CPV! Published as PRL 95, 101801

  10. B0p+p-: Belle vs. BaBar App B0 tagged Belle 275MBB – B0 tagged Spp BaBar 227MBB 2.3s discrepancy between Belle and BaBar Spp = 0.30 0.170.03 App = +0.09 0.150.04 PRL 95, 151803

  11. CPV measurement of B0r+r– Differences from B0p+p– • Good point • Small branching fraction of B0r0r0 (<1/20) compared with B0r+r-and B+r+r0. small penguin pollution • Bad (difficult) points • Decay product contains two p0 lower efficiency, larger BG • Consists of three polarization states polarization measurement is essential

  12. Number of events Mpp (GeV) Good tag Number of events MBC (GeV) DE (GeV) B0r+r-: Event selection • The same technique as B0p+p- • DE, Mbc • PID • SFW + tagging info. • The information of r mass is also used. • 0.62<Mpp<0.92 (GeV/c2)

  13. Fortunately, longitudinal polarization is dominant. # of Events Belle preliminary cosq Polarization • B0r+r– has 3 polarization states with different CP eigenvalues Transverse Longitudinal

  14. Belle preliminary 2f2eff ~ 180 (deg.) Time dependent fit q=-1 q=+1 No CP violation good tag poor tag 19432 events used hep-ex/0601024

  15. B0r+r-: Belle vs. BaBar App Belle 275MBB Spp BaBar 232MBB Consistent with each other PRL 95, 041805

  16. Isospin analysis

  17. V*ud p/r Vub p/r Vtb V*td u B0 d – f2 B0 B0 Tree diagram t b d – – – – – – Vtd V*tb d t b u d b d Penguin pollution + Mixing diagram

  18. V*ud p/r Vub p/r Vtb V*td u B0 d – f2 B0 B0 Tree diagram t b d – – – – – – – – – – Vtd V*tb d t Vtb d u b d b b u t d V*td p/r u 0 B0 p/r d d Penguin diagram Penguin pollution + Mixing diagram +

  19. Isospin analysis (how to get k) • BF and asymmetries: World average (HFAG) • Ahh and Shh: Belle measurement above.

  20. Due to the large App, one of the triangles are squeezed. Situation of Bpp Belle at 1s excluded at 90% C.L.

  21. Belle at 1s excluded at 90% C.L. Situation of Bpp BaBar excluded at 90% C.L.

  22. Due to the small Br of B0r0r0, both of two triangles are squeezed. Good determination of f2 (with only two mirror solutions) Situation of Brr Belle at 1s at 90% C.L.

  23. BaBar Belle at 1s at 1s at 90% C.L. at 90% C.L. Situation of Brr

  24. Dalitz-Dt analysis with B0rp

  25. Dalitz-Dt analysis with B0rp Snyder & Quinn, 1993 • Dalitz Plot  Final states can be resolved r+p-, r-p+, r0p0, +interferences. • Measure their time dependence. • Sufficient information to determine all the amplitudes, including strong phase d. s-=m2(p-p0) s+=m2(p+p0) BaBar preliminary hep-ex/0408099 f2

  26. Combined results

  27. Belle at 1s at 90% C.L. Combined results

  28. Belle BaBar at 1s at 1s at 90% C.L. Combined results

  29. f2 W.A. Belle at 1s CKM (indirect) at 90% C.L. All W.A. Combined results

  30. Summary and prospects • CKM angle f2 is measured with Bpp, rr, and rp. • Combining Bp+p- and Br+r- from Belle, we constrain f2=93+12-11 for 1s. • The value from direct measurements is consistent with that from indirect measurements. • With increased data set and modes, we will soon obtain the result with much better precision.

  31. SU(3) expectation on App and AKp • Expectation by theory • App ~ -AKp/3 N. G. Deshpande, and X.-G. He, Phys. Rev. Lett. 75, 1703-1706 (1995), hep-ph/9412393. Gronau, and J. L. Rosner, Phys. Lett. B595, 339-346 (2004), hep-ph/0405173. • Measurements by experiment • App = +0.56 0.120.06 (Belle) • App = +0.09 0.150.04(BaBar) • AKp = -0.113 0.0220.008 (Belle) • AKp = -0.133 0.0300.009 (BaBar)

  32. B.F. used for Isospin analysis • Br(r+r0) fL(r+r0) = 25.6 +- 6.5 • Br(r+r-) fL(r+r0) = 24.4 +- 3.7 • Br(r0r0) = 0.54+0.407-0.372 • Asym(r0r0) = N/A • Br(p+p0) = 5.5 +- 0.6 • Br(p+p-) = 4.6 +- 0.4 • Br(p0p0) = 1.51 +- 0.28 • Asym(p0p0) = 0.28 +- 039

  33. chi2 of isospin analysis • chi2 of isospin analysis. • pp: 0.35 • rr: 0.60 • combined: 1.15

  34. Comparison with BaBar Belle 275M BB BaBar 227M BB 232M BB Difference from Belle is 2.3s Results are consistent with each other.

  35. Data used 253/fb – 253/fb (275M BB) until 2004 summer is used.

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