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Constraint on CKM angle f 2 from B decays

Constraint on CKM angle f 2 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. New “phase” of B factories. Confirmation of KM model of CPV sin2 f 1 by J/ y K 0 , etc…

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Constraint on CKM angle f 2 from B decays

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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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