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Measurements of a and future projections

Measurements of a and future projections. Fabrizio Bianchi University of Torino and INFN-Torino Beauty 2006 The XI International Conference on B-Physics at Hadron Machines. Outline. Introduction to the measurement of a Results from the B-factories:

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Measurements of a and future projections

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  1. Measurements of aand future projections Fabrizio Bianchi University of Torino and INFN-Torino Beauty 2006 The XI International Conference on B-Physics at Hadron Machines

  2. Outline • Introduction to the measurement of a • Results from the B-factories: • B p+ p-, p± p0, p0 p0 • B r+ r-, r± r0, r0 r0 • B0 (r p)0 • Summary and outlook • Will not cover expectations at LHC and Super B-Factories • See talks of P. Robbe and A. Bevan

  3. Measuring a Access to a from the interference of a b→u decay (g) with B0B0 mixing (b) Inc. penguin contribution

  4. From aeff to a: Isospin Analysis Gronau and London, Phys. Rev. Lett. 65, 3381 (1990) Assume SU(2) symmetry among amplitudes Neglecting EW Penguins: is a pure tree mode. The triangles share a common side.

  5. Time Dependent Analysis Outline • Fully reconstruct the B decaying to a CP eigenstate. • Tag the flavor of the other B. • Mis-tag probability measured in Bflav sample. • Measure Dt. • Extract S and C with a ML fit on a signal enriched sample. • Signal PDF from MC. • Background PDF from MC or sidebands

  6. Variables used in the ML fit Event Topology Combine variables in For N signal signal • PID info: • DIRC + dE/dX (BaBar) • Aerogel + dE/dX (Belle) • Dt background background

  7. 347 million BB hep-ex/0607106 :results (preliminary) Background Signal B0tag mES B0tag mES DE DE Npp = 675±42 sPlot

  8. 535 million BB hep-ex/0608035 :results (preliminary) Npp = 1464±65

  9. C =−A :results (preliminary) 347 million BB Cpp = - 0.16 ± 0.11 ± 0.03 Spp = - 0.53 ± 0.14 ± 0.02 BaBar (Spp, Cpp) = (0.0, 0.0) excluded at 3.6 s Average 535 million BB Belle Cpp = - 0.55 ± 0.08 ± 0.05 Spp= - 0.61 ± 0.10 ± 0.04 2.3 s discrepancy Observation of Direct CPV at 5.5 s Observation of mixing-induced CPV at 5.6 s

  10. (preliminary) 347 million BB hep-ex/0607106 Np±p0 = 572 ± 53 Np0p0 = 140 ± 25

  11. Da = a - aeff a constraint from Da 1- C.L. |Da| < 41o at 90% C.L. a a Frequentist interpretation: use only the B→pp branching fractions and isospin-triangle relations. 1- C.L. No stringent constraint from ppsystem alone  needrrandrp

  12. Theanalysis • Worse than pp at first sight: • V V final state. Mixture of CP = +1 and -1: need to know each fraction • However: • ~100% longitudinally polarized (~pure CP-even state) • no need for elaborate angular analysis • Branching fraction for B0gr+r- is larger than p+p- • Branching fraction for B0gr0r0 is small (~1.1x10-6) • small penguin pollution

  13. results (preliminary) 347 million BB hep-ex/0607098

  14. results 275 million BB PRL 96, 171801 (2006) Nrr = 194±32

  15. results (preliminary)

  16. results (preliminary) 232 million BB hep-ex/0607092 Nr+r0 =390 ± 49

  17. results (preliminary) 347 million BB hep-ex/0607097 Nr0r0 = 98 ± 32± 22 3.0 s evidence

  18. a constraint from hep-ex/0607098 PRL 96, 171801 (2006) [71, 105]o at 68.3% C.L. Use BR(B->r0r0)<1.1 X 10-6 a Frequentist interpretation: use only the B→ρρ branching fractions, polarization fractions and isospin-triangle relations. First evidence of B→r0r0 Constraint on a is less stringent

  19. TheDalitzanalysis A. Snyder and H. Quinn, Phys. Rev. D, 48, 2139 (1993) r+p- r-p+ r0p0 B0 p+p-p0 B0 Monte Carlo • Time-dependent Dalitz-plot analysis assuming isospin simmetry. • 26 coefficients of the bilinear form factor terms occurring in the decay rate are measured with a UML fit. • Physically relevant quantities are derived from subsequent fits to these coefficients. Interference provides information on strong phase difference r(1450) and r(1700) are included

  20. analysis (preliminary) 347 million BB hep-ex/0608002 m’ and q’ are the transformed Dalitz variables

  21. analysis (preliminary) 449 million BB hep-ex/0609003 • Dalitz + Isospin (pentagon) analysis • 26(Dalitz) + 5(Br(rp), Br(r+p0), Br(r0p+), A(r+p0), and A(r0p+)) r+p- r-p+ r0p0 Signal SCF BB bkg continuum mass helicity

  22. a constraint from (preliminary) [0,8]o U [60,95]o U[129,180]o at 68.3% C.L. 1- C.L. 1- C.L. a (deg) a (deg)

  23. Belle rp result is not included. It will weakens the suppression of solutions around 0o and 180o. +11 -9 aB-Factories = [ 93 ] º +5 -19 aGlobal Fit = [ 98 ] º CKMfitter http://ckmfitter.in2p3.fr/ UTfit http://utfit.dreamhosters.com/ aconstraints Global Fit B-Factories aB-Factories = [92 ± 7]o (SM Solution) aGlobal Fit = [93 ± 6]o Nice agreement

  24. Pending Issues • Discrepancy on Cpp • Solutions at 0o and 180o should be (more) suppressed. • Using rp: nice suppression from BaBar, not from Belle. • Background modeling. • Interference with other resonances or non-resonant component in rp, rr modes. • Subtleties on statistical analysis with small statistics. Cpp = - 0.16 ± 0.11 ± 0.03 Cpp = - 0.55 ± 0.08 ± 0.05

  25. Uncertainties on a extraction • Possible contribution of EW penguin and isospin breaking effect. • EW penguin effect seems to be small (~2°). • Other isospin breaking effect ~ O(1°). [M.Gronau and J.Zupan PRD 71, 074017(2005)] • I=1 contribution due to finite width of r mass (rr mode). [A.Falk et al. PRD 69, 011502(R)] Too small to be an issue at B-factories

  26. Summary and Outlook • The three modes are complementary. • Need to study them all. • Good agreement between the CKM fit (a determined by others) and direct measurements. • Still a lot to do. • Refine previous analysis and exploit new ideas: • a from B->a1p ? • Constraint on a from B0->r+r- and B+->K*0r+ [M. Beneke et al., Phys. Lett. B638, 68(2006)] • Doubling of statistics at the B-factories is much needed. • Looking forward to LHC and to a Super B-Factory.

  27. Backup Slides

  28. CP Time Dependent CP Asymmetry mixing decay Amplitude ratio CP eigenvalue

  29. BABARDetector

  30. DIRC: Control samples for p and K p K Projection for 2.5 < p < 3 GeV/c

  31. :results (preliminary) Cpp = - 0.16 ± 0.11 ± 0.03 Spp = - 0.53 ± 0.14 ± 0.02 (Spp, Cpp) = (0.0, 0.0) excluded at 3.6 s

  32. :results (preliminary) App = + 0.55 ± 0.08 ± 0.05 Spp= - 0.61 ± 0.10 ± 0.04 Observation of Direct CPV at 5.5 s Observation of mixing-induced CPV at 5.6 s

  33. a constraint from

  34. a constraint from

  35. formalism Direct CP Violation CP violation in the interference with and without B mixing.

  36. parameters (prelim)

  37. Direct CP violation in Significance for non-zero DCPV: BaBar:3.0 s Belle:2.4 s

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