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Measurements of f 1 / b

Measurements of f 1 / b. K. Sumisawa (KEK). Flavor Physics and CP Violation 2010, May 25, 2010, Torino, Italy,. _. _. _. p q. q p. -i2 f 1. +i2 f 1. _. ~e. ~e. d. b. t. B 0. B 0. =. w. w. t. b. d. i f 1. V* td =| V td |e. Time-dependent CP Violation in B 0 decays.

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Measurements of f 1 / b

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  1. Measurements of f1/b K. Sumisawa (KEK) Flavor Physics and CP Violation 2010, May 25, 2010, Torino, Italy,

  2. _ _ _ p q q p -i2f1 +i2f1 _ ~e ~e d b t B0 B0 = w w t b d if1 V*td =| Vtd|e Time-dependent CP Violation in B0 decays KM ansatz: CPV is due to a complex phase in the quark mixing matrix _ B-B mixing V*td Unitarity Triangle mixing induced CP violation - b=f1 a=f2 g =f3 A A B0 fCP fCP B0 - A A B0 B0

  3. Time-dependent CP Violation in B0 decays We can measure CPV (asym.) as a function of proper time diff (Dt). A B0 fCP B0 A Dt Decay time difference between B meson pairs e.g. for B0J/ Ks S = -CPsin2f1 = +sin2f1 A ~ 0 (CP : CP eigenvalue 1) (A= -C) Mixing-induced CPV Direct CPV

  4. D z D t ≈ bg c ( ) ¡ Principle of Measurementin B-factories BCP e- e+ fCP(bc) (4S) DzcbgtB ~ 200 mm(Belle) ~ 250 mm(BABAR) bg ~ 0.43(Belle) ~0.56(BABAR) Btag Dz Flavor tag • Reconstruct B fCP(bc) decays • Measure proper-time difference: Dt • Determine flavor of Btag • Evaluate CP asymmetry from Dt and flavor of Btag

  5. 2 B-factories PEP-II 9GeV(e-),3.1GeV(e+) 1.21034cm-1s-1 4 lyr. BABAR Detector 83.5GeV 2.1×1034cm-2s-1

  6. Success of the B-factories Stopped in April 2008

  7. sin2f1 with charmonium K0 modes _ _ 465MBB 535MBB Nsig=7482 Purity=97% Nsig=8733 Purity=93% Nsig=6512 Purity=59% Nsig=5813 Purity=56% EB - ECM/2

  8. sin2f1 with charmonium K0 modes (cc)KS J/KL sin21=0.687±0.028±0.012 Af=-0.024±0.020±0.016 PRD79,072009(2009) sin21=0.642±0.031±0.017 Af=0.018±0.021±0.014 PRL98,031802(2007)

  9. sin2f1f1 error in f1 < 1 but ambiguities exist. agreement between two experiments

  10. _ B0  D[KSp+p-]h0 (h0=p0,w,h) Time dependent Dalitz analysis gives sin2f1 and cos2f1 describe Dalitz variables. cos2f1 >0 at 86% C.L cos2f1 >0 at 98.3% C.L. smaller f1 (<45) solutionis favored. _ consistent with bccs sin2f1

  11. constraint for f1/b • other measurement using • J/yK*0 (K*0Ksp0) • D*+D*-Ks • can also contribute.

  12. bccd tree + (penguin) J/y p0 : constrain penguin contribution in Golden mode(J/yK0)without model dependence. D(*)+ D(*)- : penguin contribution is expected to be small.

  13. bccd Belle A=-C=0.910.23  0.06 (3.2s significance A≠0) J/y p0 : constrain penguin contribution in Golden mode(J/yK0)without model dependence. D(*)+ D(*)- : penguin contribution is expected to be small.

  14. _ _ b b c J/Y c B0 w d d _ s _ w K0 d s f, h’... t g B0 s _ s K0 d bsqq TCPV Time-Dependent CP asymmetry in B0 decays _ S=sin21 A ~ 0 S=sin21eff A ~ 0 Extra CPV phase from New Physics Many two-body and quasi-two body analyses have been done. Since → K+K-, f0→ K+K- and non-resonant contributions overlap invariant mass(as do 0→ +- and f0→ +-), recently time-dependent Dalitz analyses have been performed in three-body decays such as B0→ (K+K-)KS and B0→ (+-)KS.

  15. f(1020)KSCP= -1 f(1020) KS A1 f0(980)KS A2 f0(980)KSCP= 1 B0 K+K-KS Non-resonant Non-resonant CP=+0.86±0.20 AN Interferences in B decays with K＋K-Ksfinal state • Dalitz-plot ⇒ distinguish the intermediate states considering interferences • Opposite CP eigenvalue from fKs ⇒State-by-state CP measurement Dalitz-plot

  16. Time-dependence of Dalitz plot in B0→K＋K- Ks A B0 K+K-KS f (1020)KS B0 A B0 f0(980)KS c.f. Time-dependence K+K-KS A A B0 Time-dependence Dalitz-plot Interference in B0 B0 (f1,eff)+ intermediate states (Dalitz phase) CP asymmetry (f1,eff, ACP) of Bf(1020) KSusing Time-dependent Dalitz plot analysis in BK+K-Ks

  17. updated Belle result (B0K+K-Ks ) Decay amplitude Belle 657MBB to be submitted to PRD. RBW: Relativistic Breit Wigner • 19 free parameters • 12: isobar model • 6: CPV parameters. • 1: a for NR

  18. Multiple solution 4 preferable solutions Decay mode fractions • External information from B0→ p +p - Ks • f0(980) • B.F.(f0(980)→p +p -)/B.F.(f0(980)→K+K-) and compare with PDG • solutions with low f0(980)Ks fraction preferred • fx(1500) • If fx(1500)=f0(1500) for both decays • B.F.(f0(1500)→p +p -)/B.F.(f0(1500)→ K+K-) and compare with PDG • solutions with low fx(1500)Ks fraction preferred Solution 1 preferred.

  19. fit result (Dalitz plot) Solution 1 f(1020) fx(1500) cc0 D veto J/y veto background

  20. fit result (Dt plot) Solution 1 Belle 657MBB to be submitted to PRD. proper time distribution and raw asymmetry plot in f mass region SM expectation background the third error: Dalitz plot model uncertainty

  21. BABAR K+K-Ks result BABAR 465MBB arXiv:0808.0700 (7.77.7 0.9) (8.57.5 1.8) whole region low mass region

  22. average in BfKs, Bf0(980)Ks (7.77.7 0.9) (8.57.5 1.8) Consistent with the Standard Model prediction at current sensitivity f1(bccs)= (21.0 ± 0.9)°

  23. result using p+p-Ks Belle 657MBB PRD79(2009) 072004 BABAR 383MBB PRD80(2009) 112001

  24. Compilation of effective sin21 Still precision is statistically dominated. ↓ To obtain sensitivity in effective sin21of O(10-2), we need O(10ab-1) of integrated luminosity.

  25. Summary • f1/b = (21.1 0.9) in B-factories • sin2f1 from bccs modes. • resolve the quadratic ambiguity by measuring cos2f1 with Dalitz analysis, etc. • penguin modes are good probes of new physics. We need more data. • Belle is now updating its result with the full data sample. • J/yK0 • full data: 535M771MBB (factor 1.44) • improved tracking software: 20% gain for J/yKs • yield : factor 1.61 • y(2S)Ks, cc1Ks, hcKs, and combined analysis last update with150MBB (657MBB for y(2S)Ks) • (statistical error for sin2f1)~0.02 • etc.. _ _ _

  26. backup

  27. background Combined result:

  28. Resonances considered in the KsKK signal model

  29. Signal PDF Time-dependence Dalitz-plot × ⇒19 fit parameters q = 2 q Decay amplitude • 1. Dalitz amplitude and phases • 2. CP-violating amplitude and phases (fKs, f0Ks, others) • 3. Kinematics (Dalitz plot)a for NR B0: B0:

  30. Reconstructed B0→KsK+K- candidates • Event selection • B0→KsK+K- reconstruction • Ks selection • K± selection by PID (K/p) • Continuum suppression • Efficiency: ~16% • Unbinned ML fit to DE and Mbc distributions • B0→KsK+K- 1176±51evts. Purity~50% • Background • Continuum ~47% • Other B decays ~3% DE Signal Continuum Other B decays Mbc Event-by-event signal probability fsig(DE, Mbc) for CP measurement Time-dependent Dalitz plot fit to the selected B0KsK+K- candidates.

  31. plots for K+K-Ks Belle 657MBB ICHEP2008 preliminary f mass region signal background raw asymmetry plot in f mass region ACP (Dt)

  32. BABAR K+K-Ks result BABAR 465MBB arXiv:0808.0700 (7.77.7 0.9) (8.?8.?) (8.57.5 1.8) (19711) whole region low mass region

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