1 / 32

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.

jblume
Télécharger la présentation

Measurements of f 1 / b

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related