1 / 38

Physics from B Decays: Lifetimes, Mixing, CP-Violating Asymmetries and Rare Hadronic Decays

Physics from B Decays: Lifetimes, Mixing, CP-Violating Asymmetries and Rare Hadronic Decays. Patricia Burchat Stanford University. Some of the Highlights …. Outline. The B Factory Experiments B lifetimes and mixing Time-dependent CP-violating asymmetries CP charge asymmetries

sileas
Download Presentation

Physics from B Decays: Lifetimes, Mixing, CP-Violating Asymmetries and Rare Hadronic Decays

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. Physics from B Decays:Lifetimes, Mixing, CP-Violating Asymmetriesand Rare Hadronic Decays Patricia Burchat Stanford University Some of the Highlights …

  2. Outline • The B Factory Experiments • B lifetimes and mixing • Time-dependent CP-violating asymmetries • CP charge asymmetries • B hadronic decay rates Motivation for measurements. How well have we measured these properties? What have we learned? Patricia Burchat, Stanford

  3. BABAR/PEP-II peak luminosity: 4.6 x 1033cm-2s-1 (~5 BB/s) max lumi/24h: 303 pb-1 total recorded lumi to date: ~90 fb-1 recorded (~10% off-peak) 4.5-month shutdown starts July 1, 2002 Belle/KEK-B peak luminosity: 7.2 x 1033cm-2s-1 (~8 BB/s) max lumi/24h: 388 pb-1 total recorded lumi to date: ~80 fb-1 recorded (~10% off-peak) 2-month shutdown starts July 1, 2002 The B Factory Experiments • c.f. integrated luminosity for • Argus (1983-1987): ~100 pb-1 • CLEO (1981-2000): ~16 fb-1 Patricia Burchat, Stanford

  4. d s b u c t The Unitarity Triangles (K system) d•s* = 0 (Bs system) s•b* = 0 (Bd system) d•b* = 0 These three triangles (and the three triangles corresponding to the rows) all have the same area. A nonzero area is a measure of CP violation and is an invariant of the CKM matrix. apply unitarity constraint to pairs of columns Patricia Burchat, Stanford

  5. d s b u c t The Unitarity Triangle Vtb*Vtd Vub*Vud a b g Vcb*Vcd Orientation of triangle has no physical significance. Only relative angle between sides is significant. apply unitarity constraint to these two columns Patricia Burchat, Stanford

  6. d s b u c t The Unitarity Triangle (r,h) Vtb*Vtd Vcb*Vcd Vub*Vud Vcb*Vcd a b g (1,0) (0,0) apply unitarity constraint to these two columns Patricia Burchat, Stanford

  7. We are sensitive to CP-violating CKM phases through interference between two decays with known (or unknown) CP-conserving relative phases. Meson mixing provides a source of error-free non-CKM phase shift by 90o ( i): |B0 (t)  cos(Dm t/2) |B0 – i sin(Dm t/2) |B0 exp(2if), where the CKM angle f is associated with the mixing box diagram. Interference between two decay diagrams (e.g., tree and penguin amplitudes with different CKM phases) can lead to CP-violating asymmetries but interpretation depends on relative strong phase. Patricia Burchat, Stanford DK

  8. p+ p— B0 / B0 e - e + e ±, m ±, K± tag Dz B0 / B0 Dz ~ 255 mm for PEP-II: 9.0 GeV on 3.1 GeV ~ 200 mm for KEKB: 8.0 GeV on 3.5 GeV The Asymmetric-Energy B Factories (4S) Patricia Burchat, Stanford

  9. CP states sorted by B tag flavor B0 B0 or B0 B0 Btag= B0 Btag= B0 B0 B0 or B0 B0 CP violation dN exp(–|Dt|/tB) ( 1 ± sin2b sin(DmDt) ) Dt distributions with NO experimental effects Flavor states sorted by mixing status B Mixing dN exp(–|Dt|/tB) ( 1 ± cos(DmDt) ) Patricia Burchat, Stanford

  10. Unmixed – Mixed ~ (1 – 2w) Unmixed + Mixed ~ p / Dmd perfect flavor tagging and time resolution realistic mistag and finite time resolution Asymmetry  (1 – 2w) cos(DmdDt) Patricia Burchat, Stanford

  11. B0 Lifetime ( x 10-12 ps) 1.548  0.032 1.542  0.016 Ratio of B+ to B0 Lifetime 1.060  0.029 1.083  0.017 B0 Mixing Frequency ( x 1012 ps-1) 0.472  0.017 0.489  0.009 PDG2000 10 measurements 12 measurements 18 measurements PDG2002 +3 B Factory +2 LEP +2 B Factory +1 LEP +3 B Factory +1 LEP   Flavor Session V: U. Nierste (theory)   CKM/CP III and FP VIII Increase in precision of B lifetimes and mixing frequency Patricia Burchat, Stanford

  12. Prospects for future lifetime and mixing measurements • many preliminary lifetime and mixing results. • systematic uncertainties dominated by Dt resolution function and, for mixing, knowledge of the lifetime. • measure mixing and lifetime simultaneously • expect <1% uncertainty on Bd mixing in a few years. • measure DG. • test assumptions of CP/T/CPT symmetries.   Flavor Session VIII, T. Meyer Patricia Burchat, Stanford

  13. sin2b Vtb*Vtd b Vcb*Vcd Patricia Burchat, Stanford

  14. Belle has observed a 6s signal that is most likely the not-well-established c(2S) charmonium state in B0c(2S) Ks0 and B+ c(2S) K+   CKM/CP Session V, S. Olsen Charmonium modes used for measuring sin2b b c , c, c One dominant decay amplitude  theoretically clean! c B0 s KS,L d d Both BABAR and Belle use six charmonium modes: • B  J/ Ks0, Ks0p+p-, p0p0 • B  J/ KL0 • B (2S) Ks0 • B c1 Ks0 • B  J/ K*0, K*0  Ks0 • B c Ks0 Patricia Burchat, Stanford

  15. sin2b data samples in BABAR c1 Ks J/Y Ks (Ks p+p-) J/Y Ks (Ksp0p0) Bflav Mixing sample Y(2s) Ks J/Y K*0 (K*0  Ksp0) J/Y KL Patricia Burchat, Stanford

  16. hep-ex/0205020 Belle 42 fb-1 (44 M BB) 1772 events (78% purity) 1550 evts with Dt meas’t effective tagging efficiency: e=(27.0  1.2)% sin2b = 0.82  0.12  0.05 || = 1.06  0.09 (stat)   CKM/CP Session I, Wang, Vahnsen Patricia Burchat, Stanford

  17. hep-ex/0203007 BABAR 56 fb-1 (62 M BB) 1850 tagged events with Dt (79% purity; 68% tagging e) effective tagging efficiency: e=(25.1  0.8)% sin2b = 0.75  0.09  0.04 || = 0.92  0.06  0.02 471 events 524 events   CKM/CP Session I, Rahatlou, Lange Patricia Burchat, Stanford

  18. Constraints on upper vertex of Unitarity Triangle from all measurements EXCEPT sin2b b Regions of >5% CL A. Höcker, H. Lacker, S. Laplace, F. Le Diberder, Eur. Phys. Jour. C21 (2001) 225, [hep-ph/0104062] Patricia Burchat, Stanford

  19. World Average sin2b = 0.78  0.08 The Standard Model (and the CKM paradigm, in particular) wins again … at least at the current level of experimental precision, in this decay mode. Patricia Burchat, Stanford

  20. B0 B0 Measurement of “sin2b” in bccd decays: D*D*+ and D*D+ c b t d D(*)- D(*)- c d b c c D(*)+ D(*)+ d d d d • Weak phase for tree decay is same as for bccs but watch out for penguins! • D*D* is vector-vector decay (L=0,1,2) so mix of CP=+1 and –1. • Fit for Sfand Cf (no penguin assumptions). D*D* Ntag = 76 Purity = 80% D*D* S = - 0.05  0.45  0.05 C = 0.12  0.30  0.05 CP asymmetries in D* D+ have also been studied in BABAR.   CKM/CP Session I, J. Albert Patricia Burchat, Stanford

  21. s b t s  s  s b t s B0 B0 s K0 K0 d d d d Future sin2b studies:B0Ks • Pure penguin! • time-dependent asymmetries in B0Ks measures sin2b. • direct charge asymmetries in B+K+ sensitive to new physics. Patricia Burchat, Stanford

  22. ~60M BB pairs Branching Fractions (10-6) (stat. and syst. errors added in quadrature and symmetrized) CLEO, Belle, BABAR B K BABAR K+ 111±12 evts •  K+5.5±2.0, 11.2±2.4, 9.2±1.3 •  K0<12, 8.9±3.2, 8.7±1.8 •  K*+<23, <36, 9.7±4.2 • K*011.5±4.4, 13.0±6.1, 9.2±1.3 •  p+< 5, 0.56 BABAR K0 40±8 evts B( K) slightly favors pQCD over QCDf. CP asymmetries also measured: consistent with 0.   Flavor Session VI: A. Telnov Patricia Burchat, Stanford

  23. “sin2a” Vtb*Vtd Vub*Vud a Patricia Burchat, Stanford

  24. B0 B0 CP Violation in B0 p+p- u b t d p- p- u d b u u p+ d d p+ d d |P/T| and relative phase d are unknown but can, in principle, be determined from an isospin analysis that requires measuring BF for B0p+p-, B0p+p-, B±p±p0, B0p0p0, and B0p0p0 •  CKM/CP Session II, N. Sinha (theory) Patricia Burchat, Stanford

  25. Expectations/Prejudices… • Measure coefficients for both sinDmDt and cosDmDt terms (Spp and Cpp ). • Spp and Cpp are determined by a, b, |P/T|, and d. Assume cf. Gronau and Rosner, Phys. Rev. D65, 093012 (2002)   CKM/CP Session I, Wang, Vahnsen Patricia Burchat, Stanford

  26. ~44M BB pairs ~60M BB pairs Belle B0 tags B0 tags B0 tags bkgdsubtracted Sππ= -1.21 +0.38 -0.27 +0.16-0.13Cππ= -Aππ=-0.94 +0.25 -0.31 ± 0.07 B0 tags BABAR qq and Kp background   CKM/CP Session II: Olsen, Sumisawa Sππ= -0.01 ± 0.37 ± 0.07Cππ= -0.02 ± 0.29 ± 0.07 Patricia Burchat, Stanford

  27. BABAR Belle Interpretation Patricia Burchat, Stanford

  28. Other studies of “sin2a” Belle B0 ’ KS • Penguin mediated. • Sensitive to new physics. • sin2a = 0.29 ± 0.54 ± 0.07 Many other studies of B (’)K (*) are being aggressively pursued. Challenge to theoretical models to explain relative rates. Patricia Burchat, Stanford

  29. sin2 Vub*Vud g Vcb*Vcd Patricia Burchat, Stanford

  30. Charmless Two-Body Decays In decays such as B  K p, interference between the Tree and Penguin amplitudes can lead to CP asymmetries that depend on g AND the strong phase difference. Also, ratios of BF for various p p and K p decay modes are sensitive to the angle g. Goal: Measure CP asymmetries AND branching fractions for all charmless two-body final states. Patricia Burchat, Stanford

  31. World average two-body results fromCLEO, Belle, BABAR Branching Fraction (10-6) CP Asymmetry p+p- 5.2±0.6 Cpp, Spp p+p0 4.9±1.1 (Belle 3.5s/BABAR 5.2s) p0p0 < 5.2, 5.6, 3.4 K+p- 18.6±1.1  K+p0 11.5±1.3  K0p- 17.9±1.7 K0p0 8.9±2.3 K+ K- < 1.9, 0.5, 1.1 K0 K0 < 13, 13, 7.3 incompatible at 3.3s level + 0.46 ± 0.15 ± 0.02- 0.17 ± 0.10 ± 0.02   CKM/CP Sessions I, M. Bona, II: B. Casey Patricia Burchat, Stanford

  32. Charmless Three-Body B Decays: why are they interesting? Sensitive to same weak phases as charmless 2-body decays. Dalitz plot analyses of 3-body decays can (eventually) be used to help disentangle relative strong phases. Already being done in charm decays. A long way to go in B physics, but we’re starting…   Charm Session I, D. Asner Patricia Burchat, Stanford

  33. All B+K+h+h-, B0Ksh+h- and BKsKsh modes being studied by Belle >4s signals in six of eleven 3-body modes being studied. Studying resonance substructure. Belle B+K+p+p- 237±23 events K*(892)0p+ and f0(980) K+ observed.   Flavor Session I, N. Gabyshev Patricia Burchat, Stanford

  34. 3-body branching fractions Branching Fractions (10-6) Belle BABAR p+ p+ p-<15 K+p+ p-55.6 ± 5.8 ± 7.759.2 ± 4.7 ± 4.9 K+ K+ K-35.3 ± 3.7 ± 4.534.7 ± 2.0 ± 1.7 K+ K± p ± no signal no signal Patricia Burchat, Stanford

  35. b c D0 u u K- s B- s b c K- B- u u D0 u u B  D(CP)K decays: why are they interesting? Potential for measuring CKM angle g: Determine g through amplitude relationships (up to discrete ambiguities): Gronau & Wiler; Dunietz (1991). Patricia Burchat, Stanford

  36. CP charge asymmetries in B  D(CP)K from Belle and BABAR: B-Dp B-DK Afl = + 0.003 ± 0.096 Dfl Afl = - 0.044 ± 0.059 (stat) ACP+ = + 0.29 ± 0.26 DCP+ ACP+ = + 0.16 ± 0.27 ACP- = - 0.22 ± 0.24 DCP-   Flavor Session V, G. Mancinelli DE (GeV) Patricia Burchat, Stanford

  37. Many highlights in hadronic B decays not covered here . . . B  D(*)+p-: potential for measuring sin(2b+g); See CLEO analysis of strong phase between DI = 1/2 and 3/2. Analysis of partially-reconstructed hadronic decays. B  Ds(*)+p- (Vub suppressed); help in interpretation of B  D(*)+p Color-suppressed B decays (e.g., B  D(*)0X0) B  D(*)D(*) (BF, ang analysis) B  baryons   Flavor Session V, T. Pedlar   Flavor Session V, M. Krishnamurthy, VI: C.S.Kim; CKM/CP Sesion III: Y. Zheng   Flavor Session V, T. Orimoto   FP Session I: Fang Fang (Belle); Cheng (theory) Patricia Burchat, Stanford

  38. Summary • With the rapidly increasing data samples from the B Factories, many new decay modes are becoming available for • time-dependent CP asymmetry measurements (sensitive to band a); • direct CP asymmetry measurements (sensitive to a and g); • branching fraction and resonant substructure measurements that are crucial for the interpretation of many of the CP asymmetries. • b is in agreement with SM predictions; too early to interpret results on a. • The summer conferences and the Fall papers will continue to bring many interesting new results to interpret as the B Factory experiments “catch up” on their analyses. Patricia Burchat, Stanford

More Related