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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

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

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  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

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