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Rare Hadronic B Decays

Rare Hadronic B Decays. John Fry Lepton Photon 2003. Scope of Talk. To present updated branching fractions (BF) and CP asymmetries (A CP ) for rare (charmless) B decay modes

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Rare Hadronic B Decays

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  1. Rare Hadronic B Decays • John Fry • Lepton Photon 2003

  2. Scope of Talk • To present updated branching fractions (BF) and CP asymmetries (ACP) for rare (charmless) B decay modes • To show how BF and ACP are used with theoretical models to put constraints on the Standard Model and to search for New Physics. NB: All results are preliminary unless referenced. John Fry Lepton Photon 2003

  3. How Good is the Standard Model? • LEP • Coupling Constants • CPLEAR • T consistent with CP • Tight CPT constraint K [K] and B sectors [md, Vub , Vtd , Sin (2)] consistent with each other and SM (theory) A. Höcker et al, Eur. Phys. Jour. C21 (2001) 225, [hep-ph/0104062] John Fry Lepton Photon 2003

  4. Motivation for Rare Decays • SM is a very good approximation to reality Hence • Need to consider processes where is small in order to be sensitive to new physics. • Hence processes dominated by penguin loops, or CKM- suppressed decays John Fry Lepton Photon 2003

  5. Procedure • Compare nature (precise, experimental measurements) with SM (theoretical models) for sensitive quantities. • Agreement gives an alternative route to (, ) and additional constraints on the unitarity triangle. • Disagreement means: • New Physics …. OR • Refinements needed to theoretical calculations … ….AND Model-independent calculations needed John Fry Lepton Photon 2003

  6. M1 B M2 The (theoretical) Problem How to go from here … to branching fractions and CP asymmetry John Fry Lepton Photon 2003

  7. Classes of theoretical calculations • QCD Factorisation (mb >> QCD) Amps factorise to LO (/ mb), all orders S Naïve factorisation recovered in LO • Phenomenology Amplitudes of dominant processes related to measured BF and each other via SU(3) • Model “Independent” Isospin & minimal dynamical assumptions  bounds on deviations from SM Beneke, Buchalla, Neubert & Sachrajda Nucl Phys B606 (2001) 245 Beneka & Neubert Hep-ph / 0308039 Chiang, Rosner Phys Rev D65 074035 Chiang et al Hep-ph / 0307395 Lipkin Phys Lett B254 (1991) 247 Grossman, Ligeti, Nir, Quinn Hep-ph / 0303171 John Fry Lepton Photon 2003

  8. M B m m M B  T B + T F M m <MmQB> = FBm T * fM M + FBM T * fm m + T fB B* fM M* fm m Visualising QCD Factorisation  John Fry Lepton Photon 2003

  9. T T F m M B B + M m + Pictorial Phenomenology  Leading Order – Naive Factorisation John Fry Lepton Photon 2003

  10. : strong phase CP-even : weak phase CP-odd Naïve Expectation: ACP small for K (0+)Dominant penguin (tree) ACP large for -+Unless dynamically suppressed Direct CP Violation CP asymmetry occurs if the decay B  f ( and its charge conjugate) is mediated by two amplitudes with different strong and weak phases: John Fry Lepton Photon 2003

  11. PEP-2 (SLAC) = B B rec = flav B B rec Signal Flavor eigenstates Resolution function and Tagging Signal: Branching fraction; ACP; CP Analysis Overview of B Production and Decay Exclusive B Meson Reconstruction CP eigenstates Flavor eigenstates Inclusive Reconstruction B-Flavor Tagging John Fry Lepton Photon 2003

  12. (DE)  20 MeV s(mES)  2.6 MeV/c2 Signal Selection John Fry Lepton Photon 2003

  13. B produced (almost) at rest in Y(4S) frame Isotropic B Jetty Continuum Combine into a Fisher (or NN) Monte Carlo u,d,s,c background Signal Arbitrary Units Fisher Discriminant Discrimination of B and Continuum John Fry Lepton Photon 2003

  14. Search for B0 → p pbar @ BaBar Use the DIRC to reject K, p, e, m Signal Eff = 91% Background Eff = 3% K,p, e, m Total signal efficiency = 37% p Smallest upper-limit BF in B0/B decays! John Fry Lepton Photon 2003

  15. John Fry Lepton Photon 2003

  16. John Fry Lepton Photon 2003

  17. Summary of BF (10-6) for K,  and KK John Fry Lepton Photon 2003

  18. HFAG J Smith (Colorado) J Alexander (Cornell) John Fry Lepton Photon 2003

  19. Belle 152 106 BB 140 fb-1 Signal 3.4  25.6 BF (10-6) 1.7 ± 0.6 ± 0.2 Belle +9.3 -8.4 Belle John Fry Lepton Photon 2003

  20. BaBar 124 106 BB 113 fb-1 Signal 4.2  46 ± 13 ± 3 BF (10-6) 2.1 ± 0.6 ± 0.3 BaBar 0 0 Sub to PRL John Fry Lepton Photon 2003

  21. QCD_F: Ratios of  & K BF’s Data (2001) BBNS NPB606 (2001) 245 Inconsistent ? Data (2003) 0.42 ± 0.11 John Fry Lepton Photon 2003

  22. † Belle: -8.8 ± 3.5 ± 1.8 BaBar -10.7 ± 4.1 ± 1.2 ‡ Keum and Sandahep-ph/0306004 Beneke and Neubert hep-ph/0308039 Comparison of BF and ACP with Theory‡ John Fry Lepton Photon 2003

  23. Belle John Fry Lepton Photon 2003

  24. Disentangling the Bh+h- contributions (I) Monte-Carlo plot below shows: Bdp+p-,Bs K+K- BsK±p±, & BdK±p± (From Monte-Carlo) all pile up in the same region B h+h- from hadronic trigger Includes Bdpp, BsKK,BsKp,and BdKp CDF Must disentangle contributions from each mode To do this we use: -Kinematicalvariable separationM vs a=(1-p1/p2)q1 -dE/dx based K and p identification John Fry Lepton Photon 2003

  25. Disentangling the Bh+h- contributions (II) dE/dx calibration using D*± D0p, D0 K±p ±(p from D* unambiguously distinguishes K, p from D0) Mpp vs a for each Bh+h- mode Sanity check: Measure Ratio of Branching Ratios CDF :G(Bd p+p-)/G(BdK+p-) = 0.26 ±0.11±0.055, PDG: Method works ! Confirmed by Sanity check against ratio of branching ratios Have first observation of Bs K+K- Its a CP Eigenstate: Can use this To measure DGs as well !! Yield for each mode: Bd p+p- 14817 Bd K±p± 3914 Bs K± p± 311 Bs K+K- 9017(stat) 17(stat) First observation ! CDF John Fry Lepton Photon 2003

  26. Disentangling the Bh+h- contributions (Blessed CDF results) • ACP(BdKp) = 0.02 ± 0.15(stat) ± 0.017(syst) • BR(Bdpp)/BR(BdKp) = • 0.26 ± 0.11(stat) ± 0.055(syst) • fs X BR(BsKK)/fd X BR(BdKp) = • 0.74 ± 0.20(stat) ± 0.22(syst) • Yield of BsKK = 90 ±17(stat) ±17(syst) events John Fry Lepton Photon 2003

  27. No sign of rescattering (FSI) yet Is Rescattering Important? BF(10-6) *Chen and Li, Phys. Rev D63, 014003 (2000) • Could modify branching fractions and CP asymmetries in pp and Kp decays, complicating extraction of a and g • KK decays are more sensitive to rescattering • Could have significant enhancement through (for example) DD or pp intermediate states John Fry Lepton Photon 2003

  28. BF & ACP for B , K, , K John Fry Lepton Photon 2003

  29. Belle B  , K K+ + KS John Fry Lepton Photon 2003

  30. BaBar:B  K Dalitz Plot Branching Fractions 10 -6 K*0(892) 56.4 fb-1 K*0(higher) -2.7 D0 -2.6 ρ0 f0(980) -5.7 c0 John Fry Lepton Photon 2003

  31. Belle: Dalitz Plot Amplitude Analysis 140 fb-1 B+ K+K+K- (Signal 1400) and K++ - (Signal 2584) Resonances: K++ - K*(890), K*(1430), (770), c0(3400), f0(980), X(1350) K+K+K-(1020), C0(3400), X(1500) Background parameterisation – fitted with large (7*) sideband sample Signal parameterisation – fix masses, widths except X, f0 Fit to signal + background and determine amplitudes and phases John Fry Lepton Photon 2003

  32. John Fry Lepton Photon 2003

  33. Belle DP Mass and Helicity Projections K John Fry Lepton Photon 2003

  34. Belle Branching Fractions from Dalitz Plot John Fry Lepton Photon 2003

  35. HFAG J Smith (Colorado) J Alexander (Cornell) John Fry Lepton Photon 2003

  36. B0 +  - NS = 93 ±22±9 BaBar [> 5] Cos(1) MES   Longitudinal Polarisation B → V V fL = L /  100% Pol  CP even Expect: fL ~ 1 – O(M2V/M2B) John Fry Lepton Photon 2003

  37. Belle B  + 0 John Fry Lepton Photon 2003

  38. B → ρρ and ρ K*[BaBar &Belle] • CP asymmetries consistent with zero • Polarisation in agreement with expectation John Fry Lepton Photon 2003

  39. Why we need Theorists p+p0 K0p+ The VPSTE effect(Form factor corrections at 40% level) John Fry Lepton Photon 2003

  40. Grossman Quinn bound PRD 58 (1998) 017504 | - Eff| < 50o () and < 20o () at 90% CL + - is dominantly longitudinal polarised, CP-even final state The unique decays B 0 0 and 0 0 BF give model-independent limits to the CP angle  John Fry Lepton Photon 2003

  41. B   K(*)BaBar &Belle • Expect similar BF all modes • BF(+) < 4 10-7 [90% CL] • No indication for rescattering – as KK • Polarisation unexpectedly small  q s B+,0 q s K(*) u u John Fry Lepton Photon 2003

  42. Belle John Fry Lepton Photon 2003

  43. BR(B±fK±) at CDF • BR(B±fK±) /BR(B±J/y K±) = 0.0068 ±0.0021 (stat.) ± 0.0007 (syst.) • Using PDG 2002 for BR(B±J/y K±): • BR(B±fK±) = (6.9 ± 2.1 (stat.) ± 0.8 (syst.)) x 10-6 John Fry Lepton Photon 2003

  44. B  (')K(*) and ('),  BaBar and Belle John Fry Lepton Photon 2003

  45. K, hK* enhanced Interference K, K* suppressed Theoretical background: (')K, K * modes H Lipkin Phys Lett B254 (1991) 247 CKM suppressed Flavour singlet diagram: Also important for K* Similarly for K 0, K *0 except no external tree John Fry Lepton Photon 2003

  46. John Fry Lepton Photon 2003

  47. Large asymmetry predicted for + , small for + Chiang, Gronau, Luo, Rosner and Suprun [hep-ph/0307395] B  (')K(*) and ,  BaBar and Belle John Fry Lepton Photon 2003

  48. HFAG J Smith (Colorado) J Alexander (Cornell) John Fry Lepton Photon 2003

  49. HFAG J Smith (Colorado) J Alexander (Cornell) John Fry Lepton Photon 2003

  50. How does theory stack up? • Good phenomenological understanding of Branching Fractions for 2-body PP and PV decays [Chiang et al hep-ph/0307395; Beneke et al hep-ph/0308039; Keum et al hep-ph/0306004] • Factorisation models give insight into dynamics, but: • BF for 0 0 looks to be in disagreement with all predictions • BF for K, ' K,  K* final states underestimated in QCDF [Annihilation contribution may be too large Aleksan et al, hep-ph/0301165] • Asymmetry data is not yet precise enough to test models • There is still a considerable role for model-independent theoretical calculations John Fry Lepton Photon 2003

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