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D alitz Plot Analysis in the Charmless three-body B decays

D alitz Plot Analysis in the Charmless three-body B decays. @. Gagan Mohanty University of Warwick. Representing. Outline of the talk. Introduction Theoretical Framework Experiment & Dataset Event Selection DP Analysis Methodology Results and Discussion Conclusions and Outlook.

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D alitz Plot Analysis in the Charmless three-body B decays

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  1. Dalitz Plot Analysis in the Charmless three-body B decays @ Gagan Mohanty University of Warwick Representing

  2. Outline of the talk • Introduction • Theoretical Framework • Experiment & Dataset • Event Selection • DP Analysis Methodology • Results and Discussion • Conclusions and Outlook (*) DP = Dalitz Plot Gagan Mohanty

  3. Introduction: Timeline (1993) • 1st observation of charmless B decays by CLEO PRL 71, 3922 (1993) • Since then… Gagan Mohanty

  4. Introduction: Timeline (2006) • A vast amount of results in the charmless sector is pioneering: BaBar: PRL 93, 131801 K+π- • test of QCD factorization • direct CP • search for new physics K-π+ • A natural extension: quasi-two-body B decays to three-body final states Gagan Mohanty

  5. Theoretical Framework • The dominant contributions to charmless three-body final state: b → s/d b→s penguin transition contributes only to final states with odd number of kaons due to presence s quark e.g. Kππ, KKK b→u tree and b→d penguin transitions contribute mainly to final states with even number of kaons such as πππ, KKπ. Contribution to odd number kaon states is Cabibbo suppressed [~ sinθc] b → u “wrong flavor” final states such as K+K+π- and K-π+π+ are expected to be exceedingly small at o(10-11) in the Standard Model, and offer an excellent window for new physics Gagan Mohanty

  6. Typical final states • Shall focus on the Dalitz Plot analysis of above five charmless three-body decay modes from BaBar Gagan Mohanty

  7. PEP-II asymmetric B factory 9 GeV e-→Υ(4S)← 3.1 GeV e+γβ = 0.56 <Δz> ~ 260 μm This talk includes Daily luminosity Lint > 300 fb-1 (10% off-peak) Run 5 Gagan Mohanty

  8. ~ 3x Design = 3x1033 cm-2 sec-1 Design ~ 100 pb-1 Gagan Mohanty

  9. High quality tracking (fiducial volume: 041 <  < 2.54) (pT)/pT = 0.13% PT 0.45% BaBar Detector Electromagnetic Calorimeter 6580 CsI(Tl) Crystals 1.5Tsolenoid Cerenkov Detector (DIRC) 144 Quartz bars and 11000 PMTs • e ID • reco. E/E = 2.32% E-1/4  1.85% Particle ID e+ (3.1GeV) DriftChamber 40 layers e- (9GeV) InstrumentedFluxReturn ResistivePlateChamber → Limited StreamerTube SiliconVertexTracker 5 layers, double strip  & KL ID Gagan Mohanty

  10. Event Selection • Wish to select B → hhh (h=K/π) event out of sea of continuum and other type B events • Done in several steps: • Continuum rejection (Event topology) • πvs.Kvs. e/μ (Particle flavour Identification) • Reconstruct Ks/π0 from their decay products • onvs.off resonance (Kinematical variables) • Veto on charmed resonances: D, J/ψ, ψ(2S) Gagan Mohanty

  11. Continuum Rejection • B’s are produced at rest (spherical) vs. jetty udcs events • Cuts on event thrust & Fisher discriminant/NN constructed out of the topological variables Signal Background Gagan Mohanty

  12. Particle Identification • PID is crucial for the analyses • distinguish Kvs.π(DIRC) • veto the electron (DCH/EMC) • Reconstruct π0[→γγ] (EMC)and Ks[→ ππ] Gagan Mohanty

  13. Kinematical Variables B+→ K+π+π- • Utilize precise beam energy information & (E,p) conservation Signal box Sideband Background DP fit Gagan Mohanty

  14. DP Analysis Technique – 1 • Dalitz Plot is a powerful technique relying on Lorentz invariant phase-space variables in a three-body decay 1 sij = m2ij 2 B + 2 3 1 {13} Resonance 3 B Gagan Mohanty

  15. DP Analysis Technique – 2 • Extract ci and θi by performing a max likelihood fit • θi has two terms: • CP violating weak phase (–ve) • CP conserving strong phase same { B → B • Separate fit of B and B samples Gagan Mohanty

  16. Efficiency Variation B+→ π+π+π- D J/ψ ψ(2S) • Smooth variation of efficiency across the DP • Use 2D parameterization in the likelihood fit • Combinatorics is very small (mostly ignored) Gagan Mohanty

  17. Background Parameterization B+→ π+π+π- D Continuum J/ψ ψ(2S) • Use 2D histogram to model the DP distribution • Continuum = off res + on res data sideband and B bkg = Monte Carlo & subtracted from latter • Square DP for better describing peaking edge Gagan Mohanty

  18. B+→ π+π+π-: fitting the signal PRD 72, 052002 (2005) ρ(770) B+ f2(1270) 210 fb-1 Coupled BW ρ(770) B- f2(1270) Phase-space Gagan Mohanty

  19. B+→ π+π+π-: Summary • ρ0(770) is the dominant component • 3σ indication for f2(1270) & NR mode • Little evidence for σ (seen by BES) PRD 72, 052002 (2005) • Can be utilized to measure γ PRL 81, 4067 (1998) Gagan Mohanty

  20. B+→ π+π+π-: prospect for γ • proposes to use B→χc0π,which carries a null weak phase, as the reference mode • However, no indication of the χc0πmode • new reference mode needs to be studied • Iso-scalar ππresonances e.g. f0(980) are proposed as alternatives • Again statistics disallows any meaningful conclusion • Lint is the need of the hour! PRL 81, 4067 (1998) Gagan Mohanty

  21. B+→ K+π+π-: fitting the signal PRD 72, 072003 (2005) Fit qq BB B- B- 205 fb-1 B+ B+ Gagan Mohanty

  22. B+→ K+π+π-: Summary PRD 72, 072003 (2005) • Total BF differs significantly from Belle • (Kπ)*0=>K*0(1430) resonance + Effective range NR component (again different in Belle) • Evidence for direct CP violation in ρ0(770)K mode Gagan Mohanty

  23. CP in charged B decays? • Large ACP in agreement with predictions based on global SU(2) fits |T/P|~0.3 PRD 72, 072003 (2005) BABAR PRD 69, 034001 (2004) Belle • Eagerly looking forward to more data… hep-ex/0512066 (2005) Gagan Mohanty

  24. B0→ π+π-π0: time-dependent DP • Parameterize B0(B0) → π+π-π0 amplitude in terms of ρ+(→π+π0)π-,ρ-(→π-π0)π+and ρ0(→π+π-)π0 PRD 48, 2139 (1993) } fκ(κ = +,-,0) areBW functions dependent on the DP variables • Time-dependent decay rate: { • Determine Uκ and Iκ (27 →16 parameters for small ρ0π0 contribution) in the likelihood fit Gagan Mohanty

  25. B0→ π+π-π0: DP fit and result • Likelihood built using PDFs for the discriminating variables: ΔE, mES, NN, Δt & DP variable (square) hep-ex/0408099 (2004) m’ θ’ 192 fb-1 Event yield = 1184 ± 58 • Extract physics parameters from the fitted Uκ and Iκ: { Gagan Mohanty

  26. B0→ π+π-π0: α and direct CP hep-ex/0408099 (2004) { 1 2 Direct CP violation @ 2.9σ level Gagan Mohanty

  27. Overall  from BaBar a from rr, rp and pp • from a full CKM fit (eK, Vub, Dmd,s, sin(2b)) • Mirror solutions being disfavored! • rpmode particularly plays an important role • From rr, rp, pp (combined): (preliminary) Gagan Mohanty

  28. B0→ K+π-π0: fitting the signal hep-ex/0408073 (2004) Fit qq BB • Gounaris-Sakurai • LASS shape • Uniform phase-space PRL 21, 244 (1968) NP B296, 493 (1988) Gagan Mohanty

  29. B0→ K+π-π0: Summary hep-ex/0408073 (2004) 193 fb-1 • 4.2σ evidence of K*0(892) mode, UL from Belle • Negligible non-resonant contribution 90% CL UL • Measured BF of the benchmark process B0→ D0π0 in agreement with current world average: (270 ± 80)x10-6 • No significant ACP observed in any of the modes Gagan Mohanty

  30. B0→ K+K-Ks: fitting the signal • 1st attempt to study the K+K-Ks Dalitz plot • Narrow Φ(1020) signal => use convoluted BW • Handful events to claim any other resonances • Try combinations of known 0++ and non-flat NR model to best parameterize the data f0(980) 210 fb-1 X(1500) NR Gagan Mohanty

  31. f reflections f D+,Ds+ X(1500) cc0 NR B0→ K+K-Ks: Summary hep-ex/0507094 (2005) • Ad hoc model to describe S-wave • Need theory hand & more data Gagan Mohanty

  32. Summary • Charmless three-body decays move to the era of Dalitz plot analysis • Branching fractions of many quasi-two-body decays are measured, some are the 1st time measurements • Evidence of large CP asymmetry in the ρ0(770)K mode of the Kππ final state • Time-dependent Dalitz measurement of B0→(ρπ)0 • direct CP violation at 2.9σ level and measured α • Mostly covered from BaBar, competitive results are available from Belle for many modes Gagan Mohanty

  33. Backup Slides Gagan Mohanty

  34. Future Prospects Double again from 2006 to 2008 ~ 1 ab-1 Double from 2004 to 2006 Lint [fb-1]  Gagan Mohanty

  35. Square Dalitz Plot ρ- ρ0 ρ+ Jacobian “blow up” r bands & interference regions Gagan Mohanty

  36. B→πππ: nominal fit results PRD 72, 052002 (2005) Gagan Mohanty

  37. B→Kππ: nominal fit results PRD 72, 072003 (2005) Gagan Mohanty

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