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Advances in Direct CP Violation Studies at Belle: Rare Decays and Polarization Observations

This presentation discusses recent advancements in the study of direct CP violation (DCPV) at the Belle experiment. Key highlights include observations of rare decays such as B → Kπ and B → p0p0, alongside insights into polarization phenomena in decays involving K* states. Utilizing data from the KEKB accelerator, the research outlines novel techniques for background suppression and significance determination, and presents results from Khh Dalitz analyses. These findings contribute to our understanding of the complex behaviors in B meson decays and the implications for new physics.

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Advances in Direct CP Violation Studies at Belle: Rare Decays and Polarization Observations

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  1. Direct CP and Rare Decays June 21, 2005B Physics at Hadronic Machines, Assisi

  2. Outline • Machine, Detector, Basic Method • Direct CPV in Kp • Observation of p0p0 • Polarization in fK*, r+K*0 • Khh Dalitz Analysis • Baryonic Modes New Results only at LP05 and EPS

  3. Electron 8 GeV Positron3.5 GeV KEKB B-Factory Tsukuba Mt. 3Km Υ(4S) (10.58GeV/c2)  = 0.425

  4. Luminosity 1 fb–1 per day peak luminosity = 15.81 /nb/sec (May 18, 2005)

  5. Belle Detector

  6. e- e- e+ e+ B B B Signal Reconstruction In Υ(4S) rest frame: ∆E Mbc 1D-binned fit 2D-unbinned fit

  7. Main background for hadronic rare B is continuum qq events. (q=u,d,s,c). Topology of continuum events and B decays are different. Choose |cosθThrust| S⊥ R2so R4so R2oo R3oo R4ooas input to Fisher, and combine it with cosθBto calculate the Likelihood Ratio. Define modified Fox-Wolfram moment: Use Fisher discriminant to optimize the coefficients. Υ(4S) B decay continuum events Background Suppression

  8. Likelihood Ratio (LR) Optimize uds charm off reson. sideband

  9. Evidence for DCPV in B Kp Y. Chao, P. Chang et al. PRL 2004 CLEO 1999 (PRL 2000) 253 fb–1 214053 evts ACP(K+p–) = –10. 1 ± 2.5 (stat) ± 0.5 (syst) % w/ BaBar > 5s 3.9s

  10. AKp, AppSizable Ali @ ICHEP2004 Belle SU(3) relatesApp= -3AKp (Gronau & Rosner) BaBar Sizable T-P Strong Phase

  11. AKp0≠AKp? Y. Chao, P. Chang et al. PRL 2004 253 fb–1 72834 evts ACP(K+p0) = 4 5  2% 2.4s from K+p- (3.6sw/ BaBar) Large EWPenguin? Large C ? d p0 _ d b s B- K- u u

  12. Observation of B0p0p0 Y. Chao, P. Chang et al. PRL 2005 253 fb–1 8216 evts B = (2.32 ) x 10-6 0.44 0.48 0.22 0.18 5.8 s Use same flavor-tagging as TCPV analysis ACP = 4417% 53 52 Main limiting factor for f2 program from pp

  13. Polarization in B  fK* fK* polarization anomaly? But …?

  14. Polarization in B  fK* K.F. Chen et al., hep-ex/0503013, to appear PRL 253 fb–1

  15. fK* Polarization transversity basis Naively

  16. Angular Analysis for fK* Polarization Confirm fL ~ 0.5 4.3sevidence for FSI (strong phase)

  17. New Physics Test with fK* Polarization T-odd CPV Datta & London 2004

  18. More Observables with fK* Polarization

  19. Polarization in B  r+K*0 J. Zhang et al., hep-ex/0503013, submitted PRL 253 fb–1 (2-d unbinned fit projections) Non-resonant r+K+p– Significant Take into account in Angular Analysis

  20. Angular (fL) Analysis for r+K*0 helicity basis A0 A± NR-rKp Another pure-PfL ~ 0.5

  21. KhhDalitz Analysis Summary A. Garmash et al., hep-ex/0412066, submitted PRD 140 fb–1

  22. Model Kππ-AJ: SAJ(Kππ) = A1(K*(892)) + A0(K*0(1430)) + AJ(fX(1300)) + A0(cC0) + A1(ρ(770)) + A0(f0(980)) B+ K+π+π-: Model Fitting to Signal L=140 fb-1 Model Kππ-A0 Model Kππ-A0 fit the data with different spin assumptions

  23. Model KKK-BJ: Helicity angle distributions: SBJ(KKK) = A1(φ(1020)) + AJ(fX(1500)) + A0(cC0) + ANR ANR Parameterizations used: ANR(s13,s23) = a1(e-βs13 + e–βs23)eiδ fX(1500) is best fit with the scalar hypothesis B+ K+K+K-: Model Fitting to Signal L=140 fb-1 Model KKK-B0 ANR(s13,s23) = a1eiδ ANR(s13,s23) = a1[(1/s13)b+ (1/s23)β]eiδ Model KKK-B0 fX(1500) φ(1020)

  24. Null asymmetry tests: • qq related background: ACP(qq)=(-0.83±1.30)% • BB related background: ACP(BB)=(-1.15±2.18)% • B->Dπ->Kππ signal: ACP(Dπ)=(-1.16±0.86)% Search for DCPV in B± K±π+π- 253 fb–1 3115±92 evts N(B-) = 1637±68 N(B+) = 1492±65 preliminary N(K-π-π+) – N(K+π+π-) ACP(K±π+π-) = = (+4.6±3.0 ) % +1.7 -1.2 N(K-π-π+) + N(K+π+π-) Considered as a systematic error due to detector asymmetry

  25. DCPV Hint in B+ ρ0K+ 253 fb–1 A 2.4σ hint for Direct CP violation in B±->ρ(770)0K± preliminary ACP(ρ0K±) = 27 ± 12 ± 2 % +59 - 3

  26. Improved B+  ppK+ Measurement M.Z. Wang et al., PLB 2005 140 fb–1 21717 evts Threshold Peaking BF: 4.59 ± 0.50 x 10-6 (4.89 x 10-6, PRL92, 131801, 2004) Two-body not yet seen. +0.38- 0.34

  27. B0 LL, Lp, pp and other 140 fb–1 M.C. Chang et al. PRD 2005 90% confidence level UL: B0pp< 4.1 x 10-7 B0Lp< 4.9 x 10-7 B0LL< 6.9 x 10-7 Belle:B+ J/pL < 4.1 x 10-5 BABAR:B+ J/pL< 2.6 x 10-5 B+ J/pp<1.9 x 10-5 BABAR, 81fb-1 Belle, 78fb-1

  28. threshold peaking threshold peaking Threshold Peaking: ppKs &pLp

  29. Angular Distribution: ppK+ p Өp X K+ bs dominant process Fragmentation picture p at pp rest frame s u K+ p u d u u s u u d p ppK signal Proton against K- (p against K+) : flavor dependence! (Expect symmetric distribution if effective 2-body)

  30. Outline • Machine, Detector, Basic Method • Direct CPV in Kp • Observation of p0p0 • Polarization in fK*, r+K*0 • Khh Dalitz Analysis • Baryonic Modes New Results only at LP05 and EPS

  31. Backup

  32. Previous B+ ppK+,ppp+Measurement M.Z. Wang et al., PRL 2004 78 fb–1 Threshold Peaking

  33. ppp+< ppK+

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