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EW Penguin & Leptonic B decays

EW Penguin & Leptonic B decays. Youngjoon Kwon. Prologue: Introduction & History Modes w/ 0 n ’s Modes w/ 1 n ’s Modes w/ ≥2 n ’s Summary & Prospects. Overview. Physics Goals of B-factories. Establish CP violation in B decays and over-constrain the SM picture of CP violation

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EW Penguin & Leptonic B decays

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  1. EW Penguin & Leptonic B decays Youngjoon Kwon • Prologue: Introduction & History • Modes w/ 0 n’s • Modes w/ 1 n’s • Modes w/ ≥2 n’s • Summary & Prospects Overview

  2. Physics Goals of B-factories • Establish CP violation in B decays and over-constrain the SM picture of CP violation • any inconsistency? • Measure fundamental parameters of SM • 10 (out of 18, not counting neutrino masses, yet) parameters are related with quark flavors • CKM triangle parameters; angles&sides • Search for rare / forbiddendecays and explore new physics effects FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  3. Motivation for Rare B decays • SM is a very good approximation to reality. i.e., for most processes • Need to consider processes where is small in order to be sensitive to new physics. (Ex.)processes dominated bypenguin loops • Compare Nature (exp.) with SM prediction for those sensitive processes • Find New Physics or learn new lessons FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  4. History 1 EMPenguins First penguin observation CLEO, PRL 1993

  5. History 2 Electroweak Penguins First EW Penguin observation by Belle, PRL 2002

  6. Contents • 0n final states Full recon. of signals • B  l+l- • B  Xs l+l- • 1n final states n-recon. using (E,p)miss • B  l n • B  l ng • Final states w/ ≥2n Full recon. of “other B” • B tn • B  K(*) nn, “nothing”

  7. zero-n modes– straightforward by full-recon. of signal B – hermeticity is still used to suppress Xln backgr. Similar penguins, rotated by 90o EW penguin, mostly

  8. Overview • penguins (g, Z) and W-box contribute • sensitive to C9, C10 & sgn(C7) ( |C7| from bsg) • rich structure • q2 distribution • Forward-Backward asymmetry FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  9. Overview AFB K* l+ l- Ali et al. PRD (2000) SM q2 B : measured in the l+l- frame FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  10. First measured by Belle: PRL (2003)w/ 60fb-1 pseudo-reconstruction of the Xs system combine K  or KS with (0~4)p (n(p0)≤1) L-fit Mbc for signal yield peaking background component J/y, y(2S): vetoed by m(l+l-) B  Xsp+p- is subtracted, weighted by fake rate combinatorial backgr. comp. mostly from double-semilept. B decays + some from conti. suppressed by combining variables into a likelihood ratio Fitted (Mbc) using shapes from Xsem Beam-constrained mass: Inclusive FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  11. NBB=89M FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  12. 3210 Xse+e- 369 Xsm+m- 6814Xsl+l- Xse+m- control sample 5.8s significance NBB=152M Belle-Conf-0414  then, extrapolated FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  13. K* K Differential distributions K, K* states are clearly seen / consistent w/ SM FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  14. Exclusive B  K(*) l+l- first observed by Belle in 2001 (29/fb) first >3sevidence by BaBar(81/fb) first observed by Belle in 2003(140/fb) • Main backgrounds • B  J/yK(*), etc. veto! • B  K*g(conversion), B  K*p0  m(e+e-) > 0.14 GeV • combinatorial from semileptonic, continuum • B  K(*) p+p- (pm fake ~2%)2 FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  15. B  K(*) l+l- update NBB=273M NBB=123M FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  16. is assumed to compensate for q2=0 pole for K*e+e- factor 0.75 & SM values from Ali, et al. BF(B  K(*) l+l-) Belle-Conf-0415 [Note] NNLO by Ali, et al. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  17. more than just BF for B  K(*)l+l- • rich structure: sensitive to C9, C10 & sgn(C7) • q2 distribution • Forward-Backward asymmetry • Ratio of BF’s (ee vs. mm) • Kl+l- : sensitive to H0 in 2HDM (=1 in SM) FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  18. q2 for B  K(*)l+l- • dq2 /q2 ~ 0.6% • Yellow bands show ranges of theoretical predictions. • Both results are consistent with the SM prediction. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  19. Belle-Conf-0415 AFB (q2) for B  K(*)l+l- • Raw AFB in each q2 region is extracted from Mbc fit. • Dotted lines indicatecharmonium veto windows. • Kll has no asymmetry, hence a good control sample. • Curves (not fitted lines!)show theory including exp’tal efficiency. • Both are in agreement with data. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  20. Leptonic decays • Highly suppressed in the SM • by CKM & GIM • SM: BF(Bs(d)m+m-)= 3.5x10-9 (1.0x10-10) • New physics potential • Tree: SUSY w/ RPV • Loop: MSSM, mSugra, 2HDM, etc. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  21. Belle/BaBar NBB=85M NBB=123M FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  22. CDF/D0 These limits start to restrict SUSY SO(10) models FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  23. one-n modes W-annihilation; crucial for fB Not as clean, but could be interesting/useful • A missing neutrino in the final state,  full recon. of signal B is not possible • Use hermeticity and neutrino mass constraint  (E,p)miss for neutrino 4-momentum

  24. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  25. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  26. Belle/BaBar BaBar, PRL (2004) Belle, prelim. Belle-Conf-0429 FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  27. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  28. Belle FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  29. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  30. Belle FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  31. Belle-Conf-0429 FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  32. modes with ≥2 n’s Belle/BaBar BaBar Searches for these modes use full reconstruction of the other B

  33. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  34. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  35. B  t n Belle (for example) FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  36. FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  37. Belle-Conf-0428 FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  38. B  t n BaBar • Two methods for kinematic tagging a. Hadronic full-recon taghigh purity NBB=89M FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  39. B  t n BaBar b. semileptonic partial-recon taghigh stat - some ambiguity, trading purity for statistics - require in the physical region NBB=124M combining the two methods, FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  40. B  K n n FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  41. B  “invisible” (nn), nng FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

  42. Summary • Electroweak penguin decays B  Xs l+l- • Firmly established in both exclusive & inclusive measurements • Measurements (BF, q2, m(Xs)) are consistent with SM • First attempt to measure AFB as a function of q2 in exclusive modes, K l+l- & K* l+l- consistent with SM • Much improved limits in the leptonic B decays • Approach w/in 1 order of mag. to SM for B  ln(g), tn 2 orders of mag. to SM for B  l+l- • Limits for other exotic modes: B  (nothing)(X) FPCP 2004, Oct. 4 - 9, 2004, Youngjoon Kwon (Yonsei Univ.)

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