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Time-Dependent CP Violation Measurements in B-Meson Decays at BABAR and Belle

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aletha
60 diapositives · 727 Views · Sep 19, 2014

This study presents new measurements of time-dependent CP violation (TCPV) in B-meson decays at the BABAR and Belle experiments. Focusing on hadronic B-meson decays involving penguin diagrams, the research highlights results such as B0 → K0K0, K+K−Ks, and B0 → K*(0)g. The findings provide significant insights into TCPV and its implications for the Standard Model, showcasing preliminary results that underscore the capabilities of B-factories. Related presentations discuss the theoretical background and future prospects in TCPV research.

#time-dependent cp violation measurements in b-meson decays at babar and belle #time-dependent cp violation measurements in b-meson decays at babar and belle ppt #powerpoint #presentation
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Time-Dependent CP Violation Measurements in B-Meson Decays at BABAR and Belle
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  1. Search for New Physics Phasesin b g s PenguinsTime-dependent CP Violation (TCPV)Measurements at BABAR and Belle M. Hazumi (KEK) FPCP2004, Oct. 4-9, Daegu, Korea

  2. 3-body decays with no need for angular analysis Outline • TCPV in hadronic bgs penguins • ICHEP04 results for B0gfK0, K+K-Ks, hKs, f0(980)Ks, wKs, Ksp0 • TCPV inradiative bgs penguins • ICHEP04 results for B0gK*0g, K*0gKsp0 • Summary - New results for B0gKsKsKs from Belle - New results for B0gKsp0g(including K*0g) from Belle All results are preliminary. Masashi Hazumi (KEK) FPCP2004

  3. Related talks • Theory in and beyond the Standard Model (SM)  E. Kou, P. Ko, Y. Okada, … • Basics of TCPV measurements  K. Trabelsi • Rare B decay reconstruction and background suppression  Several speakers • Future prospects  Y. Kwon, T. Iijima Masashi Hazumi (KEK) FPCP2004

  4. http://www.physics.purdue.edu/10E34/ TCPV in hadronic bgs penguins • TCPV in fKs already ranked as observable • fKs not yet observed (needless to say, no TCPV measurement) as of June.2000 Masashi Hazumi (KEK) FPCP2004

  5. sin2f1 from bgs penguins at ICHEP04 sin2f1(bgsqq) = 0.43  0.08 sin2f1(bgccs) = 0.726  0.037 CL = 3.410-4 (3.6s) My “optimistic” guess in 2000 underestimated the ability of B factories ! Masashi Hazumi (KEK) FPCP2004

  6. _ f ~ pure ss l2 l3 l1 _ u u f • Small SM “tree pollution” • CKM-suppressed: O(l2) • OZI-suppressed: O(10-1) • u-penguin (l4) also highly suppressed (simplified explanation) B0f K0 : K0gKs or KL (C -A alsoused) S-CPsin2f1, A 0 if no new CPV phase CP : CP eigenvalue -1 for fKs +1 for fKL “sin2f1” -CP S Masashi Hazumi (KEK) FPCP2004

  7. [hep-ex/0409049] [hep-ex/0408072] _ 227M BB _ 275M BB fKL: fgK+K- KL w/ ECL or KLM fKL: fgK+K- KL w/ EMC or IFR Events/(50MeV/c) sig + bkg_sum bkg_sum sig + B-bkg B-bkg B0fK0signals Plots for all signal events Nsig: the total number of signal events in the sample used for TCPV measurements fKs: fgK+K- Ksgp+p-, p0p0 Nsig = 13914 purity = 0.63 fKs: fgK+K- Ksgp+p- Nsig = 11412 Plots for signal-enhanced regions: signals seen in the plots < Nsig; Dt used for selection. purity = 0.17 Nsig = 9818 Nsig=3615(stat)10(syst) Masashi Hazumi (KEK) FPCP2004

  8. [hep-ex/0408072] [hep-ex/0409049] “sin2f1” = +0.50 0.25 A = 0.00 0.23 0.05 _ 275M BB _ 227M BB S = 0.73 fKL fK0 fKs fit TCPV results forB0fK0 +0.07 -0.04 “sin2f1” = +0.06 0.33 0.09 A = +0.08 0.22 0.09 Poor tags (~1.9s @SM) (~0.9s @SM) Good tags Masashi Hazumi (KEK) FPCP2004

  9. History of “sin2f1” with fK0 _ sin2f1 from ccs “sin2f1” BABAR Belle 106 Masashi Hazumi (KEK) FPCP2004

  10. Checks: sin2f1 (B0J/y KS/L) [hep-ex/0409049] Validation of new data sample (SVD2) _ SVD1: 152M BB SVD1 S = 0.696  0.061 (stat) A = 0.011  0.043 (stat) Good tags _ SVD2: 123M BB SVD2 S = 0.629  0.069 (stat) A = 0.035  0.044 (stat) Good tags Dt (ps) f K0 4.5% (MC) SVD1: S = -0.68  0.46 A = -0.02  0.28 SVD2: S = +0.78  0.45 A =+0.17  0.33 many systematic checks, all ok  Masashi Hazumi (KEK) FPCP2004

  11. P _ sss penguin P’ _ sdd penguin T l2 l2 l4 l4 color-suppresed color-allowed T’ Other decay modes: B0g X0Ks • Ksgp+p- for all modes • Ksgp0p0 only by BABARfor hKs • not used for hgp+p-p0 • wKs only by Belle Masashi Hazumi (KEK) FPCP2004

  12. [hep-ex/0408076] [hep-ex/0409049] _ 227M BB _ 275M BB S = 0.73 fit (~0.9s @SM) Raw Asymmetry Good tags TCPV results forB0K+K-Ks (excluding fKs) “sin2f1” = +0.49 0.18 0.04 A = -0.08 0.12 0.07 +0.17 -0.00 “sin2f1” = +0.55 0.22 0.04 0.11 A = -0.10 0.14 0.06 f(CP=+1)=0.890.080.06 f(CP=+1)=1.030.150.05 Nsig = 39928 purity = 0.56 Nsig = 45228 (~0.7s @SM) Masashi Hazumi (KEK) FPCP2004

  13. [hep-ex/0408090] [hep-ex/0409049] “sin2f1” = +0.27 0.14 0.03 A = +0.21 0.10 0.03 _ 227M BB _ 275M BB S = 0.73 fit (~0.4s @SM) Raw Asymmetry Good tags TCPV results for B0ghKs “sin2f1” = +0.65 0.18 0.04 A = -0.19 0.11 0.05 Nsig = 51227 purity = 0.61 Nsig = 81938 (~3.1s @SM) Masashi Hazumi (KEK) FPCP2004

  14. [hep-ex/0408095] [hep-ex/0409049] “sin2f1” = +0.95 0.10 A = +0.24 0.31 0.15 _ 209M BB _ 275M BB S = 0.73 fit TCPV results for B0gf0(980)Ks +0.23 -0.32 “sin2f1” = -0.47 0.41 0.08 A = -0.39 0.27 0.08 Nsig = 9414 purity = 0.53 Nsig = 15219 Raw Asymmetry (~0.7s @SM) Good tags (~2.9s @SM) Masashi Hazumi (KEK) FPCP2004

  15. [hep-ex/0409049] _ 275M BB TCPV results for B0gwKs +0.13 -0.16 “sin2f1” = +0.75 0.64 A = +0.26 0.48 0.15 Nsig = 317 (7.3s) purity = 0.56 (~0.0s @SM) Raw Asymmetry Good tags Masashi Hazumi (KEK) FPCP2004

  16. p+ p- Ks trajectory B vertex IP profile g g Vertex reconstruction for B0gKsp0 Reconstruct B  Ksp0(g) vertex using Ks trajectory and boost trajectory or IP profile Sufficient resolution obtained Validated with J/y Ks (without using J/y) Good tags Masashi Hazumi (KEK) FPCP2004

  17. 7713 w/ vtx (high+low LR) [hep-ex/0408062] [hep-ex/0409049] “sin2f1” = +0.35 0.04 A = -0.06 0.18 0.06 _ 227M BB _ 275M BB S = 0.73 fit TCPV results for B0gKsp0 +0.30 -0.33 “sin2f1” = +0.30 0.59 0.11 A = -0.12 0.20 0.07 Nsig = 16816 purity = 0.55 low LR Nsig = 30023 (192 w/ vtx) * mmiss (not mES) high LR Nsig = 8318 purity = 0.17 (~0.7s @SM) Raw Asymmetry (~1.2s @SM) Good tags & high LR Masashi Hazumi (KEK) FPCP2004

  18. sin2f1 from bgs penguins at ICHEP04 sin2f1(bgsqq) = 0.43  0.08 sin2f1(bgccs) = 0.726  0.037 CL = 3.410-4 (3.6s) More decay modes are very welcome to elucidate the deviation Masashi Hazumi (KEK) FPCP2004

  19. TCPV in B0gP0Q0X0 T. Gershon and M. H., Phys. Lett. B 596 (2004) 163 • P0, Q0, X0 are CP-eigenstate spin-0 neutral particles. • J = 0 for B0  total angular momentum of the P0Q0X0 system should also be 0.  L’ = L. • CP(P0Q0X0) = CP(P0)CP(Q0)CP(X0)(-1)L+L’ = CP(P0)CP(Q0)CP(X0) • Therefore, P0Q0X0 is a CP eigenstate although it is a 3-body state ! P0 L’ B0 L X0 J=0 Q0 P0, Q0, X0 can be all different  large variety Masashi Hazumi (KEK) FPCP2004

  20. Masashi Hazumi (KEK) FPCP2004

  21. Masashi Hazumi (KEK) FPCP2004

  22. B0gKsKsKs (CP-even state) _ b _ s d _ d s _ s d Ks • No up quark in the final state  “pure” penguin • First observation by Belle (Nsig ~ 12 @ 78fb-1) • Rather clean signal • Room for improvement: Nsig can be larger • BaBar confirmed the signal with higher statistics at ICHEP04 (hep-ex/0408065) • Br = (6.5 0.8 0.8) x 10-6 B0 d Ks Ks Masashi Hazumi (KEK) FPCP2004

  23. (~2.8s @SM) “sin2f1” = -1.26 0.68 0.18 A = +0.54 0.34 0.08 New! Poor tags Good tags TCPV in B0gKsKsKs from Belle Masashi Hazumi (KEK) FPCP2004

  24. sin2f1(bgsqq) = 0.39  0.11 (Belle) 0.42  0.10 (BABAR) sin2f1(bgsqq)= 0.41  0.07 sin2f1(bgccs) = 0.726  0.037 sin2f1 from bgs penguins at FPCP04 WA World Average (WA) CL = 1.2 10-4 (3.8s) Masashi Hazumi (KEK) FPCP2004

  25. Ks track p+ p- g g B vertex IP profile g TCPV inradiative bgs penguins SM: g» polarized B0&B0 opposite |S| ≈ 2(ms/mb)sin 2f1 ≈ 3% A ~ 1% New Physics  Large S, A [e.g. Atwood,Gronau,Soni] * New phase not necessary; new amplitude that makes g “more flavor-nonspecific” is sufficient. B0  K*[Ksp0]g Analysis Technique: similar to B0 Ksp0 Masashi Hazumi (KEK) FPCP2004

  26. 275M BB - 124M BB B  K*[Ksp0]g TCPV [hep-ex/0409049] [hep-ex/0405082] Nsig=57 9 purity 0.65 S = 0 fit Good tags Nsig=105 14 S = +0.250.63 0.14 S = -0.79 0.09 A = +0.57 0.32 0.09 A fixed at zero 0.63 0.50 First step for new era of b  sg ! Masashi Hazumi (KEK) FPCP2004

  27. Generalized AGS (AGHS) D. Atwood, T. Gershon, M. H. and A. Soni, hep-ph/0410036 • Effective Hamiltonian • Decay amplitudes : F can be a state with more than one particle Masashi Hazumi (KEK) FPCP2004

  28. B0gKsp0g (1) • Decay amplitudes described with Dalitz variables (s1, z) • QCD respects both C and P, i.e. f(s1, z) remains the same. • Also • Thus Masashi Hazumi (KEK) FPCP2004

  29. B0gKsp0g (2) • TCPV for any angular momentum between Ks and p0 Cf. In the SM, S = -(2ms/mb)sin2f1 Masashi Hazumi (KEK) FPCP2004

  30. Revisiting B0gVg • TCPV formula V = C eigenvalue of V Masashi Hazumi (KEK) FPCP2004

  31. Cf. excluding K* mass region S= -0.39 (stat) A = +0.10 0.51 (stat) +0.63 -0.52 0.6 < M(Ksp0) < 0.8 or 1.0 < M(Ksp0) < 1.8GeV/c2 TCPV in B0gKsp0g (incl. K*gKsp0) from Belle Statistical errors reduced ! 0.6 < M(Ksp0) < 1.8GeV/c2 use all including K* region S= -0.58 0.11 A = +0.03 0.34 0.11 +0.46 -0.38 Poor tags New! Good tags Nsig = 10514 purity = 0.50 Masashi Hazumi (KEK) FPCP2004

  32. Summary • TCPV in hadronic bgs transitions • New results for B0gKsKsKs from Belle. • 3.8s deviation from the SM with all results combined. • More data, more modes are very welcome. • Important to know DSSM precisely if measured deviation is not so large (which is most likely) • TCPV in radiative bgs transitions • Generalized AGS oscillation • Cinternal determines the asymmetry, not CP • All P0Q0 states can be combined • New results for B0gKsp0g (incl. K*g) from Belle • Very promising approach to search for NP exp. 1034 1043 (Tony’s request) th. 10%  10 ppb (my request) Masashi Hazumi (KEK) FPCP2004

  33. Backup slides Masashi Hazumi (KEK) FPCP2004

  34. SM “tree pollution” • CKM-suppressed: O(l2) • OZI-suppressed: O(10-1) CP : CP eigenvalue of the final state;e.g. -1 for fKs S-CPsin2f1 A 0 if no new CPV phase TCPV in hadronic bgs penguins • BgfKs as a simple and clean example Dominant diagrams within the Standard Model (SM) similar diagrams for B0 + (C -A alsoused) Masashi Hazumi (KEK) FPCP2004

  35. TCPV in hadronic bgs penguins virtual particle (top quark, and more ?) CP violation “same” as J/Ks within the Standard Model (SM) Penguin~O(l2), Tree~O(l4) deviation = O(1)% Estimations of hadronic uncertainties Grossman, Isidori, Worah, PRD58, 057504 (1998) London, Soni, PLB407, 61 (1997) Grossman, Ligeti, Nir, Quinn, PRD68, 015004 (2003) Gronau, Grossman, Rosner, PLB579, 331 (2004) (not a complete list, sorry !) Penguin diagram Nice probe to search for new CP-violating phases Masashi Hazumi (KEK) FPCP2004

  36. S term with new physics phase • No guarantee that -2CP S < sin2f1 • Each decay mode has different “tree pollution within the SM”. • Large |A| may also be possible, but strong phase difference is not guaranteed. Masashi Hazumi (KEK) FPCP2004

  37. TCPV in hadronic bgs penguins • One of the most important topics in HEP now (and in the future) • e.g. SUSY GUT  “Atmospheric neutrinos can make beauty strange.” • Experimental techniques well established • Basics of TCPV measurements • Basics of rare B decay reconstruction and background reduction Masashi Hazumi (KEK) FPCP2004

  38. S = 0.73 fit B0→fK0 : CPV Result f K0 Good tags Poor tags Good tags 2003 Result fKS+fKL:S(fK0) = +0.06 0.33  0.09 A(fK0) = +0.08 0.22  0.09 ~2s away from SM Masashi Hazumi (KEK) FPCP2004

  39. SVD1/2 Data Checks combined fit SVD2 only SVD1 only Good tags Good tags SVD1: S = -0.68  0.46 A = -0.02  0.28 4.5% SVD2: S = +0.78  0.45 A =+0.17  0.33  many systematic checks, all ok Masashi Hazumi (KEK) FPCP2004

  40. Combined fit fKS/KL Results fKSonly fKL only -S =2.3 2.0 A = 0.6  1.2 S = 0.00  0.33 A = 0.06  0.22 Masashi Hazumi (KEK) FPCP2004

  41. B0f KS : Mass & Helicity f Helicity Mass bkg Masashi Hazumi (KEK) FPCP2004

  42. B0f K : Validations Control sample Lifetime fit w/ B fK/KS Asymmetry fit w/ fK B fKS B fK S(fK) = –0.030.20 A(fK) = +0.220.15 tB+= 1.67 tB0= 1.59 +0.12 –0.11 +0.20 –0.19 Masashi Hazumi (KEK) FPCP2004

  43. - History of b  sqq CPV Masashi Hazumi (KEK) FPCP2004

  44. B0K+K-KS : CP = 1 Mixture Since B0K+K-KS is 3-body decay, the final state is a mixture of CP = 1. How can we determine the mixing fraction? CP = 1 fraction is equal to that of l=even/odd CP = +1 CP = +1 K+ J=0 J=0 J=0 decay l B0 KS CP = (-1)l l K- J=0 Masashi Hazumi (KEK) FPCP2004

  45. B0K+K-KS : CP = 1 Mixture – cont’d • l-evenfraction in |K0K0> can be determined by |KSKS> system • Using isospin symmetry, CP = +1 l = even l = odd CP even Masashi Hazumi (KEK) FPCP2004

  46. Analysis of B0  K+K–KS (I) 227106B pairs Excluding  : dominant contribution (85%) of inclusive BR  much more statistics than KS • Unknown a prioriCP content: CP-even fraction must be determined experimentally • Angular moments analysis (main result): Study  [K+K–] helicity angle distribution and: Average moments computed from sum of background-corrected signal weights, returned by ML fit (“sPlot” technique [Pivk-Le Diberder, physics/0402083]) • Isospin analysis (cross check) [Belle, PRD 69, 012001 (2004)] (statistical error only) A. Höcker – sin2 in Loop-Dominated Decays with BABAR

  47. B0 K+K-Ks • Large branching fraction • color-allowed b g u may be a problem • Mixture of CP-even and CP-odd; determined experimentally. Masashi Hazumi (KEK) FPCP2004

  48. Available decay modes (P0 = Q0 only) Masashi Hazumi (KEK) FPCP2004

  49. f0(980)KS :p+p- Mass didtribution r fx Non-f0 components are determined from the M(p+p-) distribution [ f(f0KS) = 91% f(p+p-KS) = 2.3% f(r0KS) = 4.8% f(fxKS) = 1.6% Masashi Hazumi (KEK) FPCP2004

  50. Systematic errors on S KKKS: effective sin2f1 0.17 for CP-even fraction Masashi Hazumi (KEK) FPCP2004