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Exploring CP Violation and Rare B Decays at B-Factories: Physics Reach and Luminosity

Discover the physics reach at B-factories, measuring time-dependent CP violations and rare B decays. Learn about CKM suppressed decays, radiative penguins, and new physics signatures in the Unitarity Triangle. Explore the potential for New Physics reshaping and the impact on Charm, Tau, and Lepton decays. Witness the record luminosity and future upgrades of B-factories, offering unique tools for experimental measurements and collider advancements.

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Exploring CP Violation and Rare B Decays at B-Factories: Physics Reach and Luminosity

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  1. B-Factories: Physics Reach Luminosity CPV and CKM Rare B decays Conclusions Livio Lanceri – Univ. and INFN Trieste INFN-CSNI – LNF, February 4, 2003

  2. Discovery potential at the B factories • CKM and Unitarity Triangle • SM predicts a pattern of CPV, from phase in the CKM matrix • B factories can measure both angles and sides of the Unitarity Triangle • New phases from New Physics may reshape the UT • Rare B Decays • CKM suppressed (tree b  u), Radiative Penguins (QCD, EM, EW), leptonic B decays • Common feature (Penguins, leptonic): New Physics signatures from rates and asymmetries (new virtual particles in the loops) • Charm, tau • Examples: D mixing and lepton number violating  decays • Very small in SM  windows for New Physics L.Lanceri - B-Factories: Physics Reach - CSNI

  3. Inclusive tag (lepton, K, …): tag(1-2w)2 28% (Exclusive tag: tag  0.10.2%) z(CP) z(tag) rec  1540% < z >  260 m z (RMS) 190 m Experimental ingredients Asymmetric B factories optimized for measurements of time-dependent CP violating asymmetries OK also for other measurements (rare B decays, …) Open trigger! No B physics losses at trigger level High efficiencies, small bkgd Unique tool at B factories: exclusive B tagging with fully rec. B (“single B beam”) Luminosity is a key factor L.Lanceri - B-Factories: Physics Reach - CSNI

  4. BABAR/PEP-II Record peak luminosity: 4.6 x 1033cm-2s-1(~5 BB/s) max lumi/24h: 303 pb-1 total recorded lumi to date: ~0.1 ab-1 (~10% off-peak) Restarted end Nov.2002 after 4 months shutdown (Forward IFR upgrade) Belle/KEK-B Record peak luminosity: 8.2 x 1033cm-2s-1(~8 BB/s) max lumi/24h: 433 pb-1 total recorded lumi to date: ~0.1 ab-1 (~10% off-peak) Restarted in January 2003 after vacuum loss forced stop in December B-Factories: experiments and luminosity • c.f. integrated luminosity for • Argus (1983-1987): ~100 pb-1 • CLEO (1981-2000): ~16 fb-1 L.Lanceri - B-Factories: Physics Reach - CSNI

  5. PEP-II without upgrades 1.1 ab-1 1.6 x 1034 peak integrated 0.5 ab-1 2006 2009 L.Lanceri - B-Factories: Physics Reach - CSNI

  6. NO (Super-KEKB?) Minimal upgrade Feasible from 2005 Shut-down  3 months 0.40.5 ab-1/year Limited cost SuperPEP/SuperBaBar Year 20...? New collider, (and new detector…) Snowmass: 370M$ 2ab-1 in 2009 PEP-II upgrade scenarios From J.Seeman/SLAC L.Lanceri - B-Factories: Physics Reach - CSNI

  7. Path to higher PEP-II luminosity Luminosity4.6E331E342E344E34Units I+ 1800 2700 3600 4500 mA I- 950 1400 1760 2000 mA Beta y* 11.5 9 7 4.5 mm Beta x* 50 50 50 50 cm Bunch Length 1.3 1.0 0.8 0.5 cm # bunches 792 1300 1500 1600 Vert. Emitt. 2.5 1.4 1.1 0.7 nm Horiz. Emittance 40/50 30/45 32/47 40/48 nm (+/-) Crossing angle 0 0 0 ~+/-8 mrad Tune shifts (x/y) 7.5/4.5 8.0/5.7 8.2/6.0 8.4/6.3 x100 Number RF stations 7 10 13 15 Date hardware ready Jan 02 Dec 02 Dec 04 Nov 05 Date for luminosity Jun 02 July 03 Dec 05 Dec 06 (J.Seeman, BaBar Collaboration meeting, Sept.2002) L.Lanceri - B-Factories: Physics Reach - CSNI

  8. BaBar Long Term Planning TF For the 4x1034 PEP-II upgrade: We studied the physics reach in some channels for: 0.5 ab-1 (2006), 2.0 ab-1 (end of the decade) And: Interest/need of an accompanying BaBar detector upgrade ? (Conclusion: only Barrel IFR) Most extrapolations reported here come from the preliminary report of the TF L.Lanceri - B-Factories: Physics Reach - CSNI

  9. What about KEK-B/Belle upgrades ? EoI (January 2002): Super KEK-B, L = 1035cm-2s-1 - LER: e- , I = 10A; HER: e+, I = 3A Linac upgrade (e-  e+) - Vacuum system (ante chambers); RF system (52 cavities, 12SC) - 15 mrad crossing, final focussing Total cost (KEK-B + Belle):  400 M$ EoI preliminary plan: Present plans: … ?? Workshop at KEK, Feb.2003 L.Lanceri - B-Factories: Physics Reach - CSNI

  10. CPV and CKM: phases sin2 sin2 

  11. CP eigenvalue Amplitude ratio B0fcp/B0fcp B mixing CP asymmetry: Time Dependence CPV in mixing-decay interference direct CPV dN exp(–|Dt|/tB) ( 1 ± D (Ssin(DmDt)-Ccos(DmDt)) )  R Flavour tag D mis-tag dilution R time resolution Measured from data (Flavour sample)! L.Lanceri - B-Factories: Physics Reach - CSNI

  12. BaBar, sin2b: results Charmonium modes on-peak: 81.9 fb-1 off-peak: 9.6 fb-1  89 M BB pairs sin2b = 0.755  0.074 sin2b = 0.723  0.158 sin2b = 0.741  0.067  0.034 tagged CP sample: 2631 flavor sample: 25375 Modes with Penguins Yield (pure Penguin!) in Standard Model L.Lanceri - B-Factories: Physics Reach - CSNI

  13. decays with charmonium: Source dsin2b CP and Mix BG DCS decays, tag side 0.017 0.008 Klong BG 0.015 Dt meas. and RF 0.017 Signal Dilutions 0.012 Fit bias correction 0.010 B lifetime 0.004 Dmd 0.003 Total 0.034 BaBar, sin2b: systematics Asymptotic 0.004 0.008 0.003 0.010 0.010 0.003 0.003 0.003 0.018 Using only lepton tags: 0.01 L.Lanceri - B-Factories: Physics Reach - CSNI

  14. sin2b: projected errors (BaBar) • Extrapolated statistical and systematic uncertainties Statistical uncertainty For “golden” modes only L.Lanceri - B-Factories: Physics Reach - CSNI

  15. u b t d p- p- u d B0 B0 b u u p+ d d p+ d d Mixing + T: b+g P: -b,d sin2eff fromB0+- Observables in +- CP asymmetry (time-dependent) Extra weak phase –b, strong phase d, and |P/T|, modify a by k • : from isospin analysis L.Lanceri - B-Factories: Physics Reach - CSNI

  16. BABAR Belle 2 Belle 1 BaBar and Belle: Spp and Cpp With incomplete information (no isospin analysis): • Measure Spp and Cpp from both sinDmDt and cosDmDt terms . • Compare with predicted Spp and Cpp values for given a, b, |P/T|, and d. Assume for instance: cf. Gronau and Rosner, Phys. Rev. D65, 093012 (2002) L.Lanceri - B-Factories: Physics Reach - CSNI

  17. Results and extrapolations forsin2eff Results (0.08 ab-1) Extrapolated errors (BaBar) L.Lanceri - B-Factories: Physics Reach - CSNI

  18. sin2: isospin analysis (Gronau & London) Need flavor tagged rates for +-, 0, 00 BaBar: L.Lanceri - B-Factories: Physics Reach - CSNI

  19. Grossman-Quinn bound: BaBar, extrapolations: vs BF(00), at fixed Luminosity Upper bounds on = 2eff-2 BaBar, present data: Small gain with lumi Most powerful at small BF L.Lanceri - B-Factories: Physics Reach - CSNI

  20. BR(B`gp`p0) = 4.1x10-6 BR(B0gp+ p-) = BR(B0gp+ p-) = 4.7x10-6 Isospin analysis: projections - 1 • Sensitivity to : toy MC with BaBar detector • Assumptions (example): NB: 4-fold ambiguity ! <BR(Bgp0p0)> = 2.0x10-6 L = 0.5 ab-1 L = 2.0 ab-1   L.Lanceri - B-Factories: Physics Reach - CSNI

  21. Isospin analysis: projections - 2 • BaBar sensitivity on : summary • (4-fold ambiguity not included) • Assumptions: • 00 reconstruction efficiency: rec = 0.18 • For each B tagging category: • Tagging performance , D = 1-2w • Bkgd effective cross sect. B (106) L.Lanceri - B-Factories: Physics Reach - CSNI

  22. Quasi-2-body B0  analysis hep-ex/0207068 Acp 81.9 fb-1 L.Lanceri - B-Factories: Physics Reach - CSNI

  23. B0+– - B0–+ Interference Region B0+– - B000 Interference Region 3-body (+-0) Dalitz analysis for  • 11 parameters (“fundamental”): • remove overall phase & normalization: 9 parameters Suffers from mirror solutions • 10 parameters (“amplitudes”): • remove overall phase & normalization: 8 parameters • obtain fundamental parameters from subsequent fit. No mirror solutions. Does not depend on particular weak phase decomposition …work in progress L.Lanceri - B-Factories: Physics Reach - CSNI

  24.  at the B factories • sin(2) from fully/partially reconstructed B  D(*) • Analysis in progress • Rates and asymmetries in B   K, KK • Require theoretical assumptions • Promising developments: 3-body decays, Dalitz analysis (work in progress) • B  D(*)K(*), D(*)Ks, DKs, D(*)K(*), … • Most advanced analysis in BaBar: B-gD0(CP)K- • Sensitivity extrapolations from preliminary results 81.2 fb-1 L.Lanceri - B-Factories: Physics Reach - CSNI

  25. g (Gronau-London-Wyler)  from B-gD0(CP)K- Observables: n1, p1, n2, p2 Theor. parameters: , r,  L.Lanceri - B-Factories: Physics Reach - CSNI

  26.  from B-gD0(CP)K-: projections Recent experimental results (BaBar) Toy MC projections: (Fit unreliable for r = 0.1) r=0.3 (0.5 ab-1), sin2g = 0.75  fit: sin2g = 0.720.23, g = (59.910.2)o r=0.2 (2ab-1), sin2g = 0.75  fit: sin2g = 0.710.14, g = (58.57.4)o r=0.2 g=60o Dd=30o (2ab-1) ACP=0.174 0.031 L.Lanceri - B-Factories: Physics Reach - CSNI

  27. Vcb (Vub) (u) |Vtd/Vts|2 (,…) CKM Triangle: sides

  28. Breco Brecoil D(*) Y(4S) l p n |Vub| from fully tagged SL decays Semileptonic decays on the recoil of fully rec. B (~1KB0 /fb-1, ~2KBch. /fb-1) To separate bul MX(< MD) ( ~ 60-80%) (or other variables: P*l, q2) Xu L.Lanceri - B-Factories: Physics Reach - CSNI

  29. projected errors for|Vub| Selection: One B reconstructed in D(*)X Lepton momentum and neutrino mass Kaon veto, charge balance Fit Mx with constraints MX distribution fit: buln, bcln, background Errors: Statistical L(ab-1) = 0.08 0.5 2.0 10 sstat(%) = 7.0 2.8 1.4 0.6 Experim. Systematic ~5% (now)  2.5% (bcln bkgd) Theoretical ~ 9% (s(mb)=90MeV)  5% (buln above cut) Mx cut, b quark Fermi motion from b  s, Mx bins Further improvements from lattice QCD, restricted phase space Mx (GeV) L.Lanceri - B-Factories: Physics Reach - CSNI

  30. Towards Vtd/Vts Extrapolation 0.5 ab-1 2 ab-1 From experience gained with present data 0.5 ab-1 2 ab-1 Significant gain if one can reduce the background by factor 2 10% error due to long range effects to be compared to 6% for Dmd/Dms L.Lanceri - B-Factories: Physics Reach - CSNI

  31. QCD penguin bu tree EM penguin Rare B decays EW penguin leptonic

  32. Charmless decays: Direct CP violation? Time-integrated CP asymmetries: No evidence for direct CPV yet Theoretical expectations: Tree + Penguin: ACP 10% Pure Penguin: ACP 1% Present sensitivity (most channels) statACP 10% systACP 12% Charge asym. L.Lanceri - B-Factories: Physics Reach - CSNI

  33. Signal Box Sideband m(D0)Rec-m(D0)PDG (m(D0)) Remaining neutral Energy (GeV) EW Penguins (BaBar): Exclusive measurements: 85M BB pairs Inclusive (bsl+l-) in progress Preliminary Theory (SM): B(B+K+)  3.8 x 10-6 56M BB pairs, fully reco. SL tag 2 events observed (2.2 bkgd expected) B(B+K+)  9.410-5 (90% CL) L.Lanceri - B-Factories: Physics Reach - CSNI

  34. Leptonic decays (BaBar) • Already published, to be updated (Run1+2) • BF(B ) < 1.7 10-6 (90% CL); int.lumi. 19.4 fb-1 • ICHEP 2002 (Run1+2): • BF(B  e+e-) < 3.3 10-7 , BF(B  +-) < 2.0 10-7 , • BF(B  +e-) < 2.1 10-7 (90% CL) • New analyses on B+ + (Run1+2),with: • Lepton tag or Fully reconstructed hadronic tag • Sensitivity competitive with existing exptal limits (LEP: 5.7  10-4) L.Lanceri - B-Factories: Physics Reach - CSNI

  35. Some extrapolated yields (BaBar) • Extrapolated yields for B+ + andB+K+ Present analysis: backgrounds:  280 events in 80fb-1 K 2 events in 56MBB pairs L.Lanceri - B-Factories: Physics Reach - CSNI

  36. Rare decays - Summary Projections from Snowmass 2001: reconstructed events Efficiencies from BaBar/Belle; some numbers should be updated (*) “B exclusive tag” (assuming   0.2%) Asymmetries! Rates… L.Lanceri - B-Factories: Physics Reach - CSNI

  37. Conclusions & Outlook • B factories discovered CP violation in B decays and are measuring sin2 with increasing accuracy • Each of the two B factories integrated a luminosity of about 0.1ab-1 and should integrate 0.5ab-1 by 2006; depending on the machine upgrade options, about 2ab-1 per experiment could be within reach by the end of the decade • Such an increase in integrated luminosity will significantly extend the physics reach of the B factories, both for the Unitarity Triangle, and for rare B decays • Other topics, including charm and tau physics, are part of the physics program (see backup slides) L.Lanceri - B-Factories: Physics Reach - CSNI

  38. Backup slides

  39. “short distance”  x Vcd,cs W- Vud,us c u D0 d,s d,s D0 u c V*ud,us W+ V*cd,cs “long distance”  -iy K-, D0 D0 K+,+ Charm An example: D mixing Very small in the S.M. • 2  additional suppression  A window for new physics Sensitivity estimate (BaBar) 1, including statistical and systematic uncertainties L.Lanceri - B-Factories: Physics Reach - CSNI

  40. lepton number is violated in many extensions of the S.M. (present limits, O(10-6) are close to some model predictions) tau Another example: lepton number violation S.M., extended to include n mixing and mass: BR(t) ~O(10 - 34) BaBar sensitivity, projections: L.Lanceri - B-Factories: Physics Reach - CSNI

  41. B physics: accelerators Hadron colliders: Higher cross sctions, but: higher bkgd, lower efficiency B-factories: Luminosity is the critical factor L.Lanceri - B-Factories: Physics Reach - CSNI

  42. BaBar Detector EMC 6580 CsI(Tl) crystals e+ (3.1GeV) 1.5T solenoid DIRC (PID) 144 quartz bars 11000 PMs Drift Chamber 40 stereo layers e- (9GeV) Silicon Vertex Tracker 5 layers, double sided strips Instrumented Flux Return iron / RPCs (muon / neutral hadrons) • SVT: B vertex z resolution ~70 microns • Tracking: (pT)/pT= 0.13%  pT0.45% • DIRC: K- separation > 3.4 for P < 3.5GeV/c • EMC: E/E = 1.33%E-1/4 2.1% L.Lanceri - B-Factories: Physics Reach - CSNI

  43. CP asymmetries: sensitivity • Error on the diluted CP asymmetries (Aobs= DACP) • Number of events: • Efficiencies: • Dilutions: • B factories • Small cross section: • higher efficiencies and better dilutions   D2 L.Lanceri - B-Factories: Physics Reach - CSNI

  44. Bflav Mixing sample BaBar, sin2b: “golden” modes, now CP states with charmonium: to measure sin2 2641 tagged events on-peak: 81.9 fb-1 off-peak: 9.6 fb-1  89 M BB pairs c1 Ks J/Y Ks (Ks p+p-) Flavor states: to measure mixing and D, R J/Y Ks (Ksp0p0) 25375 events Y(2s) Ks J/Y K*0 (K*0  Ksp0) J/Y KL hcp=+1 L.Lanceri - B-Factories: Physics Reach - CSNI

  45. CP violation: sin2 sin2b = 0.741  0.067 (stat)  0.034 (syst) hcp=-1 hcp=+1 sin2b = 0.755  0.074 sin2b = 0.723  0.158 PRL 89 (2002) 201802 L.Lanceri - B-Factories: Physics Reach - CSNI

  46. sin2 - K0S hep-ex/0207070 • Pure QCD Penguin, sensitive to New Physics contributions • In the SM, time-dependent asymmetry in K0S measures sin2b B  K0S 51 events From 87 M B pairs: L.Lanceri - B-Factories: Physics Reach - CSNI

  47. If no penguins: we measure -sin2b + 407 events sin2 - J/0 hep-ex/0207058 L.Lanceri - B-Factories: Physics Reach - CSNI

  48. sin2 - ’K0S B  ’K0S 203 events Large Penguin contribution expected ! preliminary L.Lanceri - B-Factories: Physics Reach - CSNI

  49. sin2 - D*D* (bccd) hep-ex/0207072 • D*+D*-, is not a CP eigenstate (L=0,2 and L=1) • CP odd fraction R  • .Transversity analysis B0D*+ D*- CP-odd fraction R = 0.07  0.06  0.03  mostly CP-even ! L.Lanceri - B-Factories: Physics Reach - CSNI

  50. + • We measure : • Im(l+) • |l+| -sin2b Small ( < 0.1 T) penguin contribution expected Im(l+) = 0.31  0.43 (stat)  0.13 (syst) -sin2b = -0.741  0.067 |l+| = 0.98  0.25 (stat)  0.09 (syst) From 126  12signal events sin2 - D*D* preliminary L.Lanceri - B-Factories: Physics Reach - CSNI

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