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Matter-Antimatter Transformations at 3 Trillion Hertz

Matter-Antimatter Transformations at 3 Trillion Hertz. Prof. Joseph Kroll University of Pennsylvania Fall 2006. Executive Summary (1). At the beginning of ‘06 this is what was known. at least 3.5 cycles per lifetime. Executive Summary (2).

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Matter-Antimatter Transformations at 3 Trillion Hertz

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  1. Matter-Antimatter Transformations at3 Trillion Hertz Prof. Joseph Kroll University of Pennsylvania Fall 2006

  2. Executive Summary (1) At the beginning of ‘06 this is what was known at least 3.5 cycles per lifetime Joseph Kroll - University of Pennsylvania

  3. Executive Summary (2) Measure asymmetry A as a function of proper decay time t “unmixed”:particle decays as particle “mixed”:particle decays as antiparticle For a fixed value of ms, data should yield Amplitude “A” is 1, at the true value of ms Amplitude “A” is 0, otherwise Joseph Kroll - University of Pennsylvania

  4. Start 2006: Published Results on ms ms > 14.5 ps-1 95% CL Results from LEP, SLD, CDF I Amplitude method: H-G. Moser, A. Roussarie, NIM A384 p. 491 (1997) see http://www.slac.stanford.edu/xorg/hfag/osc/winter_2004/index.html Joseph Kroll - University of Pennsylvania

  5. March 2006: Result DØ Collaboration 1st reported direct experimental upper bound Probability “Signal” is random fluctuation is 5% 17 < ms < 21 ps-1 @ 90% CL V. M. Abazov et al., Phys. Rev. Lett. Vol. 97, 021802 (2006) Joseph Kroll - University of Pennsylvania

  6. April 2006: Result from the CDF Collaboration V. M. Abulencia et al., Phys. Rev. Lett. Vol. 97, 062003 (2006) Probability “Signal” is random fluctuation is 0.2% Under signal hypothesis: measure ms Joseph Kroll - University of Pennsylvania

  7. Outline • Neutral Weakly Decaying Mesons • Neutral Meson Matter-Antimatter Transformations • The Weak Interaction • History of Flavor Oscillations (Mixing) • B Physics at Hadron Colliders • Outline of the Measurement Strategy • Measuring B0s Oscillations at CDF • Results & Outlook Joseph Kroll - University of Pennsylvania

  8. Quarks and Hadrons Quarks: 3 Families Electric charge Three colors q q q Hadrons: colorless combinations of quarks Mesons: Baryons: Aside: other exotic combinations predicted: e.g., Pentaquarks Joseph Kroll - University of Pennsylvania

  9. Weakly Decaying Neutral Mesons Mass units: melectron = 0.511 MeV/c2, mproton = 0.938 GeV/c2 0.511 MeV/c2 = 9.11 £ 10-31 kg Joseph Kroll - University of Pennsylvania

  10. Neutral Meson Flavor Oscillations (Mixing) 1954: over 50 years ago Due to phase space suppression: K0L very long-lived: 5.2£ 10-8 s (K0S: 0.0090£ 10-8 s) Joseph Kroll - University of Pennsylvania

  11. Long-Lived Neutral Kaon Discovered by Ken Lande et al., (now at Penn) in 1956 Led to discovery of CP Violation in 1964 (Nobel Prize in 1980) BF(K0L!+-) = 0.2% Christenson, Cronin, Fitch, Turlay, Phys. Rev. Lett. 13, 138 (1964) Joseph Kroll - University of Pennsylvania

  12. Neutral Meson Mixing (Continued) Joseph Kroll - University of Pennsylvania

  13. Neutral B Meson Flavor Oscillations = 1/ = 1.6 psec Units: [m] = ~ ps-1. We use ~=1 and quote m in ps-1 To convert to eV multiply by 6.582£ 10-4 Joseph Kroll - University of Pennsylvania

  14. • • The Weak Interaction: Leptons Muon decay: Joseph Kroll - University of Pennsylvania

  15. • • • • Weak Interaction: Quarks & the Cabibbo Angle Pion Decay: Kaon Decay: Joseph Kroll - University of Pennsylvania

  16. The Cabibbo Angle:  = sinC Joseph Kroll - University of Pennsylvania

  17. texpoint test Joseph Kroll - University of Pennsylvania

  18. The Flavor Parameters (CKM Matrix) mass eigenstates ≠ weak eigen. related by Cabibbo-Kobayashi-Maskawa Matrix weak mass These fundamental parameters must be measured V is unitary: VyV = 1 Measurements + Unitarity assuming 3 generations Ranges are 90% CL PDG: S. Eidelman et al. Phys. Lett. B 592, 1 (2004) Joseph Kroll - University of Pennsylvania

  19. Wolfenstein Parametrization Illustrates Hierarchy 3 £ 3 complex unitary matrix: 3 real & 1 imag. parameters ≡ 3 angles, 1 phase Expand matrix in small parameter:  = Vus = sinCabibbo» 0.2 from hep-ph/0406184 Original reference: L. Wolfenstein, PRL, 51, p. 1945 (1983) Reference for this slide: A. Höcker et al., Eur. Phys. J. C21, p. 225 (2001); ibid, hep-ph/0406184 Joseph Kroll - University of Pennsylvania

  20. { } • B Meson Decay – Predominantly to Charm Semileptonic (not completely reconstructed – missing p) phase space factor } Hadronic Vcb = (41.3 § 1.5) £ 10-3 { } Small Vcb means Small  Long  (lifetime) • Joseph Kroll - University of Pennsylvania

  21. Small Vcb Means Long B Lifetime Nigel Lockyer (Penn), Bill Ford, Jim Jaros 2006 APS Panofsky Prize see also E. Fernandez et al. Phys. Rev. Lett. 51 1022 (1983) Long B lifetime  possible to see B0s particle-antiparticle transitions Joseph Kroll - University of Pennsylvania

  22. Neutral B Meson Flavor Oscillations Flavor oscillations occur through 2nd order weak interactions e.g. Same diagrams and formula for ms for Bs except replace “d” with “s” From measurement of md derive |V*tbVtd|2 All factors known well except “bag factor” £ “decay constant” md = 0.507 § 0.005 ps-1 (1%) (PDG 2006) from Lattice QCD calculations – see Okamoto, hep-lat/0510113 Joseph Kroll - University of Pennsylvania

  23. B Meson Flavor Oscillations (cont) If we measure ms then we would know the ratio ms/md Many theoretical quantities cancel in this ratio, we are left with Ratio measures |Vtd/Vts| This is why ms is high priority in Run II We know what to expect Using measured md & B masses, expected |Vts/Vtd| Predict ms» 18 ps-1 Joseph Kroll - University of Pennsylvania

  24. Why is this Interesting? Probe of New Physics e.g., W. Huo Eur. Phys. J. C 24 275 (2002) e.g., Harnik et al. Phys. Rev. D 69 094024 (2004) Supersymmetric particles 4th Generation Additional virtual particles increase ms Measured value can be used to restrict parameters in models Joseph Kroll - University of Pennsylvania

  25. Cross-section: [] = Area Luminosity: [L] = 1/Area 1/time Rate: [ L] = 1/time Number: ∫Ldt Integrated Lum. [∫Ldt] = 1/Area Collison rate: 2.5 MHz t quark production  = 6pb t quark rate @ 1032 cm-2s-1 = 0.6 mHz Tevatron Performance Key performance number is Integrated Luminosity Typical L = 1032 cm-2 s-1 ∫Ldt = 2 fb-1 Projected ∫Ldt = 4-8 fb-1 Barn: b = 10-24 cm2 pb = 10-36 cm2, pb-1 = 1036 cm-2 Joseph Kroll - University of Pennsylvania

  26. CDF II At the energy frontier at the Fermilab Tevatron (p-antip) TOF Detector (Penn Electronics) CDF rolls in to collision hall – Winter 2001 Installation of Silicon Tracking Device Fall 2000 Penn COT Electronics Joseph Kroll - University of Pennsylvania

  27. Experimental Steps for Measuring Bs Mixing 1. Extract B0s signal – decay mode must identify b-flavor at decay (TTT) Examples: 2. Measure decay time (t) in B rest frame (L = distance travelled) (L00) 3. Determine b-flavor at production “flavor tagging” (TOF) “unmixed” means production and decay flavor are the same “mixed” means flavor at production opposite flavor at decay Flavor tag quantified by dilution D = 1 – 2w, w = mistag probability Joseph Kroll - University of Pennsylvania

  28. Schematic Joseph Kroll - University of Pennsylvania

  29. Event Display Joseph Kroll - University of Pennsylvania

  30. Measuring Bs Mixing (cont.) 4. Measure asymmetry Asymmetry is conceptual: actually perform likelihood fit to expected “unmixed” and “mixed” distributions these formulas assume perfect resolution for t Joseph Kroll - University of Pennsylvania

  31. Measurement of Oscillation “Right Sign” “Wrong Sign” What about experimental issues? Joseph Kroll - University of Pennsylvania

  32. Realistic Effects flavor tagging power, background displacement resolution momentum resolution (L) ~ 50 m mis-tag rate 40% (p)/p = 5% Joseph Kroll - University of Pennsylvania

  33. All Effects Together Joseph Kroll - University of Pennsylvania

  34. 1st Evidence: Time Integrated Mixing:  1987 is the time integrated mixing probability In principle, a measurement of  determines m - 1st Bd mixing measurements were  measurements - d = 0.187 § 0.003 (PDG 2004) - this does not work for Bs: s = 0.5 (the limit as x!1) Inclusive measurements at hadron colliders yield Joseph Kroll - University of Pennsylvania

  35. Discovery of Neutral B Flavor Oscillations UA1 1987: Evidence for B0 & B0s mixing Followed up by observation of B0 mixing by ARGUS: H. Albrecht et al., (25 June 87) Phys. Lett. B 192, 245 (1987) Implications: mtop>50 GeV/c2 Top quark is heavier than expected Ellis, Hagelin, Rudaz, Phys. Lett. B 192, 201 (1987) Joseph Kroll - University of Pennsylvania

  36. State of the Art Measurement of md B. Aubert et al. Phys. Rev. Lett. 88, 221802 (2002) Joseph Kroll - University of Pennsylvania

  37. Measuring ms at CDF: Signal Decay sequence Four charged particles in final state: K+ K-+- Complete reconstruction: pB negligable Joseph Kroll - University of Pennsylvania

  38. Decay position production vertex 25 m £ 25  m Decay time in B rest frame Lifetime Measurement Joseph Kroll - University of Pennsylvania

  39. <t> = 86 £ 10-15 s ¼ period for ms = 18 ps-1 Oscillation period for ms = 18 ps-1 Decay Time Resolution Maximize sensitivity: use candidate specific decay time resolution Superior decay time resolution gives CDF sensitivity at much larger values of ms than previous experiments Joseph Kroll - University of Pennsylvania

  40. B Flavor Tagging We quantify performance with efficiency and dilution D = fraction of signal with flavor tag D = 1-2w, w = probability that tag is incorrect (mistag) Statistical error A on asymmetry A (N is number of signal) statistical error scales with D2 Joseph Kroll - University of Pennsylvania

  41. Based on correlation between charge of fragmentation particle and flavor of b in B meson Same Side Flavor Tags TOF Critical (dE/dx too) Both due to PENN Joseph Kroll - University of Pennsylvania

  42. Time of Flight Detector (TOF) Kaon ID for B physics • 216 Scintillator bars, 2.8 m long, 4 £ 4 cm2 • located @ R=140 cm • read out both ends with fine mesh PMT • (operates in 1.4 T B field – gain down ~ 400) • anticipated resolution TOF=100 ps • (limited by photostatistics) Measured quantities: s = distance travelled t = time of flight p = momentum Derived quantities: v = s/t m = p/v Joseph Kroll - University of Pennsylvania

  43. Chunhui Chen now PD at Maryland Recent Penn CDF group Ph. D.s Successfully defends thesis on Charm meson production cross-sections: First PRL from Tevatron Run II Designed & built electronics for CDF TOF Joseph Kroll - University of Pennsylvania

  44. Denys Usynin: Now at JP Morgan Recent Penn CDF Group Ph. D.s Contributions to several TOF electronic components & PMT assembly Used TOF to measure types of particles produced in association with B mesons. First such results from hadron collider Crucial for B0s oscillations Joseph Kroll - University of Pennsylvania

  45. Kaons Produced in Vicinity of B’s Larger fraction of Kaons near B0s compared to B0, B+, as expected Ph. D. Thesis, Denys Usynin Joseph Kroll - University of Pennsylvania

  46. Contributions to CDF Trigger Trigger selects in real time interesting collisions Crucial for successful physics program Fritz Stabenau spent one year with us working on 2nd Level upgrade Kristian Hahn made major contributions to 2nd Level upgrade Joseph Kroll - University of Pennsylvania

  47. Flavor Tagging Summary Opposite-side tags: D2 = 1.5% Penn played the lead role in Run I CDF analysis to develop these tags: Ph. D. Thesis, Owen Long Same-side kaon tag: D2 = 4.0% Penn played the lead role in proposing and building TOF Measured kaons near B’s: Ph. D. Thesis, Denys Usynin Same-side kaon tag increases effective statistics £ 4 Joseph Kroll - University of Pennsylvania

  48. Results: Amplitude Scan Sensitivity 25.3 ps-1 A/A = 3.5 Joseph Kroll - University of Pennsylvania

  49. Results: Amplitude Scan Sensitivity 31.3 ps-1 A/A = 6.1 Joseph Kroll - University of Pennsylvania

  50. Measured Value of ms Hypothesis of A=1 compared to A=0 - log(Likelihood) Joseph Kroll - University of Pennsylvania

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