1 / 69

Low Energy Tests of the Standard Model

Low Energy Tests of the Standard Model. * PAST. * PRESENT. * FUTURE. Emlyn Hughes Spin 2004 Trieste October 14, 2004. Electroweak Mixing Angle. e = g sin q w. Characterizes the mixing between the weak and EM interaction in the electroweak theory. 2. M w. 2. sin 2 q w = 1 -. M z.

britain
Download Presentation

Low Energy Tests of the Standard Model

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Low Energy Tests of the Standard Model * PAST * PRESENT * FUTURE Emlyn Hughes Spin 2004 Trieste October 14, 2004

  2. Electroweak Mixing Angle e = g sinqw Characterizes the mixing between the weak and EM interaction in the electroweak theory 2 Mw 2 sin2qw = 1 - Mz

  3. 3 Types of Measurements * Electron scattering (parity violation) * Atomic parity violation * Neutrino physics (NC/CC cross section)

  4. Parity Violation in Polarized Electron Scattering e- e- e- e- g Z unpolarized quarks or electrons or protons Parity conserving Parity violating

  5. Parity Violation in the Electroweak Theory R L s - s APV = R L s + s g2 2 + q2 AW mZ 2AW AEM PV 2 ~ 2 ~ ~ A AEM 2 2 + e2 AW AEM q2 PV q2 A ~ 2 2 mZ

  6. SLAC

  7. End Station A End Station A

  8. SLAC Parity Experiments Detector e- Target High Energy (unpolarized) R L s - s APV = Parity-violating asymmetry R L s + s

  9. SLAC E80

  10. Yale E80 Polarized Source

  11. SLAC End Station A

  12. SLAC E95

  13. Results on Parity Violation E80 ALR < 5 x 10-3at Q2 ~ 1.4, 2.7 GeV2 E95 ALR < 3.2 x 10-3at Q2 ~ 4 GeV2 Not sensitive to electroweak mixing in the Standard Model

  14. First Measurements of Electroweak Mixing

  15. SLAC E122

  16. SLAC E122 Detector e 16 – 22 GeV Liquid Deuterium GaAs source High current 30 cm target Dedicated run

  17. 120 Hz Reversed every few runs

  18. SLAC E122 waveplate reversal

  19. SLAC E122 waveplate reversal Parity-violating asymmetry

  20. SLAC E122 Energy Scan Parity-violating asymmetry

  21. SLAC E122 Result (1978) sin2qw = 0.224 + 0.020 First definitive measurement of mixing between the weak and electromagnetic interaction

  22. Atomic Parity Violation e- e- g or Z p 2 2 mea LR q2 -14 A ~ 2 ~ 2 10 ~ 2 2 mZ mZ

  23. Experiment Z3 Law Heavy Atoms Theory PV Signal sin2qw Bismuth Z = 83

  24. Atomic Parity Violation Bismuth

  25. Atomic Parity Violation Bismuth

  26. Atomic Parity Violation Bismuth

  27. Atomic Parity Violation Bismuth E122

  28. Neutrino Physics Bubble Chamber Gargamelle

  29. HPWF Neutrino Detector (Harvard, Pennsylvania, Wisconsin, Fermilab)

  30. 1974

  31. 1978

  32. (1977) (1977) (1975) (1977) 1978

  33. TODAY... LEP and SLC e+e- collider Dsin2qw = 0.00016 (PDG2004) from Z pole measurements

  34. Status in 1999 sin2qw ~5% Q (GeV)

  35. SLAC Experiment E158 Detector e 50 GeV Liquid Hydrogen e-e- scattering s - s APV = s + s Without electroweak radiative corrections, 2 m E GF 16 sin q 1 ( ) - sin2qw APV = 2 4 2p  (3 + cos q)2 In practice: APV ~ 1.5 x 10-7

  36. E158 Collaboration • SLAC • Smith College • Syracuse • UMass • Virginia • UC Berkeley • Caltech • Jefferson Lab • Princeton • Saclay 7 Ph.D. Students 60 physicists Sept 97: EPAC approval 1998-99: Design and Beam Tests 2000: Funding and construction 2001: Engineering run 2002: Physics Runs 1 (Spring), 2 (Fall) 2003: Physics Run 3 (Summer)

  37. Scattering Processes e- e- e- e- g Z e- e- e- e- Parity-conserving Parity-violating e- e- g g Background p p

  38. Challenges I. Statistics II. Beam monitoring & resolution  jitter vs. statistics III. Beam systematics  false asymmetries IV. Backgrounds

  39. target Detector cart Concrete shielding Spectrometer magnets Setup in End Station A

  40. STATISTICS # electrons per pulse 107 Rep rate (120 Hz) 109 Seconds/day 1014 100 days 1016 DA ~ 10-8

  41. II. BEAM MONITORING

  42. toroid 30 ppm energy 1 MeV BPM 2 microns Agreement (MeV) BPM24 X (MeV) Resolution 1.05 MeV BPM12 X (MeV) Beam Monitoring Correlations

  43. III. Beam Asymmetries Polarized source

  44. SLOW REVERSALS * Halfwaveplate @ source ~few hours * 48 vs. 45 GeV energy ~ few days

  45. APV vs. time ppb

  46. Asymmetry Results

More Related