1. Parity Violation in Electron Scattering Emlyn Hughes SLAC DOE Review June 2, 2004 *SLAC E122 *SLAC E158 *FUTURE

2. Polarized Electron Scattering e-   unpolarized quarks or electrons or protons Parity conserving Parity violating

3. Electroweak Mixing Angle e = g sin  w Characterizes the mixing between the weak and EM interaction in the electroweak theory sin 2  w = 1 - MwMw MzMz 2 2

4. SLAC Parity Experiments e- Target (unpolarized) High Energy Detector A PV =  -   +  Parity-violating asymmetry RL RL

5. End Station A

6. SLAC E122

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

8. Reversed every few runs 120 Hz

9. SLAC E122 waveplate reversal

10. Parity-violating asymmetry SLAC E122 waveplate reversal

11. SLAC E122 Energy Scan Parity-violating asymmetry

12. SLAC E122 Result sin 2  w = 0.224 + 0.020 First definitive measurement of mixing between the weak and electromagnetic interaction (1978)

13. Atomic Parity Violation Bismuth

14. Atomic Parity Violation Bismuth

15. Atomic Parity Violation Bismuth

16. Atomic Parity Violation Bismuth E122

17. LEP and SLC e + e - collider  sin 2  w = 0.00017 (PDG2002)from Z pole measurements TODAY...

18. Q (GeV) sin 2  w Status in 1999 ~5%

19. SLAC Experiment E158 Detector e 50 GeV Liquid Hydrogen A PV =  -   +  Without electroweak radiative corrections, In practice: A PV ~1.5 x 10 -7 2  (3 + cos  ) 2 2 16 sin  2 A PV = 1 4  sin 2  w () m E G F e-e- scattering

20. UC Berkeley Caltech Jefferson Lab Princeton Saclay SLAC Smith College Syracuse UMass Virginia 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) E158 Collaboration

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

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

25. STATISTICS # electrons per pulse10 7 Rep rate (120 Hz)10 9 Seconds/day10 14 100 days10 16  A ~ 10 -8

26. II. BEAM MONITORING

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

29. III. Beam Asymmetries Polarized source

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

31. A PV vs. time ppb

32. IV. BACKGROUNDS *electron-proton elastic scattering *pion production *radiative inelastic electron-proton scattering W 2 > 3 GeV 2 *2 photon events with transverse polarization ******

33. ep Detector Asymmetry

34. Transversely Polarized Beam

35. Run 1: Spring 2002 Run 2: Fall 2002 Run 3: Summer 2003 E158 Physics Runs

36. Run I & II

37. Run I

38. A PV =  175  30 (stat)  20 (syst) ppb sin 2  = 0.2293 ± 0.0024 (stat) ±0.0016 (syst) At Q 2 = 0.027 (GeV/c) 2 …. w RUN I FINAL RESULT MS sin 2  = 0.2311 ± 0.00016 w MS Theory:

39. A PV =  160  21 (stat)  17 (syst) ppb sin 2  = 0.2308 ± 0.0015 (stat) ±0.0014 (syst) At Q 2 = 0.027 (GeV/c) 2 …. w RUN I & II PRELIMINARY MS sin 2  = 0.2311 ± 0.00016 w MS Theory:

40. Q (GeV) sin 2  w Status in 1999

42. 0.240 0.238 0.236 0.234 0.232 0.230 1997 1998 1999 2000 Standard Model Cesium Atomic Parity Violation Result vs. Time sin 2  w (Colorado measurement) Modifications in the theoretical corrections to the atomic structure Wieman et al. Bennett Wieman Derevianko Dzuba Flambaum 20012002 Kozlov Porsev Tupitsyn Johnson Bednyhakov Soff Kuchiev Flambaum 2003

43. Q (GeV) sin 2  w Status today Run I & II

44. sin 2  w Q (GeV) Including E158 projections... Run I & II E158 Projected Error bar

45. Beyond Standard Model Implications... *Limit on  LL ~ 7 TeV *Limit on Z  ~ 400 GeV *Limit on lepton flavor violating coupling ~ 0.02G F  Limits will improve with new data

46. Future Measurements

47. LHC Not a parity experiment …  Has major impact on precision low energy tests for discovery potential Z’, supersymmetry, compositeness, leptoquarks, etc… in the TeV range

48. SUMMARY *Performed a first measurement of parity violation in e - e - scattering *Future parity experiments active *Complementary to collider experiments Final results in ~ 1/2 year

50. Correctionf bkg  f bkg ) A corr (ppb)  A corr ) (ppb) Beam first order---3 Beam higher orders---10 Beam spotsize--01 Transverse asymmetry---83 High energy photons0.0040.00233 Synchrotron photons0.00150.000505 Neutrons0.0030.001-53 ep elastic0.0640.007-82 ep inelastic0.0110.003-266 Pions0.0060.00211 TOTAL0.0900.009-4314 Run I Systematics

51. Normalization Factor f  (f) Dilutions0.910.01 Polarization0.850.05 Analyzing power1.00.02 Linearity0.990.01 Run I Dilutions

52. Correctionf bkg  f bkg ) A corr (ppb)  A corr ) (ppb) Beam first order---3 Beam higher orders---15 Beam spotsize--01 Transverse asymmetry---53 High energy photons0.0040.00233 Synchrotron photons0.00150.000502 Neutrons0.0030.001-53 ep elastic0.0530.005-71 ep inelastic0.0090.002-216 Pions0.0060.00211 TOTAL0.0740.008-3017 Run II Systematics

53. Normalization Factor f  (f) Dilutions0.910.01 Polarization0.850.05 Analyzing power1.00.02 Linearity0.990.01 Run II Dilutions

54. A PV (Run I) = -176  30 (stat)  20 (syst) ppb (5  significance) A PV (Run II) = -145  28 (stat)  23 (syst) ppb (4  significance) A PV (Run I+II) = -161  21 (stat)  17 (syst) ppb (6  significance) Asymmetry Results

55.  Standard Model prediction: 0.2385 ± 0.0006 (Czarnecki, Marciano, 2000) sin 2  eff (Run I) = 0.2353 ± 0.0025 (stat) ±0.0017 (syst) (-1.0  from Standard Model) sin 2  eff (Run II) = 0.2381 ± 0.0023 (stat) ±0.0019 (syst) (-0.1  from Standard Model) sin 2  eff (Run I) = 0.2366 ± 0.0018 (stat) ±0.0014 (syst) (-0.8  from Standard Model) Electroweak Mixing Parameter