Cultural Interlude Emlyn Hughes Caltech DOE HEP Review July 21, 2004 Final Results from SLAC Experiment E158 “Measurement of the Electroweak Mixing Angle”

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

Q (GeV) sin 2  w Status in 1999 ~5%

Parity Violation in Electron-Electron Scattering  Parity conserving Parity violating e-

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

UC Berkeley Caltech Jefferson Lab Princeton Saclay SLAC Smith College Syracuse UMass Virginia 7 Ph.D. Students 60 physicists Sept 97: EPAC approval : 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 Spokespeople: K. Kumar, EWH, P. Souder

End Station A

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

STATISTICS # electrons per pulse10 7 Rep rate (120 Hz)10 9 Seconds/day days10 16  A ~ 10 -8

II. BEAM MONITORING

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

III. False Asymmetries source ~few hours *48 vs. 45 GeV energy ~ few days

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

A PV vs. time ppb

Asymmetry Results

A PV =  128  14 (stat)  12 (syst) ppb sin 2  = ± (stat) ± (syst) At Q 2 = (GeV/c) 2 …. w All E158 Data PRELIMINARY MS sin 2  = ± w MS Theory:

Q (GeV) sin 2  w Status in 1999

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 Kozlov Porsev Tupitsyn Johnson Bednyhakov Soff Kuchiev Flambaum 2003

77 Status Today sin 2  w

Beyond Standard Model Implications... *Limit on  LL ~ 10 TeV *Limit on SO(10) Z’ ~ 900 GeV *Limit on lepton flavor violating coupling ~ 0.01G F (95% confidence level)

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