skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Observation of Parity Nonconservation in Moller Scattering

Abstract

The authors report a measurement of the parity-violating asymmetry in fixed target electron-electron (Moeller) scattering: A{sub PV} = (-175 {+-} 30 (stat.) {+-} 20 (syst.)) x 10{sup -9}. This first direct observation of parity nonconservation in Moeller scattering leads to a measurement of the electron's weak charge at low energy Q{sub W}{sup e} = -0.053 {+-} 0.011. This is consistent with the Standard Model expectation at the current level of precision: sin{sup 2} {theta}{sub W} (M{sub Z}){sub {ovr MS}} = 0.0024 (stat.) {+-} 0.0016 (syst.) {+-} 0.0006 (theory).

Authors:
Publication Date:
Research Org.:
Stanford Linear Accelerator Center, Menlo Park, CA (US)
Sponsoring Org.:
USDOE Office of Science (US)
OSTI Identifier:
826909
Report Number(s):
SLAC-PUB-10270
TRN: US0404685
DOE Contract Number:
AC03-76SF00515
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 16 Jan 2004
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ACCURACY; ASYMMETRY; MOELLER SCATTERING; P INVARIANCE; SCATTERING; STANDARD MODEL; TARGETS

Citation Formats

Anthony, P. Observation of Parity Nonconservation in Moller Scattering. United States: N. p., 2004. Web. doi:10.2172/826909.
Copy to clipboard
Anthony, P. Observation of Parity Nonconservation in Moller Scattering. United States. doi:10.2172/826909.
Copy to clipboard
Anthony, P. Fri . "Observation of Parity Nonconservation in Moller Scattering". United States. doi:10.2172/826909. https://www.osti.gov/servlets/purl/826909.
Copy to clipboard
@article{osti_826909,
title = {Observation of Parity Nonconservation in Moller Scattering},
author = {Anthony, P.},
abstractNote = {The authors report a measurement of the parity-violating asymmetry in fixed target electron-electron (Moeller) scattering: A{sub PV} = (-175 {+-} 30 (stat.) {+-} 20 (syst.)) x 10{sup -9}. This first direct observation of parity nonconservation in Moeller scattering leads to a measurement of the electron's weak charge at low energy Q{sub W}{sup e} = -0.053 {+-} 0.011. This is consistent with the Standard Model expectation at the current level of precision: sin{sup 2} {theta}{sub W} (M{sub Z}){sub {ovr MS}} = 0.0024 (stat.) {+-} 0.0016 (syst.) {+-} 0.0006 (theory).},
doi = {10.2172/826909},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Fri Jan 16 00:00:00 EST 2004},
month = {Fri Jan 16 00:00:00 EST 2004}
}
Copy to clipboard
Technical Report:
View Technical Report
DOI:  10.2172/826909
Save / Share:
Export Metadata
Save to My Library
You must Sign In or Create an Account in order to save documents to your library.

  • ;
    This thesis reports on the E158 experiment at Stanford Linear Accelerator Center (SLAC), which has made the first observation of the parity non-conserving asymmetry in Moller scattering. Longitudinally polarized 48 GeV electrons are scattered off unpolarized (atomic) electrons in a liquid hydrogen target with an average Q{sup 2} of 0.027 GeV{sup 2}. The asymmetry in this process is proportional to (1/4 - sin{sup 2}{theta}{sub W}), where sin{sup 2} {theta}{sub W} gives the weak mixing angle. The thesis describes the experiment in detail, with a particular focus on the design and construction of the electromagnetic calorimeter. This calorimeter was the primarymore » detector in the experiment used to measure the flux of the scattered Moller electrons and eP electrons. It employed the quartz fiber calorimetry technique, and was built at Syracuse University. The preliminary results from the first experimental data taken in spring 2002 give A{sub PV} = -151.9 {+-} 29.0(stat) {+-} 32.5(syst) parts per billion. This in turn gives sin{sup 2} {theta}{sub W} = 0.2371 {+-} 0.0025 {+-} 0.0027, which is consistent with the Standard Model prediction (0.2386 {+-} 0.0006).« less

  • The E158 experiment at SLAC will make the first measurement of parity violation in Moller scattering. The left-right cross-section asymmetry (ALR) in the elastic scattering of a 45-GeV polarized electron beam with unpolarized electrons in a liquid hydrogen target will be measured. This will give a precise measurement of the weak mixing angle, with delta(sin{sup 2} theta{sub W}{sup eff}) {approximately} 0.0008 (at Q{sup 2} = 0.03GeV{sup 2}).

  • This thesis reports on E158, an experiment located in End Station A at the Stanford Linear Accelerator Center (SLAC). E158 has made the first observation of the parity violating right-left asymmetry (A{sub PV}) in fixed-target low-Q{sup 2} Moeller scattering. At tree level, A{sub PV} (expected to be around -150 ppb) is directly proportional to 1/4 - sin{sup 2} {theta}{sub W}. A precision measurement of A{sub PV} at low Q{sup 2} allows the running of sin{sup 2} {theta}{sub W} to be compared to the Standard Model prediction. Disagreements between the two might provide evidence for new physics at the TeV scale.more » This thesis presents the first physics data from E158, taken in the spring of 2002. The data were taken by scattering longitudinally polarized electrons at 45.0 and 48.3 GeV off a liquid hydrogen target at a Q{sup 2} of 0.027 GeV{sup 2}. A 60 meter long spectrometer/collimator system and a cooper-quartz calorimeter were used to detect the Moeller signal electrons. Both devices will be described in detail. The right-left parity violating asymmetry in Moeller scattering has been measured to be -152.3 {+-} 29.0(stat) {+-} 30.9(syst) ppb. The value of sin{sup 2} {theta}{sub W} derived from this measurement is 0.2370 {+-} 0.0025(stat) {+-} 0.0026(syst), in comparison with the Standard Model prediction of 0.2387 {+-} 0.0007.« less

  • ; ; ; ...
    We compute a full set of the first order QED corrections to the parity-violating observables in polarized Moeller scattering. We employ a covariant method of removing infrared divergences, computing corrections without introducing any unphysical parameters. When applied to the kinematics of the SLAC E158 experiment, the QED corrections reduce the parity violating asymmetry by 4.5%. We combine our results with the previous calculations of the first-order electroweak corrections and obtain the complete {Omicron}({alpha}) prescription for relating the experimental asymmetry A{sub LR} to the low-energy value of the weak mixing angle sin{sup 2} {theta}{sub W}. Our results are applicable to themore » recent measurement of A{sub LR} by the SLAC E158 collaboration, as well as to the future parity violation experiments.« less

  • Recent observations of parity violation in inelastic scattering of electrons at high energy is discussed with reference to the process e(polarized) + D(unpolarized) ..-->.. e + X. The kinetics of this process, the idealized case of scattering from free quark targets, experimental techniques and results, and relations to atomic physics of parity violation in bismuth and thallium atoms with a model independent analysis. 17 references. (JFP)