Improved limits on the weak, neutral, hadronic axial vector coupling constants from quasielastic scattering of polarized electrons

Abstract

In scattering polarized electrons (P1 = 44%) by 9Be at an energy of 300 MeV at angles 115 ° ~< 0 ~< 145 ° a parity violating asymmetry of Xcorr = ( 3.5 _+ 0.7 _+ 0.2) × 10-6 was measured. After correction for finite electron polarization and background we deduce an experimental asymmetry of Acx = ( -9.4 + 1.8 _+ 0.5) × 10 6. The quoted errors indicate the statistical and the systematic uncertainties, respectively. The asymmetry, which is dominated by the quasielastic cross section, is interpreted in terms of model-independent electron-nucleon coupling constants of the weak neutral current. The error limits in the sector of axial vector coupling constants have been improved by a factor of 3 over previous results. A model-dependent analysis for the Weinberg angle yields the result sin 2 0 w = 0.221 + 0.014 + 0.004.

Constraints on four-Fermi contact interactions from low-energy electroweak experiments

“…has been measured in eD-scattering at SLAC [12], in eC scattering at Bates [13] and in eBe scattering at Mainz [14]. Here dσ L(R) denotes the differential cross section of the left-(right-) handed lepton scattering off target.…”

“…The experiment was performed at the mean momentum transfer Q 2 0.2025 GeV 2 . In this experiment, the asymmetry parameter A Mainz can be expressed by the following combination of the model independent parameters [14]; 19) and the experimental result is given by…”

Examination of higher-order twist contributions in parity-violating deep-inelastic electron-deuteron scattering

“…The results of measuring this asymmetry in the early experiments at the SLAC National Accelerator Laboratory led to the correct description of neutral weak interactions well before the discovery of the Z boson at CERN and provided a measurement of the weak mixing angle sin 2 θ W . Since then parity-violating electron scattering from various targets was studied at JLab [4][5][6][7], MIT/Bates [8,9], Mainz [10,11], and SLAC [12] as a tool for probing physics beyond the SM and hadronic structure. Currently, an active program is underway at JLab to continue these studies with a new level of precision.…”

Parity violating pion electroproduction off the nucleon

“…The pioneering experiment to measure PV asymmetries has been performed at SLAC [1] by deep inelastic electron scattering on a deuterium target. This experiment has been followed by investigations of PV quasifree scattering off 9 B at Mainz [2] and PV elastic scattering off 12 C at MIT/Bates [3]. In the latter case the momentum transfer was only q 2 = −(150 MeV) 2 , leading to the tiny asymmetry A = (0.60 ± 0.14 ± 0.02) · 10 −6 .…”