6533b833fe1ef96bd129b8c2

RESEARCH PRODUCT

Measurement of the parity violating asymmetry in the quasielastic electron-deuteron scattering and improved determination of the magnetic strange form factor and the isovector anapole radiative correction

subject

description

A new measurement of the parity-violating asymmetry in the electron-deuteron quasielastic scattering for backward angles at $⟨{Q}^{2}⟩=0.224\text{ }\text{ }{(\mathrm{GeV}/c)}^{2}$, obtained in the A4 experiment at the Mainz Microtron accelerator (MAMI) facility, is presented. The measured asymmetry is ${A}_{PV}^{d}=(\ensuremath{-}20.11\ifmmode\pm\else\textpm\fi{}0.8{7}_{\mathrm{stat}}\ifmmode\pm\else\textpm\fi{}\phantom{\rule{0ex}{0ex}}1.0{3}_{\mathrm{sys}})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$. A combination of these data with the proton measurements of the parity-violating asymmetry in the A4 experiment yields a value for the effective isovector axial-vector form factor of ${G}_{A}^{e,(T=1)}=\ensuremath{-}0.19\ifmmode\pm\else\textpm\fi{}0.43$ and ${R}_{A}^{(T=1),\mathrm{anap}}=\ensuremath{-}0.41\ifmmode\pm\else\textpm\fi{}0.35$ for the anapole radiative correction. When combined with a reanalysis of measurements obtained in the G0 experiment at the Thomas Jefferson National Accelerator Facility, the uncertainties are further reduced to ${G}_{M}^{s}=0.17\ifmmode\pm\else\textpm\fi{}0.11$ for the magnetic strange form factors, and ${R}_{A}^{(T=1),\mathrm{anap}}=\ensuremath{-}0.54\ifmmode\pm\else\textpm\fi{}0.26$.