Strange Quark Contributions to Parity-Violating Asymmetries in the Backward Angle G0 Electron Scattering Experiment

TL;DR

This study measures parity-violating asymmetries in electron scattering to quantify strange quark contributions and anapole effects in nucleons at specific momentum transfers, providing new insights into nucleon structure.

Contribution

It presents the first measurements of strange quark contributions and anapole moment effects in nucleons at these momentum transfers.

Findings

Strange quark contributions are less than 10% of nucleon form factors.

First measurement of anapole moment effects at these momentum transfers.

Results refine understanding of nucleon internal structure.

Abstract

We have measured parity-violating asymmetries in elastic electron-proton and quasi-elastic electron-deuteron scattering at Q^2 = 0.22 and 0.63 GeV^2. They are sensitive to strange quark contributions to currents in the nucleon, and to the nucleon axial current. The results indicate strange quark contributions of < 10% of the charge and magnetic nucleon form factors at these four-momentum transfers. We also present the first measurement of anapole moment effects in the axial current at these four-momentum transfers.