Clean measurements of the nucleon axial-vector and free-neutron magnetic form factors

TL;DR

This paper explores a feasible low-energy electron scattering experiment to measure the nucleon axial-vector form factor g_a(Q^2) model-independently, aiming for more accurate axial mass extraction and improved understanding of nucleon structure.

Contribution

It proposes a novel experimental approach using low-energy electron beams to measure g_a(Q^2) with higher precision and model independence than previous methods.

Findings

Feasibility of measuring g_a(Q^2) with electron scattering.

Potential for more accurate axial mass determination.

Design considerations for the experimental setup.

Abstract

We discuss the feasibility of a weak charged current experiment using a low energy electron beam. A first goal is to measure the Q^2 dependence of the axial-vector form factor g_a(Q^2). It can be measured model-independently and as robustly as for electromagnetic form factors from typical electron scattering experiments, in contrast to the methods used so far to measure g_a(Q^2). If g_a(Q^2) follows a dipole form, the axial mass can be extracted with a better accuracy than the world data altogether. The most important detection equipment would be a segmented neutron detector with good momentum and angular resolution that is symmetric about the beam direction, and covers a moderate angular range. A high intensity beam (100 uA) is necessary. Beam polarization is highly desirable as it provides a clean measurement of the backgrounds. Beam energies between 70 and 110 MeV are ideal. This range would provide a Q^2 mapping of g_a between 0.01