Extraction of the Axial Nucleon Form Factor from Neutrino Experiments on Deuterium

TL;DR

This paper develops new parameterizations of nucleon form factors, enabling more accurate extraction of the axial form factor from neutrino experiments on deuterium, with implications for modeling neutrino interactions and future experiments.

Contribution

It introduces improved form factor parameterizations that incorporate quark-hadron duality and relate elastic and inelastic scattering, refining axial form factor extraction from neutrino data.

Findings

Updated axial mass value: 1.014 ± 0.014 GeV/c^2

Form factor parameterizations fit low Q^2 data well

Predictions for high Q^2 can be tested in future experiments

Abstract

We present new parameterizations of vector and axial nucleon form factors. We maintain an excellent descriptions of the form factors at low momentum transfers ($Q^2$), where the spatial structure of the nucleon is important, and use the Nachtman scaling variable $\xi$ to relate elastic and inelastic form factors and impose quark-hadron duality constraints at high $Q^2$ where the quark structure dominates. We use the new vector form factors to re-extract updated values of the axial form factor from $\numu$ experiments on deuterium. We obtain an updated world average value from $\numu$d, $\numubar$H and pion electroproduction experiments of $M_{A}$ = $1.014 \pm 0.014 GeV/c^2$. Our parameterizations are useful in modeling $\nu$ interactions at low energies (e.g. for $\numu$ oscillations experiments). The predictions for high $Q^2$ can be tested in the next generation electron and $\numu$ scattering experiments.