Nucleon axial-vector form factor and radius from future neutrino experiments

TL;DR

Future neutrino experiments measuring antineutrino elastic scattering on hydrogen could significantly improve the precision of the nucleon axial-vector form factor and radius, helping to resolve existing discrepancies with lattice-QCD results.

Contribution

This work proposes using future neutrino experiments to precisely determine the nucleon axial-vector form factor and radius, addressing current uncertainties and tensions in measurements.

Findings

Projected accuracy improves existing measurements by an order of magnitude.

Potential to resolve tension with lattice-QCD determinations.

Current knowledge of vector form factors is a major uncertainty source.

Abstract

Precision measurements of antineutrino elastic scattering on hydrogen from future neutrino experiments offer a unique opportunity to access the low-energy structure of protons and neutrons. We discuss the determination of the nucleon axial-vector form factor and radius from antineutrino interactions on hydrogen that can be collected at the future Long-Baseline Neutrino Facility, and study the sources of theoretical and experimental uncertainties. The projected accuracy would improve existing measurements by $1$ order of magnitude and be competitive with contemporary lattice-QCD determinations, potentially helping to resolve the corresponding tension with measurements from (anti)neutrino elastic scattering on deuterium. We find that the current knowledge of the nucleon vector form factors could be one of the dominant sources of uncertainty. We also evaluate the constraints that can be simultaneously obtained on the absolute $\bar \nu_\mu$ flux normalization.