Deuterium target data for precision neutrino-nucleus cross sections

TL;DR

This paper presents a model-independent analysis of neutrino-deuteron scattering data to accurately determine the axial form factor and related cross sections, reducing uncertainties in neutrino-nucleus interaction predictions.

Contribution

It introduces a systematic, model-independent method for extracting the axial form factor from scattering data, improving the accuracy of neutrino cross section calculations.

Findings

Axial radius squared: 0.46(22) fm^2

Neutrino-neutron cross section at 1 GeV: 10.1(0.9) x 10^{-39} cm^2

Methodology can be extended to other amplitudes and processes.

Abstract

Amplitudes derived from scattering data on elementary targets are basic inputs to neutrino-nucleus cross section predictions. A prominent example is the isovector axial nucleon form factor, $F_A(q^2)$, which controls charged current signal processes at accelerator-based neutrino oscillation experiments. Previous extractions of $F_A$ from neutrino-deuteron scattering data rely on a dipole shape assumption that introduces an unquantified error. A new analysis of world data for neutrino-deuteron scattering is performed using a model-independent, and systematically improvable, representation of $F_A$. A complete error budget for the nucleon isovector axial radius leads to $r_A^2=0.46(22) \,{\rm fm}^2$, with a much larger uncertainty than determined in the original analyses. The quasielastic neutrino-neutron cross section is determined as $\sigma(\nu_\mu n \to \mu^- p)\big|_{E_\nu =1\,{\rm GeV}} = 10.1(0.9) \times 10^{-39}{\rm cm}^2$. The propagation of nucleon-level constraints and uncertainties to nuclear cross sections is illustrated using MINERvA data and the GENIE event generator. These techniques can be readily extended to other amplitudes and processes.