Neutron knockout in neutral-current neutrino-oxygen interactions

TL;DR

This paper calculates neutron knockout cross sections in neutral-current neutrino-oxygen interactions to improve background modeling for neutrino detection experiments, considering nuclear effects and strange-quark contributions.

Contribution

It provides the first detailed cross section calculations using realistic nuclear spectral functions for this process, including the impact of strange-quark contributions.

Findings

Neutron knockout cross sections are quantified for relevant kinematic ranges.

Strange-quark contributions significantly affect the neutral-current axial form factor.

Uncertainties based on experimental data are estimated for the cross sections.

Abstract

The ongoing and future searches for diffuse supernova neutrinos and sterile neutrinos carried out with large water-Cherenkov detectors require a precise determination of the backgrounds, especially those involving gamma rays. Of great importance, in this context, is the process of neutron knockout through neutral-current scattering of atmospheric neutrinos on oxygen. Nuclear reinteractions of the produced neutron may in fact lead to the production of gamma rays of energies high enough to mimic the processes of interest. In this Letter, we focus on the kinematical range suitable for simulations of atmospheric-neutrino interactions and provide the neutron-knockout cross sections computed using the formalism based on realistic nuclear spectral function. The role of the strange-quark contribution to the neutral-current axial form factor is also analyzed. Based on the available experimental information, we give an estimate of the associated uncertainty.