Axial-vector neutral-current measurements in coherent elastic neutrino-nucleus scattering experiments

TL;DR

This paper explores the potential to measure axial-current contributions in coherent elastic neutrino-nucleus scattering (CEνNS), identifying fluorine-based compounds like C3F8 as promising targets to probe spin-dependent interactions and new physics.

Contribution

It demonstrates that CEνNS experiments with fluorine compounds can indirectly measure axial couplings at about 10% accuracy, advancing the understanding of axial contributions in neutrino interactions.

Findings

Fluorine-based compounds are optimal for axial-current measurements.

C3F8 can enable ~10% determination of axial couplings.

Measurements can probe spin-dependent new physics scenarios.

Abstract

Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) is predominantly governed by vector neutral-current interactions, with subleading contributions arising from the axial current in nuclei with non-zero ground-state spin. Experimentally, the extraction of axial-current contributions has been so far of little interest, mainly because of the challenges its measurement entail. In this work, we investigate the relative size of the vector and axial components for target materials currently employed by the neutrino and dark matter experimental communities. We identify fluorine-based compounds as the most promising targets for probing the axial-current event rate. Among them, octafluoropropane ($\text{C}_3\text{F}_8$) emerges as a particularly suitable candidate, given its widespread use in spin-dependent dark matter searches and its relevance for upcoming dedicated CE$\nu$NS experiments. Considering both pion decay-at-rest and reactor neutrino fluxes, we show that such measurements can allow an indirect determination of the axial coupling at the $\sim 10\%$ level, depending on flux uncertainties and detector thresholds. We further emphasize that measurements of the axial current will allow to probe spin-dependent new physics scenarios through CE$\nu$NS.