Searching for beyond-Standard-Model solar neutrino interactions using directional detectors

TL;DR

This paper forecasts the potential of large-scale directional gaseous detectors to explore non-standard neutrino interactions and new light mediators by analyzing solar neutrino recoil data with improved sensitivity.

Contribution

It introduces a framework for using upcoming 30 m³ MPGDs to detect beyond-Standard-Model neutrino interactions through recoil energy and angle measurements.

Findings

Sensitivity approaches Borexino's with background reduction

Directionality enables event-by-event neutrino energy reconstruction

Motivates development of small-scale directional gas detectors

Abstract

Micro-pattern gaseous detectors (MPGDs) are a class of technologies that enable the full three-dimensional spatial reconstruction of ionisation tracks from nuclear and electron recoils in gas. Anticipating near-future 30 m$^3$-scale time projection chambers with MPGD-based readout, we forecast the sensitivity of such directionally-sensitive low-energy recoil detectors to neutrino interactions beyond the Standard Model. We work in the framework of neutrino non-standard interactions (NSIs), and calculate the combined recoil energy-angle distributions of the electron recoil signal generated by solar neutrinos in atmospheric-pressure He:CF$_4$ gas. We estimate the expected exclusion limits that such an experiment could place on various NSI parameters, as well as the mass and coupling of a new light mediator that interacts with electrons and neutrinos. We find that with an achievable background reduction of around a factor of ten from current estimates for a 30 m$^3$ optical-readout detector using this gas mixture, sensitivity to NSI parameters would already approach Borexino's sensitivity. Directionality also allows for event-by-event neutrino energy reconstruction, which would provide a means to resolve some parameter degeneracies present in the modified neutrino cross section in this formalism. Our results strongly motivate the development of small-scale directionally-sensitive gas detectors for neutrino physics.