A Sterile Neutrino at DUNE

TL;DR

This paper explores DUNE's ability to detect and analyze a potential fourth, sterile neutrino, including its mixing with known neutrinos, CP violation effects, and implications for the standard three-neutrino model.

Contribution

It assesses DUNE's sensitivity to a new sterile neutrino across a broad parameter space and its capacity to measure new oscillation parameters and CP violation sources.

Findings

DUNE can probe unexplored regions of sterile neutrino parameter space.

DUNE can measure new oscillation parameters with high precision.

DUNE can identify multiple sources of CP violation if a sterile neutrino exists.

Abstract

We investigate the potential for the Deep Underground Neutrino Experiment (DUNE) to probe the existence and effects of a fourth neutrino mass-eigenstate. We study the mixing of the fourth mass-eigenstate with the three active neutrinos of the Standard Model, including the effects of new sources of CP-invariance violation, for a wide range of new mass-squared differences, from lower than 10^-5 eV^2 to higher than 1 eV^2. DUNE is sensitive to previously unexplored regions of the mixing angle - mass-squared difference parameter space. If there is a fourth neutrino, in some regions of the parameter space, DUNE is able to measure the new oscillation parameters (some very precisely) and clearly identify two independent sources of CP-invariance violation. Finally, we use the hypothesis that there are four neutrino mass-eigenstates in order to ascertain how well DUNE can test the limits of the three-massive-neutrinos paradigm. In this way, we briefly explore whether light sterile neutrinos can serve as proxies for other, in principle unknown, phenomena that might manifest themselves in long-baseline neutrino oscillation experiments.