# Curtailing the Dark Side in Non-Standard Neutrino Interactions

## TL;DR

This paper investigates how non-standard neutrino interactions affect flavor evolution and explores experimental methods to resolve degeneracies, especially focusing on the potential of future neutrino scattering experiments to clarify the neutrino mass ordering.

## Contribution

It provides a combined analysis of oscillation and scattering data to identify conditions under which the LMA-Dark degeneracy can be broken, highlighting the role of mediator mass and experimental setups.

## Key findings

- Degeneracy can be lifted with down quark interactions.
- Constraints depend on mediator mass; lighter mediators require future experiments.
- Future coherent scattering experiments can resolve the degeneracy or confirm new interactions.

## Abstract

In presence of non-standard neutrino interactions the neutrino flavor evolution equation is affected by a degeneracy which leads to the so-called LMA-Dark solution. It requires a solar mixing angle in the second octant and implies an ambiguity in the neutrino mass ordering. Non-oscillation experiments are required to break this degeneracy. We perform a combined analysis of data from oscillation experiments with the neutrino scattering experiments CHARM and NuTeV. We find that the degeneracy can be lifted if the non-standard neutrino interactions take place with down quarks, but it remains for up quarks. However, CHARM and NuTeV constraints apply only if the new interactions take place through mediators not much lighter than the electroweak scale. For light mediators we consider the possibility to resolve the degeneracy by using data from future coherent neutrino-nucleus scattering experiments. We find that, for an experiment using a stopped-pion neutrino source, the LMA-Dark degeneracy will either be resolved, or the presence of new interactions in the neutrino sector will be established with high significance.