Neutrino mass ordering obscured by non-standard interactions

TL;DR

The paper demonstrates that the current indication of neutrino mass ordering is nullified when considering non-standard interactions, highlighting the importance of accounting for such interactions in future analyses.

Contribution

It shows that non-standard interactions can obscure the neutrino mass ordering signal, challenging previous interpretations based on standard oscillation models.

Findings

Current NMO indication is washed out with NSI assumptions.

Neutral-current NSI involving e-tau flavors affect NMO measurements.

Implication for future neutrino experiments to consider NSI effects.

Abstract

One of the major open questions in particle physics is the issue of the neutrino mass ordering (NMO). The current data of the two long-baseline experiments NO$\nu$A and T2K, interpreted in the standard 3-flavor scenario, provide a $\sim2.4\sigma$ indication in favor of the normal neutrino mass ordering. We show that such an indication is completely washed out if one assumes the existence of neutral-current non-standard interactions (NSI) of the flavor changing type involving the $e-\tau$ flavors. This implies that the claim for a discovery of the NMO will require a careful consideration of the impact of hypothetical NSI.