Revising Neutrino Oscillation Parameter Space With Direct Flavor-Changing Interactions

TL;DR

This paper introduces a framework for direct neutrino flavor-changing interactions and demonstrates their significant impact on interpreting neutrino oscillation experiments, especially in small transition probability regimes.

Contribution

It develops a unified parameterization for direct flavor-changing interactions within neutrino mixing models and assesses their effects on experimental interpretations.

Findings

Small direct interactions can significantly alter oscillation interpretations.

NOMAD experiment is highly sensitive to direct flavor violation effects.

Muon collider neutrino beams could provide precise tests for flavor violation.

Abstract

We formulate direct, neutrino flavor-changing interactions in a framework that fits smoothly with the parameterization of two-and three-state mixing of massive neutrino states. We show that even small direct interaction strengths could have important consequences for the interpretation of currently running and proposed oscillation experiments. The oscillation amplitude and the borders of the allowed regions in two-and three-flavor mixing parameter space can be sensitieve to the presence of direct interactions when the transition probability is small. We use extensively the high sensitivity of the NOMAD experiment to illustrate potentially large effects from small, direct flavor violation. In the purely leptonic sector, we find that the clean muon neutrino and electron neutrino beams from a muon collider could provide the sharpest tests of direct flavor violation.