Constraints on Exotic Mixing of Three Neutrinos

TL;DR

This paper investigates constraints on exotic three-neutrino mixing models, including matter effects and various experimental data, concluding that certain exotic mechanisms cannot explain atmospheric neutrino observations but leaving room for alternative energy dependences.

Contribution

It provides a comprehensive analysis of exotic neutrino mixing scenarios, incorporating matter effects and multiple experimental constraints, to evaluate their viability against atmospheric neutrino data.

Findings

Lorentz invariance violation models are incompatible with atmospheric neutrino data.

Data allows large electron-neutrino mixing and various energy dependences of vacuum mixing.

Next-generation experiments will further constrain these exotic mixing possibilities.

Abstract

Exotic explanations are considered for atmospheric neutrino observations. Our analysis includes matter effects and the mixing of all three neutrinos under the simplifying assumption of only one relevant mixing scale. Constraints from accelerator, reactor and solar neutrinos are included. We find that the proposed mixing mechanisms based on violations of Lorentz invariance or on violations of the equivalence principle cannot explain the recent observations of atmospheric neutrino mixing. However the data still allow a wide range of energy dependences for the vacuum mixing scale, and also allow large electron-neutrino mixing of atmospheric neutrinos. Next generation long baseline experiments will constrain these possibilities.