MiniBooNE Results and Neutrino Schemes with 2 sterile Neutrinos: Possible Mass Orderings and Observables related to Neutrino Masses

TL;DR

This paper explores eight possible neutrino mass orderings with two sterile neutrinos, analyzing their implications for observable mass-related phenomena and how experiments can distinguish between these scenarios.

Contribution

It systematically classifies all eight mass orderings with two sterile neutrinos and evaluates their experimental signatures across multiple observables.

Findings

Six scenarios predict positive signals in KATRIN and neutrinoless double beta decay.

Mass orderings influence the sum of neutrino masses constrained by cosmology.

High-energy astrophysical neutrino decays could help discriminate between scenarios.

Abstract

The MiniBooNE and LSND experiments are compatible with each other when two sterile neutrinos are added to the three active ones. In this case there are eight possible mass orderings. In two of them both sterile neutrinos are heavier than the three active ones. In the next two scenarios both sterile neutrinos are lighter than the three active ones. The remaining four scenarios have one sterile neutrino heavier and another lighter than the three active ones. We analyze all scenarios with respect to their predictions for mass-related observables. These are the sum of neutrino masses as constrained by cosmological observations, the kinematic mass parameter as measurable in the KATRIN experiment, and the effective mass governing neutrinoless double beta decay. It is investigated how these non-oscillation probes can distinguish between the eight scenarios. Six of the eight possible mass orderings predict positive signals in the KATRIN and future neutrinoless double beta decay experiments. We also remark on scenarios with three sterile neutrinos. In addition we make some comments on the possibility of using decays of high energy astrophysical neutrinos to discriminate between the mass orderings in presence of two sterile neutrinos.