Limit on sterile neutrino contribution from the Mainz Neutrino Mass Experiment

TL;DR

This paper analyzes Mainz Neutrino Mass data to search for a sterile neutrino with a mass around eV, finding no evidence and setting limits on its possible contribution.

Contribution

First analysis of Mainz data to constrain sterile neutrino parameters using beta-decay spectra, providing new limits on their mass and mixing.

Findings

No evidence of a fourth light neutrino mass state.

Limits established on sterile neutrino mass and mixing angle.

Results constrain models predicting sterile neutrinos around eV scale.

Abstract

The recent analysis of the normalization of reactor antineutrino data, the calibration data of solar neutrino experiments using gallium targets, and the results from the neutrino oscillation experiment MiniBooNE suggest the existence of a fourth light neutrino mass state with a mass of O(eV), which contributes to the electron neutrino with a sizable mixing angle. Since we know from measurements of the width of the Z0 resonance that there are only three active neutrinos, a fourth neutrino should be sterile (i.e., interact only via gravity). The corresponding fourth neutrino mass state should be visible as an additional kink in beta-decay spectra. In this work the phase II data of the Mainz Neutrino Mass Experiment have been analyzed searching for a possible contribution of a fourth light neutrino mass state. No signature of such a fourth mass state has been found and limits on the mass and the mixing of this fourth mass states are derived.