Updating $\nu_{3}$ lifetime from solar antineutrino spectra

TL;DR

This paper derives new, significantly improved limits on the lifetime of the third neutrino mass state by analyzing solar antineutrino spectra from KamLAND and Borexino, considering Majorana decay channels.

Contribution

It provides the first constraints on $ u_3$ decay lifetime from solar antineutrino data, surpassing previous atmospheric and long-baseline bounds by five orders of magnitude.

Findings

Limits on $ au_3/m_3$ are $ ext{≥}7 imes 10^{-5}$ s/eV and $ ext{≥}1 imes 10^{-5}$ s/eV for different decay channels.

The bounds are five orders of magnitude stronger than previous atmospheric and long-baseline limits.

The analysis considers scalar and pseudo-scalar interactions in neutrino decay channels.

Abstract

We study the production of antineutrinos from the solar neutrinos due the Majorana neutrino decays of neutrino to antineutrino. Using the antineutrino spectra from KamLAND and Borexino, we present newest limits on the lifetime of $\nu_{3}$ in this scenario. We consider $\nu_{3} \rightarrow \bar{\nu}_{1} + X$ and $\nu_{3} \rightarrow \bar{\nu}_{2} + X$ channels assuming scalar or pseudo-scalar interactions. For hierarchical mass-splittings, the limits obtained by us are $\tau_{3}/m_{3}~\geq 7\times 10^{-5} s/eV$ and $\tau_{3}/m_{3}~\geq 1\times 10^{-5} s/eV$ for the two channels at $90\%$ C.L. We found that the newest bound is five orders of magnitude better than the atmospheric and long-baseline bounds.