Influence of a keV sterile neutrino on neutrino-less double beta decay -- how things changed in the recent years

TL;DR

This paper updates the analysis of keV sterile neutrinos' impact on neutrino-less double beta decay using recent observational data and mixing angle measurements, concluding their influence is minimal under current constraints.

Contribution

It provides an updated assessment of keV sterile neutrinos' effect on double beta decay considering new X-ray bounds and the latest mixing angle data, extending previous studies.

Findings

Recent observational bounds limit the influence of keV sterile neutrinos on decay rates.

The impact remains small even if keV sterile neutrinos constitute only part of Dark Matter.

New data reinforce the minimal role of keV sterile neutrinos in neutrino-less double beta decay.

Abstract

Earlier studies of the influence of Dark Matter keV sterile neutrinos on neutrino-less double beta decay concluded that there is no significant modification of the decay rate. These studies have focused only on a mass of the keV sterile neutrino above 2 and 4 keV, respectively, as motivated by certain production mechanisms. On the other hand, alternative production mechanisms have been proposed, which relax the lower limit for the mass, and new experimental data are available, too. For this reason, an updated study is timely and worthwhile. We focus on the most recent data, i.e., the newest Chandra and XMM-Newton observational bounds on the X-ray line originating from radiative keV sterile neutrino decay, as well as the new measurement of the previously unknown leptonic mixing angle $\theta_{13}$. While the previous works might have been a little short-sighted, the new observational bounds do indeed render any influences of keV sterile neutrinos on neutrino-less double beta decay small. This conclusion even holds in case not all the Dark Matter is made up of keV sterile neutrinos.