nuMSM--Predictions for Neutrinoless Double Beta Decay

TL;DR

The paper investigates the neutrinoless double beta decay effective mass $m_{\beta\beta}$ within the νMSM, a Standard Model extension that adds three sterile neutrinos to explain dark matter and baryogenesis. It shows the keV-scale sterile neutrino contributing to $m_{\beta\beta}$ is negligible due to its tiny mixing, allowing the standard three-active-neutrino analysis with $m_{\min} \lesssim 10^{-5}\mathrm{eV}$. Using current oscillation data, it derives $m_{\beta\beta}^{NH}$ in the range $1.3$–$3.4$ meV and $m_{\beta\beta}^{IH}$ in the range $13$–$50$ meV, with possible cancellations in NH that can reduce $m_{\beta\beta}^{NH}$ to zero at 3σ. This work links cosmological constraints on the νMSM to concrete, testable predictions for $0\nu\beta\beta$ decay, guiding future experimental sensitivity.

Abstract

We give the prediction on the effective Majorana mass for neutrinoless double $β$ decay in a simple extension of the Standard Model (nuMSM). The model adds three right-handed neutrinos with masses smaller than the electroweak scale, and explains dark matter of the Universe. This leads to constraints 1.3meV<m_{bb}^{NH}<3.4meV in normal neutrino mass hierarchy and 13meV<m_{bb}^{IH}<50meV in inverted hierarchy.