Neutrinoless double beta decay with light sterile neutrinos: the contact terms

TL;DR

This paper investigates how light sterile neutrinos with masses below 1 GeV influence neutrinoless double-beta decay, providing new calculations of short-range couplings and their effects on decay half-lives.

Contribution

The authors generalize matching methods to determine the mass dependence of short-range couplings in neutrinoless double-beta decay for models with light sterile neutrinos.

Findings

Significant impact on decay half-life for sterile neutrino masses 200-800 MeV.

Derived new short-range coupling formulas in chiral effective field theory.

Analyzed effects within minimal νSM and left-right symmetric models.

Abstract

We study neutrinoless double-beta decay in extensions of the Standard Model that include $n$ right-handed neutrino singlets, with masses $m_s$ below the GeV scale. Generalizing recently developed matching methods, we determine the $m_s$ dependence of the short-range $nn \to pp$ couplings that appear to leading order in the chiral effective field theory description of neutrinoless double beta decay. We focus on two scenarios, corresponding to the minimal $\nu$SM and left-right symmetric models. We illustrate the impact of our new results in the case of the $\nu$SM, showing a significant impact on the neutrinoless double-beta decay half-life when $m_s$ is in the 200-800 MeV range.