Restricting Sterile Neutrinos by Neutrinoless Double Beta Decay

TL;DR

This paper refines bounds on sterile neutrino parameters using neutrinoless double beta decay data, providing a simple analytic expression and analyzing dependencies on CP phases and neutrino mass spectra, with implications for existing sterile neutrino hints.

Contribution

It introduces a compact analytic formula for sterile neutrino bounds in the $\Delta m^2_{41} - \sin^2 2 heta_{14}$ plane, incorporating CP phases and mass spectrum effects, and compares these with experimental hints.

Findings

$0 uetaeta$ decay bounds exclude some sterile neutrino parameter regions.

Future experiments could tighten constraints on sterile neutrino parameters.

Current bounds conflict with certain positive sterile neutrino indications.

Abstract

The bounds on parameters of the eV and higher scale sterile neutrinos from the $0\nu \beta \beta$ decay have been refined and updated. We present a simple and compact analytic expression for the bound in the $\Delta m^2_{41} - \sin^2 2\theta_{14}$ plane, which includes all relevant parameters. Dependencies of the bound on unknown CP-phases and the type of mass spectrum of light neutrinos (mass ordering and level of degeneracy) are studied in detail. We have computed the bounds using the latest and most stringent data from KamLAND-Zen. The projected constraints from future experiments are estimated. The obtained bounds are confronted with positive indications of the presence of sterile neutrinos as well as with the other existing bounds. The $0\nu \beta \beta$ decay results exclude the regions of parameters implied by BEST and Neutrino-4, and the regions indicated by LSND and MiniBooNE are in conflict with $0\nu \beta \beta$ results combined with $\nu_\mu-$ disappearance bounds.