Neutrinoless double beta decay from singlet neutrinos in extra dimensions

Abstract

We study the model-building conditions under which a sizable $0\ensuremath{\nu}\ensuremath{\beta}\ensuremath{\beta}$-decay signal to the recently reported level of 0.4 eV is due to Kaluza-Klein singlet neutrinos in theories with large extra dimensions. Our analysis is based on 5-dimensional singlet-neutrino models compactified on an ${S}^{1}{/Z}_{2}$ orbifold, where the standard-model fields are localized on a 3-brane. We show that a successful interpretation of a positive signal within the above minimal 5-dimensional framework would require a non-vanishing shift of the 3-brane from the orbifold fixed points by an amount smaller than the typical scale $(100\mathrm{MeV}{)}^{\ensuremath{-}1}$ characterizing the Fermi nuclear momentum. The resulting 5-dimensional models predict a sizable effective Majorana-neutrino mass that could be several orders of magnitude larger than the light neutrino masses. Most interestingly, the brane-shifted models with only one bulk sterile neutrino also predict novel trigonometric textures leading to mass scenarios with hierarchical active neutrinos and large ${\ensuremath{\nu}}_{\ensuremath{\mu}}\ensuremath{-}{\ensuremath{\nu}}_{\ensuremath{\tau}}$ and ${\ensuremath{\nu}}_{e}\ensuremath{-}{\ensuremath{\nu}}_{\ensuremath{\mu}}$ mixings that can fully explain the current atmospheric and solar neutrino data.