Abstract
We study the model-building conditions under which a sizable -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 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 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 and mixings that can fully explain the current atmospheric and solar neutrino data.
- Received 3 February 2003
DOI:https://doi.org/10.1103/PhysRevD.67.113001
©2003 American Physical Society