Family Symmetry and Single Right-Handed Neutrino Dominance in Five   Dimensions
  We consider several neutrino mass models in an extra-dimensional setting on a quantitative level. All the models are set in a five-dimensional scenario, with the standard model (SM) particles living on a brane, while three additional SM gauge singlets live in the bulk of an extra dimension, which is compactified on a S^1/Z_2 orbifold. The spontaneous breaking of an additional, continuous U(1) family symmetry is used to generate suitable neutrino mass matrices via single right-handed neutrino dominance through the corresponding five-dimensional extension of the see-saw mechanism. In this manner possible problems of this combination for some models in four dimensions could be overcome. The considered models differ with respect to the charges under the family symmetry and the nature of the five-dimensional Majorana mass term. 
Marc-Thomas Eisele, Naoyuki Haba