We propose a model with one large sub-mm size extra dimension in which the gravity and right-handed neutrino propagate, but the three standard model (SM) families are confined to fat branes of ${\mathrm{TeV}}^{-1}$ size or smaller. The charged leptons and the light neutrinos receive mass from the five-dimensional Yukawa couplings with the SM singlet neutrino via electroweak Higgs, while the Kaluza-Klein excitations of the SM singlet neutrino gets large TeV scale masses from the five-dimensional Yukawa coupling with an electroweak singlet Higgs. The model gives nonhierarchical light neutrino masses, accommodates hierarchical charged lepton masses, and naturally explains why the light neutrino masses are so much smaller compared to the charged lepton masses. Large neutrino mixing is naturally expected in this scenario. The light neutrinos are Dirac particles in this model, hence neutrinoless double beta decay is not allowed. The model also has several interesting collider implications and can be tested at the LHC.

• Received 30 November 2006

DOI:https://doi.org/10.1103/PhysRevD.76.015003