  We discuss a six dimensional mass generation for the neutrinos. Active
neutrinos live on a three-brane and interact via a brane localized mass term
with a bulk six-dimensional standard model singlet (sterile) Weyl fermion, the
two dimensions being transverse to the three-brane.
  We derive the physical neutrino mass spectrum and show that the active
neutrino mass and Kaluza-Klein masses have a logarithmic cutoff divergence
related to the zero-size limit of the three-brane in the transverse space. This
translates into a renormalisation group running of the neutrino masses above
the Kaluza-Klein compactification scale coming from classical effects, without
any new non-singlet particles in the spectrum. For compact radii in the eV--MeV
range, relevant for neutrino physics, this scenario predicts running neutrino
masses which could affect, in particular, neutrinoless double beta decay
experiments.
