  Standard Model singlet neutrinos propagating in extra dimensions induce small
Dirac neutrino masses. While it seems rather unlikely that their Kaluza-Klein
excitations directly participate in the observed neutrino oscillations, their
virtual exchange may lead to detectable signatures in future neutrino
experiments and in rare charged lepton processes. We show how these effects can
be described by specific dimension-six effective operators and discuss their
experimental signals.
