  A natural scenario for the generation of neutrino masses is the see-saw
mechanism, in which a large right-handed neutrino mass makes the left-handed
neutrinos light. We review a special case when the Majorana masses originate
from spontaneous breaking of a global U(1)XU(1) symmetry. The interactions of
the right-handed with the left-handed neutrinos at the electorweak scale
further break the global symmetry giving mass to one pseudo Nambu-Goldstone
boson (pNGB). The pNGB can then generate a long-range force. Leptogenesis
occurs through decays of heavy neutrinos into the light ones and Higgs
particles. The pNGB can become the acceleron field and the neutrino masses vary
with the value of the scalar field. The talk is a brief preview of the results
in reference [11].
