Natural Neutrino Dark Energy
  A new class of neutrino dark energy models is presented. The new models are
characterized by the lack of exotic particles or couplings that violate the
standard model symmetry. It is shown that these models lead to several concrete
predictions for the dark energy equation of state, as well as possible effects
on the cosmic structure formation. These predictions, can be verified (or
disproved) with future experiments. At this point, the strongest constraints on
these models are obtained from big bang nucleosynthesis, and lead to new bounds
on the mass of the lightest neutrino.
