  We discuss some phenomenological consequences in a scenario where a singlet
Majoron plays the role of dark radiation. We study the interrelations between
neutrino mass generation and the scalar potential arising from this
identification. We find the extra scalar has to be light with a mass at or
below the GeV level. The mixing of this scalar with the Standard Model Higgs
impacts low energy phenomena such as the muonic hydrogen Lamb shift and muon
anomalous magnetic moment. Demanding that the light scalar solves the puzzle in
the muon magnetic moment requires the scalar to be lighter still with mass at
or below the 10 MeV level. The cross-sections for the production of heavy
neutrinos at LHC14 are also given.
