Invisible Axions and Light Neutrinos—are They Connected?

Physical arguments involving the solar neutrino problem are given which connect the scale of U (1) PQ breakdown with that of the spontaneous breakdown of lepton number. In the simplest model, the Majoron transmutes itself into the invisible axion as a soft symmetry breaking parameter is turned on. Some consequences of this idea are discussed. These include a suggestion that the origin of the baryon symmetry of the Universe is connected with an induced lepton number asymmetry produced at temperatures of order V PQ and the possibility that ν μ →ν τ oscillations may be observable at accelerators.