Neutrino mass physics

It is shown that, even if right-handed currents exist, the observation of anti ν → ν oscillation would imply not only that neutrinos are their own antiparticles but also that they have mass. If neutrinos are their own antiparticles, then there can be large CP-violating effects in the leptonic sector even if only two of the lepton generations mix appreciably. However, the nature of the CP-violating signals can be constrained by CPT invariance. In general, neutrinos can have transition electromagnetic dipole moments, and, if they are not their own antiparticles, non-transition moments as well. The role of neutrino-electron scattering in bounding these moments, and the implications for radiative neutrino decay, and for the solar neutrino flux, are discussed. (orig.)