Neutrino Mass, Mixing, and Flavor Change

Abstract

As outlined in this chapter, neutrino flavor change, either in vacuo or in matter, implies neutrino mass and mixing. Thus, the very strong evidence for flavor change makes a compelling case that neutrinos have nonzero masses. Owing to the possibility -- unique to neutrinos -- of Majorana mass terms, the physics underlying neutrino mass may be quite di.erent from that underlying the masses of the quarks and charged leptons. In addition, if Majorana mass terms are present, the neutrinos are Majorana particles, making them quite different from the other fundamental fermions.