A combined treatment of neutrino decay and neutrino oscillations

Neutrino decay in vacuum has often been considered as an alternative to neu trino oscillations. Because nonzero neutrino masses imply the possibility o f both neutrino decay and neutrino oscillations, we present a model-indepen dent formal treatment of these combined scenarios. For that, we show for th e example of Majoron decay that in many cases decay products are observable and may even oscillate. Furthermore, we construct a minimal scenario in wh ich we study the physical implications of neutrino oscillations with interm ediate decays. (C) 2001 Elsevier Science B.V. All rights reserved.