Flavour transitions of Dirac-Majorana neutrinos
1 Dipartimento di Scienze Fisiche, Università di Napoli "Federico II'' Mostra d'Oltremare Pad. 19, I-80125 Napoli, Italy and Istituto Nazionale di Fisica Nucleare, Sezione di Napoli, Mostra d'Oltremare Pad. 20, I-80125 Napoli, Italy
Received: 20 February 1998 / Published online: 5 June 1998
From a phenomenological point of view, we study active-active and active-sterile flavour-changing (and flavour-conserving) oscillations of Dirac-Majorana neutrinos both in vacuum and in matter. The general expressions for the transition probabilities in vacuum are reported. We then investigate some interesting consequences following from particular simple forms of the neutrino mass matrices, and for the envisaged scenarios we discuss in detail neutrino propagation in matter. Special emphasis is given to the problem of occurrence of resonant enhancement of active-active and active-sterile neutrino oscillations in a medium. The peculiar novel features related to the Dirac-Majorana nature of neutrinos are particularly pointed out.