On the indistinguishibility of Majorana- from Dirac-neutrino propagation   in a stellar medium
  We study, in the framework of the Standard Model, the propagation of (pure) Majorana neutrinos in a typical stellar medium and show that Majorana neutrino matter oscillations are completely indistinguishable from Dirac ones, even if in the case of no family mixing Majorana neutrinos can be distinguished from Dirac ones in the non-relativistic limit. Moreover, if CP violation is present, an effective phase arises in the effective mixing matrix but, due to a symmetry of the Majorana fields, this cannot be univocally determined 
S. Esposito (I.N.F.N. Sezione di Napoli)