Massless neutrino oscillations

Quantum dynamical semigroups provide a general framework for studying the evolution of open systems. Neutrino propagation both in vacuum and in matter can be analyzed using these techniques: They allow a consistent treatment of nonstandard, dissipative effects that can alter the pattern of neutrino oscillations. In particular, initially massless neutrinos can give rise to a nonvanishing flavor transition probability, involving in addition the Majorana CP-violating mixing phase.