Neutrino survival probabilities in magnetic fields - art. no. 053009

We show that, for Majorana neutrinos propagating in a constant magnetic fie ld, the flavor survival probabilities for left-handed neutrinos are the sam e as for right-handed neutrinos, i.e., P-M(nu(alpha L) --> nu(alpha L)) = P -M (nu(alpha R) --> nu(alpha R)), where alpha = e, mu, tau, whereas in the Dirac case the corresponding probabilities P-D(nu(alpha L) --> nu(alpha L)) and P-D(<(nu)over bar>R --> <(nu)over bar>(alpha R)) are in general differ ent. This might lead to a novel way to search for the nature of neutrinos. We also discuss how this relation for Majorana neutrinos gets modified when the magnetic field is not constant. However, if matter effects become impo rtant, the relation does not hold anymore.