FLAVOR-NONDIAGONAL TRANSITIONS OF MASSIVE NEUTRINOS IN AN EXTERNAL-FIELD

Flavor-changing transitions of massive neutrinos induced by the field of a circularly polarized wave are studied within the framework of the Glashow-Weinberg-Salam theory with lepton mixing. The amplitude and p robability of the transition nu(i) --> nu(j) (i not-equal j), taking a ccount of the polarization of the initial and final neutrino, are calc ulated. The transition nu(i) --> nu(j) is compared with the process nu (i) --> nu(j)-gamma in the absence of an external field. It is shown t hat the branching ratio does not depend on the mixing angles or on the masses of the intermediate charged leptons.