RADIATIVE DECAY OF THE MASSIVE NEUTRINO IN EXTERNAL ELECTROMAGNETIC-FIELDS

The radiative decay of the massive neutrino nu(i)-->nu(j) gamma is inv estigated in the framework of the standard model in external electroma gnetic fields of various configurations: constant crossed field, const ant uniform magnetic field, plane monochromatic wave's held. The effec t of significant enhancement of the neutrino decay probability by the external field (electromagnetic catalysis) is discussed. An especially strong enhancement occurs in the case of the ultrarelativistic neutri no decay, since in this case the decay probability does not contain su ppression caused by the smallness of the decaying neutrino mass. The u ltrarelativistic neutrino decay catalysis is significant even in a rel atively weak external field (F/F-e much less than 1, where F-e is the critical Schwinger value). The expression for the photon splitting pro bability into a neutrino pair gamma-->nu(i)<(nu)over bar (j)> in the w ave field is given. The estimations of a number of gamma quanta produc ed in a volume filled with an electromagnetic field and the neutrino l ifetime in a strong magnetic field are presented.