The radiative decay of ultrarelativistic massive neutrino νi​→νj​γ is investigated in electromagnetic fields in the framework of the
Standard Model with lepton mixing. Estimates of the decay probability and
``decay cross-section'' for accelerator neutrinos of high energies in the
electric field of nucleus permit one to discuss the general possibility of
carrying out the neutrino experiment. Such an experiment could give unique
information on mixing angles in the lepton sector of the Standard Model which
would be almost independent of the specific neutrino masses.Comment: 6 pages, LaTeX, Talk given by L.A.Vassilevskaya at the XXXth
Rencontres de Moriond, Electroweak Interactions and Unified Theories, Les
Arcs, Savoie, France, March 11-18, 199