The radiative decay of a high energy neutrino in the Coulomb field of a nucleus

In the framework of the Standard Model with lepton mixing the radiative decay ${\nu }_i\to {\nu }_j\gamma$ of a neutrino of high ($E_\nu \sim 100 , GeV$)andsuper-high($E_\nu \ge 1 , TeV$) energy is investigated in the Coulomb field of a nucleus. Estimates of the decay probability and ``decay cross-section’’ for neutrinos of these energies in the electric field of a nucleus permit one to discuss the general possibility of carrying out a neutrino experiment, subject to the condition of availability in the future of a beam of neutrinos of these high energies. Such an experiment could give unique information on mixing angles in the lepton sector of the Standard Model which would be independent of the specific neutrino masses if only the threshold factor ($1-m_j^4\mathrm{/}{m}_i^4$) was not close to zero. (Published in Phys.Lett.B 323 (1994) 179).