Radiative neutrino decays in very strong magnetic fields

The radiative decay $\nu_H \to \nu_L + \gamma$ of massive neutrinos is analyzed in the framework of the standard model with lepton mixing for very strong magnetic fields $B\gg B_{cr} = m_e^2/e \sim 4.14 \times 10^{13}$G. The analysis is based on the approximate decay amplitude obtained by Gvozdev et al. Numerical results as well as analytical approximations for the decay rate are obtained for energies of the initial neutrino below and {\em above} the electron-positron pair creation threshold $2m_e$.