Radiative neutrino decays in very strong magnetic fields

The radiative decay νh → νl + γ of massive neutrinos is analyzed in the framework of the standard model with lepton mixing for very strong magnetic fields B ⪢ Bcr = me2e ∼ 4.14 × 1013G. 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 above the electron-positron pair creation threshold 2me.