Neutrino decay to electron and W boson in a superstrong magnetic field in the Early Universe

An intense electromagnetic field makes possible the process of the neutrino decay into electron and W boson that is kinematically forbidden in a vacuum. The exact formula for the probability of ultra high energy neutrino decay in a superstrong magnetic field via the representation for the propagators of the charged particles expanded as sums over Landau levels is derived. The obtained function clarifies previously known approximate formula. The neutrino mean free path is estimated. It is shown, that the resonance peaks present in the decay width for certain neutrino energies correspond to the electron and the W boson creation at specific Landau levels. Some interesting possible manifestations of the process in the conditions of the Early Universe are briefly discussed