On Mikheyev-Smirnov-Wolfenstein Resonance Widths

The aim of the present paper is the evaluation of the resonance half-widths of the first maximum for the probability of the total neutrino conversion in a medium. We consider the simplest case of two-neutrino mixing in matter with a constant refraction length. The results can be applied, for example, to studies of neutrino oscillations in the Earth's mantle and elsewhere.