Leptonic processes in an ultrastrong magnetic field

The emission of a massive neutral vector particle by a charged lepton in a magnetic field H and the decay of a resting muon in which an electron is produced in the ground state are considered. The probabilities of these processes are calculated. It is shown that these processes may become most probable in the range of ultrastrong fields $H ≥H_{0}=(m^{2}c^{3})/(e_{0}ħ)= 4,41∙10^{13}$ G.