  Considering neutrinos as time-like leptons one may estimate the three-body
decay probability of muon neutrinos in long base-line accelerator experiments.
In the extreme assumption of time-space symmetry the absolute value of the
transcendent mass of a muon neutrino is equal to the rest mass of its bradyon
partner which is, however, strongly suppressed in measurements using the weak
interaction. This decay, neglecting small oscillations or other effects, leads
to a strong dependence of the effect on the base-line distance. As a result,
few hundred kilometre long baseline experiments might hardly see muon-like
events. Total rates of electron-like events from three-body decay are
calculated for K2K, MINOS and ICARUS. Shorter base-line experiments able to see
clearly the effect of muon neutrino decay are very promissing component of long
base-line projects.
