  The two-particle wave function of neutrino and antineutrino after the decay
of a Z boson is found as a solution of an initial value problem. The wave
packet of this state involves the coherent superposition of massive neutrinos
and antineutrinos resulting in independent oscillations of their flavor
counterparts. Possible experiments to observe oscillations of a single lepton
or both leptons from the same decay and the three independently emitted pairs
are considered.
