Neutrino oscillations from pion decay in flight

Presented is a field theory treatment of neutrino flavor oscillations in the process p (T)--> (X') + pi(+) --> (mu(+)) + nu (D)--> l(-/+) + (X), where T and D stand for the target and detector, respectively. Without arbitrary wave-packets, it is shown that with the introduction of the experimental operating parameters to constraint the phase space the different limitations of the ''classical'' derivation of the oscillating amplitude are generated. The conditions of the NOMAD experiment performed at CERN are used as a guide line. (C) 1997 Elsevier Science B.V.