We discuss neutrino oscillations in the framework of the quantum field theory without introducing the concept of neutrino weak eigenstates. The external particles are described by wave packets and the different mass eigenstate neutrinos propagate between the production and detection interactions, which are macroscopically localized in space-time. The time-averaged cross section, which is the measurable quantity in the usual experimental setting, is calculated. It is shown that only in the extremely relativistic limit can the usual quantum mechanical oscillation probability be factored out of the cross section.

• Received 17 May 1993

DOI:https://doi.org/10.1103/PhysRevD.48.4310