Expectation values of flavor-neutrino numbers with respect to neutrino-source hadron states: Neutrino oscillations and decay probabilities

fujii, kanji; toyota, norihito;

On the basis of quantum field theory, we consider a unified description of various processes accompanied by neutrinos, namely, weak decays and oscillation processes. The structures of the expectation values of flavor-neutrino numbers with respect to the neutrino-source hadron state are investigated. Due to the smallness of neutrino masses, we naturally obtain the old (i.e., premixing) formulas of decay probabilities. In addition, it is shown that the oscillation formulas,
similar to the usual ones, are derived irrespectively of the details of neutrino-producing processes.
The derived oscillation formulas are regarded as being the same in form as the usually adopted
ones, except for some simple distinctions.