It is shown that intrinsic neutrino flavor violation invariably occurs when
neutrinos are created within the SM augmented by the known massive neutrinos,
with mixing and nondegenerate masses. The effects are very small but much
greater than the naive estimate Δm2/Eν2 or the branching ratio of
indirect flavor violating processes such as μ→eγ within the SM. We
specifically calculate the probability (branching ratio) of pion decay
processes with flavor violation, such as π→μνˉe, showing
nonzero results.Comment: v3: published versio