Flavor neutrinos as unstable particles: an interaction picture view

Abstract: This paper reviews the similarities in the behavior of unstable particles and oscillating neutrinos using perturbation theory within the interaction picture of quantum field theory. We begin by examining how decaying systems are studied in the interaction picture and then demonstrate how similar calculations can be performed to determine the transition probabilities for flavor oscillations. Notably, the expressions for neutrino oscillations and particle decays are identical in the short-time range. Furthermore, we show that the flavor oscillation formula derived through this method matches, within the adopted approximation, the one obtained using the flavor Fock space approach.