Unified field-theoretical description of flavor and chiral oscillations

Since chirality is not conserved during free propagation, massive fermions produced through weak interactions experience chiral oscillations. For analogous reasons, neutrinos also exhibit flavor oscillations. These phenomena have been extensively studied – both individually and within a unified framework – using the first quantization approach, but only separately in the context of quantum field theory. In this work, we address this gap by developing a quantum field theory treatment of flavor-chiral oscillations. Focusing on the case of two-flavor mixing, we compute the expectation values of the (non-conserved) chiral-flavor charges and recover the oscillation formulas obtained in the first quantization formalism. The chiral-flavor charges are diagonalized via Bogoliubov transformations in both the chiral and flavor sectors. Such transformations reveal a non-trivial structure of the chiral-flavor vacuum, which consists of a condensate of particles with definite masses and helicities.