On Neutrino Flavor States

Understand

We review the issues associated with the construction of neutrino flavor states.

• We then provide a consistent proof that the flavor states are approximately well-defined only if neutrinos are ultra-relativistic or the mass differences are negligible compared to energy.
• However, we show that weak interactions can be consistently described by only neutrino mass eigenstates.
• Meanwhile, the second quantization of neutrino flavor fields generally has no physical relevance as their masses are indefinite.