Hello everyone! I've a question regarding the neutrino masses. When neutrinos interact they must do so in a specific flavour (e.g. e, μ,τ) and if we go to find out what their flavour is at the interaction we get a specific answer. However, it is not clear to me what we would find out if we were, hypothetically, to directly measure their mass at the interaction. Let's assume we know the masses of the three mass eigenstates (and let's restrict ourselves to the 3 flavours scenario). If I were to measure the mass of electron neutrinos emitted by β decays would I find a single peak centred at the linear combination (given by the elements of the PMNS matrix) of the three masses values or three peaks centred on the values of the three mass eigenstates?