blogwaffe

.neutrinos have mass because of off diagonal terms in the total hamiltonian. .freaking amazing. .electron, muon andtau neutrinos are eigenstates of the weak interaction, but not of the total hamiltonian. .thus, the three states are coupled and oscillate in time between oneanother. .equivalently, you can write eigenstates of the total hamiltionian which are mixed states of the electron, muon and tau neutrinos. .these “mixed”states (in some sense more “pure” than their “constituents”), have well defined mass. .so the original neutrinos must too. .it’s just hard to see since we’reused to looking at things in the electron, muon and taun neutrino basis instead of the “mixed” one (plus defining mass requires arguing some semantics). !mixingimplies mass! .now someone just needs to find how much.