Neutrino Oscillations and Energy-Momentum Conservation
  A description of neutrino oscillation phenomena is presented which is based on relativistic quantum mechanics and includes both entangled state and source dependent aspects, unlike both of the conventional approaches which use either equal energies or equal momenta for the different neutrino mass eigenstates. To second order in the neutrino masses, the standard result is recovered thus showing an absence of source dependence to this order. The time dependence of the wavefunction is found to be crucial to recovering the conventional result. An ambiguity appears at fourth order in the neutrino masses which generally leads to source dependence, but the standard formula can be promoted to this order by a plausible convention. 
T. Goldman