Quantum Mechanics of Neutrino Oscillations - Hand Waving for Pedestrians

Abstract

Why Hand Waving? All calculations in books describe oscillations in time. But real experiments don't measure time. Hand waving is used to convert the results of a "gedanken time experiment" to the result of a real experiment measuring oscillations in space. Right hand waving gives the right answer; wrong hand waving gives the wrong answer. Many papers use wrong handwaving to get wrong answers. This talk explains how to do it right and also answers the following questions: 1. A neutrino which is a mixture of two mass eigenstates is emitted with muon in the decay of a pion at rest. This is a a "missing mass experiment" where the muon energy determines the neutrino mass. Why are the two mass states coherent? 2. A neutrino which is a mixture of two mass eigenstates is emitted at time t=0. The two mass eigenstates move with different velocities and arrive at the detector at different times. Why are the two mass states coherent? 3. A neutrino is a mixture of two overlapping wave packets with different masses moving with different velocities. Will the wave packets eventually separate? If yes, when?