Particle Physics Seminar

Interference between $\nu$'s with different masses is not observable in an ideal detector measuring energies and momenta of the detector nucleon and emitted lepton. The $\nu$ mass is
bobservable. No oscillations between $\nu$ states with different masses occur
regardless of the $\nu$ production process or any entanglement. Oscillations are
observable only in a non-ideal detector that cannot measure everything. In realistic detectors
incident $\nu$'s with same energy and different momenta
charge exchange with nucleon, produce same nucleon-charged-lepton final state, leave no trace of initial $\nu$ momentum and are coherent.
Momentum transfer out of the system without energy loss analogous to recoilless photon emission in M\"ossbauer effect explains interferences: (1) producing $\nu$ oscillations and
(2)forbidding electron production in $\nu$ detectors after $\pi \rightarrow \mu \nu$ decay.
Interference between $\nu$ states with differentenergies described in textbooks is not observable in realistic experiments.
A $\nu$ mass eigenstate can produce either an electron or a muon.
Canceling the electron amplitude requires interference between amplitudes
from different entering $\nu$ mass eigenstates with different four-momenta.
Interactions needed to keep nucleon inside massive detector of finite size can transfer momentum with negligible energy transfer. This energy-momentum asymmetry is simple only in
laboratory system and not easily treated by relativistic quantum field theory.
Condensed matter physics, the M\"ossbauer effect and Dicke Superradiance are needed.
$\nu$ detection is a ``two slit" or ``which-path" experiment in momentum space.
Contributions via different paths are coherent.