Coherence in neutrino oscillations

Abstract

The theory of neutrino oscillations has turned out to be the most reasonable explanation to the observed violations in lepton number conservation of solar and atmospheric neutrino fluxes. A derivation of the most important results of this theory is first given using a plane wave treatment and subsequently using a three-dimensional shape-independent wave packet approach. Both methods give the same oscillation patterns, but only the latter one serves as a decent starting point for analyzing coherence in neutrino oscillations.

A numerical analysis of the oscillation patterns on various distance scales is also given to graphically illustrate the phenomenon of neutrino oscillation and loss of coherence in it.

Several coherence conditions related to wave packet separation and the uncertainties of energy and momentum in the mass states produced in a weak charged current reaction are derived. In addition, a new limit is obtained for neutrino flux, beyond which the oscillation pattern may be washed out due to the overlap of the wave packets describing neutrinos originating from different reactions. Whether or not any phenomena will take place in the case of very high flux remains uncertain, because the flux limit is beyond the scope of any modern neutrino experiment.