Terrestrial Neutrino Oscillations Illustrated

TL;DR

This paper discusses atmospheric neutrino observations indicating neutrino mass and oscillations, emphasizing the importance of measuring mixing angles through current and future experiments.

Contribution

It provides a qualitative overview of how two neutrino mixing angles affect observable phenomena in atmospheric neutrino oscillations.

Findings

Evidence for neutrino mass and oscillation from atmospheric data

Compatibility with maximal mu-tau mixing, not mu-e mixing

Framework for measuring two mixing angles in future experiments

Abstract

Observations of atmospheric neutrinos offer compelling evidence that neutrinos have mass and do oscillate. Preliminary data are compatible with maximal $\nu_\mu$--$\nu_\tau$ mixing, but not with pure $\nu_\mu$--$\nu_e$ mixing. In a general three-family scenario with just one relevant squared-mass difference, atmospheric neutrino oscillations involve two mixing angles. The special cases mentioned above are not favored by convincing theoretical arguments. As more precise data are accumulated, both at Superkamiokande and at proposed or ongoing long-baseline experiments, it will become feasible and desirable to measure both angles. To this end, we offer a brief portfolio of illustrations from which the qualitative effects of the two mixing angles on various observable quantities can be discerned.