Solar neutrinos: Oscillations or No-oscillations?

TL;DR

This paper discusses whether solar neutrino observations are better explained by neutrino oscillations or adiabatic flavor conversion, highlighting the nuances and implications of both phenomena for neutrino mass understanding.

Contribution

It provides a pedagogical comparison of neutrino oscillations and adiabatic conversion, clarifying their roles in solar neutrino experiments and their implications for neutrino mass.

Findings

Oscillations are mainly relevant for Earth-based regeneration effects.

Adiabatic conversion explains solar neutrino flavor changes without requiring neutrino mass.

Further studies are needed to confirm neutrino masses from solar neutrino data.

Abstract

The Nobel prize in physics 2015 has been awarded "... for the discovery of neutrino oscillations which show that neutrinos have mass". While SuperKamiokande (SK), indeed, has discovered oscillations, SNO observed effect of the adiabatic (almost non-oscillatory) flavor conversion of neutrinos in the matter of the Sun. Oscillations are irrelevant for solar neutrinos apart from small $\nu_e$ regeneration inside the Earth. Both oscillations and adiabatic conversion do not imply masses uniquely and further studies were required to show that non-zero neutrino masses are behind the SNO results. Phenomena of oscillations (phase effect) and adiabatic conversion (the MSW effect driven by the change of mixing in matter) are described in pedagogical way.