Maximal ${\nu }_e\to {\nu }_s$ solution to the solar neutrino problem: just-so, MSW or energy independent?

Abstract

We examine the maximal ${\nu }_e\to {\nu }_s$ solution to the solar neutrino problem. This solution can be motivated by the exact parity model and other theories. The ${\nu }_e$ survival probability exhibits one of three qualitatively different behaviours depending on the value of $\Delta m^2$, viz. approximately energy independent, just-so or MSW. By the last of these we mean an enhanced night-time event rate due to regeneration in the Earth. We study all of these possibilities in the context of the recent SuperKamiokande data.

Comments: minor changes to text and fig.4