Maximal $ν_e \to ν_s$ solution to the solar neutrino problem: just-so, MSW or energy independent?

Abstract

We examine the maximal $ν_e \to ν_s$ solution to the solar neutrino problem. This solution can be motivated by the exact parity model and other theories. The $ν_e$ survival probability exhibits one of three qualitatively different behaviours depending on the value of $Δm^2$, 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.

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