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

TL;DR

This paper investigates the maximal electron neutrino to sterile neutrino oscillation solution to the solar neutrino problem, analyzing different regimes (energy independent, just-so, MSW) in light of SuperKamiokande data.

Contribution

It provides a comprehensive analysis of the maximal    sterile neutrino solution, classifying the behaviors and comparing them with recent experimental results.

Findings

Identifies three distinct    behaviors based on m^2 values.

Shows compatibility of certain regimes with SuperKamiokande data.

Highlights the potential for Earth regeneration effects in the MSW regime.

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.