MSW-Like Enhancements Without Matter

Abstract

We study the effects of a scalar field, coupled only to neutrinos, on oscillations among weak interaction current eigenstates. The effect of a real scalar field appears as effective masses for the neutrino mass eigenstates, the same for [Formula: see text] as for ν. Under some conditions, this can lead to a vanishing of δ m2, which maximizes mixing independently of the vacuum mixing angles, as in the MSW effect. We discuss some examples and show that it is possible to resolve an apparent discrepancy in spectra required by r-process nucleosynthesis in the mantles of supernovae and by solar neutrino solutions.