Matter effects for `just so' oscillations

Abstract

We study the effect of the matter term on the evolution of the solar neutrinos when the neutrino parameters are those of the `just-so' case. The extreme non-adiabatic effects at the edge of the sun reduce the expression for the survival probability in the just-so case to that of the vacuum case. This conclusion is independent of the width of the extreme non-adiabatic region, which is a function of the density profile of the sun beyond $r > 0.9 R_s$. However, in its propagation, neutrino encounters regions of moderate (non-extreme) non-adiabticity. Neutrino traversal through these regions give corrections to the survival probability which are profile dependent.

11 pages including one figure