Z-induced FCNCs and their effects on Neutrino Oscillations

Adding singlet neutrinos to the standard model spectrum in general gives rise to Z-induced flavor-changing neutral currents. We study the impact of these currents on matter-induced neutrino oscillations in the sun and in supernovae. While the effects for solar neutrinos are negligible, dramatic effects are possible for supernova neutrinos.Comment: 23 pages (including 5 eps-figures), Latex; references [29-34] were added to the revised versio