Medium effects in string-dilaton-induced neutrino oscillations

Abstract

We consider an unconventional way to interpret the current data on solar neutrino oscillations as derived recently by Halprin and Leung from a string model based on the existence of the string dilaton field which remains massless in the low-energy world. The equivalence principle violation entailed by the existence of a massless dilaton may then produce neutrino oscillations even for neutrinos that are degenerate in mass. Here we calculate the medium-induced mass squared difference for solar and atmospheric neutrinos, which is due to their coherent interactions with the cosmic neutrino background and with solar plasma constituents. We show that this difference can naturally be large enough to satisfy the known experimental limits on the oscillatory solutions of the solar as well as atmospheric neutrino problem.