Gravitational Interaction of Neutrinos in Models with Large Extra Dimensions

In the framework of large extra-dimension models, oscillations between neutrinos on the brane and those in the bulk can be affected by the un-suppressed gravitational interaction. For solar neutrinos, oscillation to sterile states is substantially modified if the size of the extra dimension is of the order of current bounds and the fundamental scale is near the electroweak one. The physics of ultra-high energy neutrinos in cosmic-ray physics is modified even for much larger fundamental scales. These examples are instances of a more general property of fields allowed to propagate in different portions of space-time, for which the reduction to four dimensions leads to an effective violation of the principle of equivalence