NEUTRINOS IN EXTRA DIMENSIONS AND SUPERNOVAE

Models with extra space dimensions naturally provide for the existence of fermions that propagate in them. These are seen in 4D as an infinite tower of sterile neutrinos possibly mixed with the Standard Model ones. We consider the effect of such a mixing in the context of core collapse supernova physics. We show that the potentially dramatic modifications to the supernova evolution (commonly believed to set very strong bounds on the parameters of the extra dimensions) are prevented by a mechanism of feedback, so that much weaker bounds need to be imposed. Nevertheless, the supernova core evolution is significantly modified. We discuss the compatibility with the SN 1987A signal and we analyse the distinctive signatures of the neutrino signal on Earth.