Solar neutrino oscillation from large extra dimensions

A plausible explanation for the existence of additional light sterile neutr inos is that they correspond to modulini, fermionic partners of moduli, whi ch propagate in new large dimensions. We discuss the phenomenological impli cations of such states and show that solar neutrino oscillation is well des cribed by small angle MSW oscillation to the tower of Kaluza-Klein states a ssociated with the modulini. In the optimal case the recoil electron energy spectrum agrees precisely with the measured one, in contrast to the single sterile neutrino case which is disfavoured. We also consider how all oscil lation phenomena can be explained in a model including bulk neutrino states . In particular, we show that a naturally maximal mixing for atmospheric ne utrinos can be easily obtained. (C) 2000 Published by Elsevier Science B.V.