The existence of bulk sterile neutrinos in theories with large extra
dimensions can naturally explain small 4-dimensional Dirac masses for the
active neutrinos. We study a model with 3 bulk neutrinos and derive various
constraints on the size of the extra dimensions from neutrino oscillation
experiments. Our analysis includes recent solar and atmospheric data from SNO
and Super-Kamiokande, respectively, as well as various reactor and accelerator
experiments. In addition, we comment on possible extensions of the model that
could accommodate the LSND results, using natural parameters only. Our most
conservative bound, obtained from the atmospheric data in the hierarchical mass
scheme, constrains the largest extra dimension to have a radius R < 0.82
microns. Thus, in the context of the model studied here, future gravitational
experiments are unlikely to observe the effects of extra dimensions.Comment: 26 page
