Fermion masses, mixings and proton decay in a Randall–Sundrum model

We consider a Randall–Sundrum model in which the Standard Model fermions and gauge bosons correspond to bulk fields. We show how the observed charged fermion masses and CKM mixings can be explained, without introducing hierarchical Yukawa couplings. We then study the impact on the mass scales associated with non-renormalizable operators responsible for proton decay, neutrino masses, and flavor changing neutral currents. Although mass scales as high as 1011–1012 GeV are in principle possible, dimensionless couplings of order 10−8 are still needed to adequately suppress proton decay. Large neutrino mixings seem to require new physics beyond the Standard Model.