Effects of Gauge Interactions on Fermion Masses in Models with Fermion Wavefunctions Separated in Higher Dimensions

We consider models that generate hierarchies via the separation of fermion wavefunctions in higher-dimensional spaces. We calculate the effects of gauge interactions between fermions and show that these are important and could help to explain (i) why the heaviest known fermion is a charge 2/3 quark, rather than a charge -1/3 quark or a lepton, (ii) why this fermion has a mass $m_t$ comparable to the electroweak symmetry breaking scale $M_{ew}$, (iii) the patterns $m_t >> m_b > m_\tau$ and $m_c >> m_s > m_\mu$, and (iv) the smallness of neutrino masses.