Fermion mass hierarchies and small mixing angles from extra dimensions - art. no. 113017

In this paper we study renormalization-group evolutions of Yukawa matrices enhanced by Kaluza-Klein excited modes and analyze their infrared fixed-poi nt structure. We derive the necessary conditions to obtain hierarchies betw een generations on the fixed point. These conditions restrict how the field s in the models can extend to higher dimensions. Several specific mechanism s to realize the conditions are presented. We also take into account the ge neration mixing effects and find a scenario where the mixing angles become small at low energy even with large initial values at a high-energy scale. A toy model is shown to lead to realistic quark mass matrices.