Democratic Mass Matrices Induced by Strong Gauge Dynamics and Large Mixing Angles for Leptons

We consider dynamical realization of the democratic type Yukawa couplingmatrices as the Pendelton-Ross infrared fixed points.?Such fixed points of theYukawa couplings become possible by introducing many Higgs fields, which aremade superheavy but one massless mode. Explicitly, we consider a stronglycoupled GUT based on $SU(5) \times SU(5)$, where rapid convergence to theinfrared fixed point generates sufficiently large mass hierarchy for quarks andleptons. Especially, it is found that the remarkable difference between mixingangles in the quark and lepton sectors may be explained as a simple dynamicalconsequence. We also discuss a possible scenario leading to the realistic massspectra and mixing angles for quarks and leptons. In this scheme, the Yukawacouplings not only for top but also for bottom appear close to theirquasi-fixed points at low energy and, therefore, $\tan \beta$ should be large.Comment: 25 pages, 5 figure