The fermion mass matrices near a fixed point

The structure of the fermion mass matrices is investigated in the neighbourhood of an infrared fixed point with special emphasis on the mixing angles which determine the charged current couplings. We find that it is necessary to introduce a fourth generation of quarks whose masses are predicted. The mass of the top quark is close to 35 GeV. The solution for a two family problem is found, which predicts very small charged current couplings of the very heavy to the lighter quarks. (orig.)