Universal Seesaw and Radiative Quark Mass Hierarchy

A new approach to the fermion mass problem is suggested. The mass hierarchy is first radiatively generated in a sector of heavy isosinglet fermions and then projected to the visible ones by means of a universal seesaw. In this way flavour-changing phenomena are naturally suppressed. A quantitatively correct picture of quark masses and mixing is obtained. In particular, in contrast to previous approaches, the correct value of the Cabibbo angle can be accommodated without troubles for the perturbation expansion. By fitting the values of the masses of the five known quarks, we find that the natural value of m(t) is in the 100 GeV range.