Quark masses and their hierarchies

Electroweak symmetry breaking is attributed to dynamical generation of quark masses. Quarksq (and leptonsl) are assumed to be produced by hypercolor confinement of preons at an intermediate scaleΛ _hc. Hierarchies observed in theq mass spectra can be explained by a BCS mechanism if the color interaction is enough asymptotically free and if residual ones emerging by the confinement are medium strong. The former assumption claims thatN≦4, whereN is the family number ofq andl. Dynamical equations to determineq masses and mixings are given, but they require knowledge on the physics atΛ _hc. A phenomenological approach is also made on the basis of anSU(7)×SU(7) chiral preon model withN=4. The mass ratiom _t/mb is related to (m _c/m _s)^ηB withη _B?1.1 andm _t'/mb' to (m _u/m _d)^ηA withη _A?1.4. In this scheme the fourth down quark is the heaviest (～ 110 GeV) and contributes dominantly toF ², whereF is the Fermi scale.