DOWN-SECTOR QUARK MASSES AND FLAVOR MIXING RADIATIVELY GENERATED FROM THE UP SECTOR

We present a model of quark mass generation where the observed intergeneration mass hierarchy, large ratio m(t)2/m(b)2 much greater than 1, and flavor mixing can all arise naturally. The basic assumption is that only the charge 2/3 quarks (u(i); i = 1,2,3) couple to heavy fermions F by emission and reabsorption of bosons S. The generation-index dependence of the shape of the form factors at these SFu(i)BAR couplings is responsible for the up-sector mass hierarchy. The W+/- gauge bosons are assumed to have a generation-index-independent anomalous-magnetic-moment-type correction to the standard V - A coupling to quarks. This correction enables the charge -1/3 quarks to acquire masses by coupling to the up-sector charge 2/3 quarks, which provides a natural explanation for m(t)2 much greater than m(b)2. Because the charge 2/3 quark self-energy matrix is probed here at a non-negligible momentum, the down-sector mass matrix turns out to be significantly different from the up-sector mass matrix, thus producing naturally smaller intergeneration mass ratios as well as flavor mixing and CP violation if the form factors are complex. In order to exhibit the remarkable properties of the above scheme, we use a concrete model for the form factors. We find for the particular scenarios M(F) much greater than LAMBDA or M(F) much less than LAMBDA (where LAMBDA is a characteristic mass scale common to all form factors) simple analytical expressions for the mass matrices. Excellent 4 to 6 parameter fits to the 10 observables in the quark sector are obtained. All dimensionless input parameters are of order 1 and do not require fine-tuning. An interesting scenario within our scheme with top-driven SU(2)L x U(1)Y breaking as well as some possible extensions of the model to include mass generation for leptons are briefly discussed.