ON WEAK ISOSPIN VIOLATION DUE TO DYNAMICALLY GENERATED FERMION MASS

The effects of large isospin violation due to fermion mass on the electroweak sector is investigated by estimating DELTA-rho, which should experimentally be less than 0.01. We estimate in the dynamical Higgs model, using the Pagels-Stroker approximation. Then the form of the dynamical mass function SIGMA(x = p(E)2) plays an essential role. We make the evaluation dividing three cases, (1) hard mass (SIGMA = m), (2) soft mass (SIGMA = m2/square-root x), and (3) very soft mass (SIGMA = m3/x). In the case (1) our result coincides with that usual calculation of the rho-parameter when the cutoff LAMBDA --> infinity, as expected. In the case (2) DELTA-rho < 0.01 requires 0.8m(U) < m(D) (less-than-or-equal-to m(U)). In the case (3) we can get even rho = 1, if we are allowed to extrapolate-SIGMA to the energy region.