Top-bottom splitting in technicolor with composite scalars

Abstract

We present a model of dynamical electroweak symmetry breaking in which the splitting between the top and bottom quark masses arises naturally. The W and Z masses are produced by a minimal technicolor sector, the top quark mass is given by the exchange of a weak-doublet technicolored scalar, and the other quark and lepton masses are induced by the exchange of a weak-doublet technicolor-singlet scalar. We show that, in the presence of the latter scalar, the vacuum alignment is correct even in the case of SU(2) technicolor. The fit of this model to the electroweak data gives an acceptable agreement (chi-squared = 28 for 20 degrees of freedom). The mass hierarchy between the standard fermions other than top can also be explained in terms of the hierarchy of squared-masses of some additional scalars. We discuss various possibilities for the compositeness of the scalars introduced here.