Aspects of dynamical electroweak symmetry breaking

In technicolor models it has recently been suggested that dynamics at scales much higher than the electroweak scale can play a significant role in electroweak symmetry breaking, and that these effects can lead to a heavy top quark while alleviating the flavor changing neutral current problems endemic to extended technicolor theories. In this paper we formulate the conditions necessary for this hierarchy to occur. We show that, if extended technicolor interactions are to play a role in electroweak symmetry breaking and in particular if they are to enhance fermion masses above their values in the usual weak extended technicolor scenario, then the chiral symmetry breaking phase transition must be second order. We also show that the effective low-energy theory below the ETC scale must include both technicolor and a light composite scalar with large couplings to ordinary fermions and technifermions.