Higher extended technicolor representations and fermion generations

Abstract

We investigate an idea for explaining fermion generations in which quarks and charged leptons of different generations arise from extended technicolor (ETC) multiplets transforming according to different representations of the ETC gauge group. Two types of models embodying this idea are constructed and analyzed. Although this mechanism would have the potential, a priori, to provide a new type of explanation for the generational hierarchy and to allow a reduction in the value of N _ETC relative to conventional ETC models, it is disfavored by excessive chiral symmetry, and we show that it is excluded by the fact that in the first type of model the technicolor sector is not asymptotically free, while the second type of model predicts fermions with exotic quantum numbers that are not observed.