Study of an Alternate Mechanism for the Origin of Fermion Generations

TL;DR

This paper explores a novel mechanism for the origin of fermion generations in technicolor theories, proposing different ETC representations for different generations, but finds it incompatible with simple models due to non-asymptotic freedom and exotic fermions.

Contribution

It introduces an alternative idea for fermion generation origins using varied ETC representations and evaluates its viability in simple models.

Findings

The mechanism is incompatible with simple models due to non-asymptotic freedom.

Exotic fermions with unobserved quantum numbers appear in the models.

Potential reduction in the ETC group size is not feasible with this approach.

Abstract

In usual extended technicolor (ETC) theories based on the group ${\rm{SU}(N_{ETC}})_{ETC}$, the quarks of charge 2/3 and -1/3 and the charged leptons of all generations arise from ETC fermion multiplets transforming according to the fundamental representation. Here we investigate a different idea for the origin of SM fermion generations, in which quarks and charged leptons of different generations arise from ETC fermions transforming according to different representations of ${\rm{SU}(N_{ETC}})_{ETC}$. Although this mechanism would have the potential, {\it a priori}, to allow a reduction in the value of $N_{ETC}$ relative to conventional ETC models, we show that, at least in simple models, it is excluded by the fact that the technicolor sector is not asymptotically free or by the appearance of fermions with exotic quantum numbers which are not observed.