Within the context of the 't Hooft anomaly matching scheme, some guiding principles for model building are discussed with an eye to low-energy phenomenology. It is argued that Λch(chiral symmetry breaking scale of the global color-flavor group GCF) ≈ ΛMC(metacolor scale) and ΛgCF(unification scale of the gauge subgroup of GCF) ≲ Λch. As illustrations of the method, two composite models are suggested that can give rise to three or four generations of ordinary quarks and leptons without exotic fermions. © 1986.
Li, X., & Marshak, R. E. (1986). Towards a realistic composite model of quarks and leptons. Nuclear Physics, Section B, 268(2), 383–396. https://doi.org/10.1016/0550-3213(86)90160-4