Unified gauge theories with right-handed currents and heavy fermions

Gauge models with heavy fermions and right-handed currents are discussed based on the gauge groups ${SU(2)}A×{}U(1)×{}{SU(4)}^{{'}},{SU(2)}A×{}{SU(2)}B×{}{SU(4)}^{{'}}, and SU(4) × SU{(4)}^{{'}}$ and are constructed so as to lead to the ${Δ}I=1/2rule. SU(4) × SU{(4)}^{{'}}$ is advocated as the ultimate unifying gauge group of nature, and it is shown how at various stages of spontaneous breakdown both the ${SU(2)}A×{}{SU(2)}B×{}{SU(4)}^{{'}}$ and ${SU(2)}A×{}U(1)×{}{SU(4)}^{{'}}$ groups manifest themselves. We also show that $CP$ violation takes an interesting complexion in these models and leads to exactly the relations ${{η}}_{+{-}}{}{{η}}₀₀$ in ${K}L{→}2{π}$ decays. Furthermore, we show that the magnitude of $CP$ violation is related to gauge interactions that violate the heavy quark degeneracy.