The paper by Makoto Kobayashi and Toshihide Maskawa explores the problem of CP violation within a renormalizable theory of weak interaction. They conclude that realistic models of CP violation in the quartet scheme without introducing new fields are not possible. The authors discuss various models and scenarios to incorporate CP violation, including: 1. **Quartet Model**: The quartet model is considered, with a focus on the charge assignments and gauge groups. They analyze different representations of the quartet field under \(SU_{\text{weak}}(2)\) and find that certain cases (e.g., \((B, C)\), \((C, B)\), and \((C, C)\)) are not viable due to experimental constraints on strangeness-changing neutral currents. 2. **CP-Violating Interactions**: They explore ways to introduce CP violation through additional scalar doublet fields or strong interaction mediating scalar fields. These interactions can violate CP conservation without requiring new fields. 3. **6-plet Model**: Another interesting model is the 6-plet model, where the charges are decomposed into \(SU_{\text{weak}}(2)\) multiplets. This model allows for CP-violating effects in non-leptonic processes and semi-leptonic decays of neutral strange mesons. 4. **Other Schemes**: The authors also consider other underlying gauge groups and scalar fields, such as Georgi and Glashow's model, which can incorporate CP violation without introducing additional fields. The paper provides a detailed analysis of the constraints and possibilities for CP violation in the context of the renormalizable theory of weak interaction.The paper by Makoto Kobayashi and Toshihide Maskawa explores the problem of CP violation within a renormalizable theory of weak interaction. They conclude that realistic models of CP violation in the quartet scheme without introducing new fields are not possible. The authors discuss various models and scenarios to incorporate CP violation, including: 1. **Quartet Model**: The quartet model is considered, with a focus on the charge assignments and gauge groups. They analyze different representations of the quartet field under \(SU_{\text{weak}}(2)\) and find that certain cases (e.g., \((B, C)\), \((C, B)\), and \((C, C)\)) are not viable due to experimental constraints on strangeness-changing neutral currents. 2. **CP-Violating Interactions**: They explore ways to introduce CP violation through additional scalar doublet fields or strong interaction mediating scalar fields. These interactions can violate CP conservation without requiring new fields. 3. **6-plet Model**: Another interesting model is the 6-plet model, where the charges are decomposed into \(SU_{\text{weak}}(2)\) multiplets. This model allows for CP-violating effects in non-leptonic processes and semi-leptonic decays of neutral strange mesons. 4. **Other Schemes**: The authors also consider other underlying gauge groups and scalar fields, such as Georgi and Glashow's model, which can incorporate CP violation without introducing additional fields. The paper provides a detailed analysis of the constraints and possibilities for CP violation in the context of the renormalizable theory of weak interaction.