Generation model of particle physics and the parity of the neutral pion

The chapter emphasizes that the Generation Model is obtained from the StandardModel of particle physics essentially by interchanging the roles of the mass eigenstate and weak eigenstate quarks. In the Generation Model the mass eigenstate quarks of the same generation form weak isospin doublets analogous to the mass eigenstate leptons of the same generation while the weak eigenstate quarks form the constituents of hadrons. This allows a simpler and unified classification scheme in terms of only three conserved additive quantum numbers for both leptons and quarks. This unified classification scheme of the GenerationModel makes feasible a composite model of the leptons and quarks, which predicts that the weak eigenstate quarks are mixed-parity states. In the Standard Model pions have parity P = -1 and the chapter describes that this value of the parity of pions led to the overthrow of both parity conservation and CP conservation in weak interactions. In the Generation Model pions exist in mixed-parity states leading to an understanding of the apparent CP violation observed by Christenson et al. in the decay of the long-lived neutral kaon.