ABSTRACT
Charge conjugation changes the particles in Figure 12.1 into antiparticles, and vice versa. Parity transformation changes the spin (le into right, and vice versa). With a CP transformation, Figure 12.1a and b is interchanged. us, if CP were a good symmetry, then the couplings in the two gures should coincide and Vud should coincide with V*ud. Because the arrows corresponding to Vud and V*ud have opposite phases, these couplings can only coincide if their phases vanish. at is, if CP were conserved, then Vud would be an ordinary real number. Couplings that are not real numbers are the only source of CP violation in the standard model.
