CP VIOLATION IN KL DECAYS

The symmetries C (particle-antiparticle interchange) and P (space inversion) hold for strong and electromagnetic interactions. After the discovery of large C and P violation in the weak interactions, it appeared that the product CP was a good symmetry. In 1964 CP violation was observed in K0 decays at a level given by the parameter ≈ 2.3 × 10−3. A unified treatment of CP violation in K, D, B, and Bs mesons is given in “CP Violation in Meson Decays” by D. Kirkby and Y. Nir in this Review. A more detailed review including a thorough discussion of the experimental techniques used to determine CP violation parameters is given in a book by K. Kleinknecht [1]. Here we give a concise summary of the formalism needed to define the parameters of CP violation in KL decays, and a description of our fits for the best values of these parameters.