Violation of matter-antimatter symmetry

A small matter-antimatter asymmetry of the weak force was experimentally established. This CP violation may be related to the small excess of matter from the big bang. The nature of CP violation in the K⁰ system has been clarified after 35 years of experimentation: it is due to a small part of the weak interaction (“milliweak interaction”). A non-trivial phase in the weak quark mixing matrix generates “direct CP violation” in the weak Hamiltonian. The experiments demonstrating direct CP violation are discussed.