James Cronin coauthored the 1964 discovery of CP violation in neutral kaon decays. Magnetic analysis and spark chambers reconstructed two charged tracks from a long-lived neutral beam. The small two-pion component was incompatible with the simple CP-conserving assignment of that state. A rare decay channel thus tested a fundamental symmetry of the weak interaction.[ref]
Evidence for the 2π Decay of the K₂⁰ Meson by James H. Christenson and others. 1964, apparatus, two-pion reconstruction and CP-symmetry implication
Portrait of James Cronin
. Rungbachduong. CC BY-SA 3.0, via Wikimedia Commons. Source.
