Colliding‐beam data offer evidence for charmed particle

Probably the most convincing evidence for charm yet produced is a new resonance found at SLAC in electron–positron interactions. The particle, of mass $1865±15 MeV,$ decays into hadrons—either into one kaon and one pion or one kaon and three pions. Many believe that the new particle consists of a bound state of a charmed quark and an uncharmed quark so that it has a net charm. Skeptics of the charm hypothesis would be more convinced if electron–positron annihilists would also observe lepton production, as the charm theory predicts.