Matter‐antimatter asymmetry found in intermediate interaction

The symmetry of matter and antimatter in electromagnetic interactions is seriously in doubt. An experiment on the decay of the $η0$ meson into a $π+,$ $π−$ and $π0$ shows that, on the average, the $π+$ comes off with more energy than the $π−.$ This result, reported in the 27 June issue of Physical Review Letters, implies that charge‐conjugation invariance, believed valid in strong interactions, does not hold in interactions that have less strength. The discovery of this matter‐antimatter asymmetry has intrigued such diverse beings as particle physicists, newspaper reporters and space‐agency workers.