The production of heavy mesons and hyperons by π−-mesons of 4.5 GeV/c

A systematic investigation has been carried out, using nuclear photographic emulsions, into the production of heavy unstable particles by π−-mesons of 4.5 GeV/c. From 2854 stars, 4 hyperons and 4 heavy mesons were found which had velocities of less than 0.7c, and which satisfied certain geometrical selection criteria. One hyperon produces a secondary π-meson which comes to rest in the emulsion stack. The mass of this hyperon, shown to be negatively charged by the nuclear capture of its secondary particle, is (2352±5) mo.