Compound Hypothesis for the Heavy Unstable Particles. II

The compound hypothesis for hyperons and heavy mesons is restated, modifying an earlier assumption on the isotopic spin of θ⁰. θ mesons and θ mesons (antiparticles) are assumed to have isotopic spin T=1/2, as proposed by Gell-Mann. The total number of heavy mesons (θ mesons minus θ mesons) is conserved in strong interactions (fast reactions). The fundamental reaction is thus pair creation of θ+θ, with θ mesons free and θ mesons either free or bound to nucleons (N). Hence N+θ can form $T=0$ and $T=1$ multiplets which are identified with the Λ⁰ singlet and the Σ triplet, respectively. The facts known about hyperons, associated production, and interaction of heavy mesons with nucleons are consistent with our assumptions. A discussion of T-multiplets among hypernuclei is given. Some experiments which may throw new light on the compound hypothesis are discussed.