HYPERON

a subatomic particle that is a quasi-stable member of the class of particles known as baryons and that is more massive than the nucleons (protons and neutrons). Hyperons, in order of increasing mass, include one lambda-zero, a triplet of sigmas, a doublet of xi particles, and the omega singlet. Each of the seven has an antiparticle. The different hyperons were detected during the period 194764; the discovery of the omega-minus hyperon was suggested by the Eightfold Way (q.v.) of classifying strongly interacting particles (hadrons). Hyperons are produced by the strong nuclear force in the time it takes for a particle traveling at nearly the speed of light to cross the diameter of a subatomic particle, but their decay by the weak nuclear force (which is involved in radioactive decay) takes millions of millions of times longer. Because of this behaviour, they, along with K mesons (kaons), with which they are often produced, were named strange particles.