hyperon

A hyperon is a baryon that contains one or more strange quarks (s) and no charm, bottom, or top quarks. Hyperons carry nonzero strangeness and are heavier than nucleons. They participate in strong interactions but decay via the weak interaction, giving them lifetimes on the order of 10^-10 seconds.

The lightest hyperons are the Lambda, Sigma, Xi, and Omega baryons. Their common members and quark contents are: Lambda zero (Λ^0) with quark content uds; Sigma plus (Σ^+) with uus, Sigma zero (Σ^0) with uds, Sigma minus (Σ^−) with dds; Xi zero (Ξ^0) with uss and Xi minus (Ξ^−) with dss; and Omega minus (Ω^−) with sss. In the quark model, hyperons form part of the baryon multiplets, with the Lambda and Sigma in the baryon octet, Xi in the same family, and Omega in the decuplet as a spin-3/2 state.

Hyperons are produced in high-energy hadronic and leptonic collisions and in decays of heavier particles. They have masses roughly between 1.1 and 1.7 GeV/c^2, and their spins are 1/2 for Λ, Σ, and Ξ, with Ω^− having spin 3/2. Magnetic moments and other properties have been measured, contributing to the development of the quark model and SU(3) flavor symmetry.

In astrophysics, hyperons may appear in dense stellar matter, such as neutron stars, where hyperon-nucleon and hyperon-hyperon interactions influence the equation of state and stellar properties. Hyperons remain a key tool for studying strong and weak interaction dynamics and the role of strangeness in hadronic matter.