A type of spin ½ baryon. There are three types of sigma particles, denoted Σ‎⁻, Σ‎⁰, Σ‎⁺, for the negatively charged, electrically neutral, and positively charged forms, respectively. The quark content of the sigma particles are Σ‎⁻ (dds), Σ‎⁰ (dus), Σ‎⁺ (uus), where d, u, and s denote down, up, and strange, respectively. The masses of the sigma particles are 1189.36 MeV (Σ‎⁺), 1192.46 MeV (Σ‎⁰), 1197.34 MeV (Σ‎⁻); their average lifetimes are 0.8×10⁻¹⁰ s (Σ‎⁺), 5.8×10⁻²⁰ s (Σ‎⁰), and 1.5×10⁻¹⁰ s (Σ‎⁻).