sigma particle

noun Physics.

an unstable hyperon having positive, negative, or zero electric charge and strangeness −1. Symbol: Σ

Origin of sigma particle

First recorded in 1960–65

Also called sigma baryon.

sigma baryon in Science

Any of three unstable subatomic particles in the baryon family, having a mass 2,328 to 2,343 times that of the electron and a positive, neutral, or negative electron charge. See Table at subatomic particle.