antiparticle(redirected from Stückelberg-Feynman interpretation)
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either of a pair of elementary particles that have electric charges and magnetic moments of opposite sign and are the same in all other properties, such as mass, lifetime, and spin, e.g., the electron and positron. Every particle has an antiparticle. When antiparticles collide, they are annihilated, and their mass is converted to energy in the form of gamma rays.