2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/104022This paper proves that a particle with mass different of zero cannot be its own antiparticle. Hence, particles such as pi-zero,eta-zero, and Z-zero must have their correspondent antiparticles.16 pages, v2 enlarged, v3 additionGeneral Physicstext