elementary particle

The particle-physics term elementary particle refers to particles that have no well-accepted internal structure; basically what is well-accepted about them is their quantum numbers. The standard model of particle physics lists and categorizes elementary particles, demonstrating their interrelationships. They are subdivided into elementary fermions and elementary bosons, the former including quarks and leptons, and the latter, photons, W and Z bosons, gluons, and Higgs bosons. Leptons include electrons, muons, and tau particles, and neutrinos.