Charted territories of particle physics

This chart recalls the features of the classification of particles and their roles concerning the basic interactions. The lepton group contains 3 particles: the muon, the tau and the electron, each one being associated with a type of neutrinos. The quarks existent in 6 different flavours, they are submitted to the strong interaction and they cannot be observed in isolation. Hadrons are composite particles, they contain other particles, quarks and gluons. Bosons are particles that are the bearers of the fundamental interactions: the photon for the electromagnetic interaction, the gluon for the strong interaction and intermediate bosons for the weak interaction. The Higgs boson forms the basis of a mechanism that gives mass to other particles including itself but excepting photons, gluons and neutrinos that remain massless in the framework of the standard model. (A.C.)