Elementary particles. Computer illustration showing the particles included in the Standard Model of particle physics, which describes the Universe in terms of matter (fermions) and force (bosons). It comprises 17 elementary particles: 6 quarks, 6 leptons, 4 force-carrying particles (gauge bosons) and the Higgs Boson. Scientists think that another gauge boson, the Graviton hypothetical particle, is responsible for generating gravity, but for now this is not included within the Standard Model (here, all the hypothetical particles are indicated by question marks). This diagram also shows the conjectured supersymmetric particles. Supersymmetry is an extension of the Standard Model that predicts a superpartner for each elementary particle; thus, each boson