Preon research is motivated by the desire to: 2.2 Unresolved problems with the Standard Model.2.1 Comparisons of quarks, leptons, and bosons.

Based on these rules, the preon models try to explain the Standard Model, often predicting small discrepancies with this model and generating new particles and certain phenomena, which do not belong to the Standard Model. Each of the preon models postulates a set of fewer fundamental particles than those of the Standard Model, together with the rules governing how those fundamental particles combine and interact. More recent preon models also account for spin-1 bosons, and are still called 'preons'. When the term 'preon' was coined, it was primarily to explain the two families of spin- 1 / 2 fermions: quarks and leptons. For example, the proton spin puzzle, the EMC effect, the distributions of electric charges inside the nucleons, as found by Hofstadter in 1956, and the ad hoc CKM matrix elements. In the hadronic sector, some effects are considered anomalies within the Standard Model. W bosons have six preons and quarks have only three. Preons come in four varieties, plus, anti-plus, zero and anti-zero. Interest in preon models peaked in the 1980s but has slowed, as the Standard Model of particle physics continues to describe physics mostly successfully, and no direct experimental evidence for lepton and quark compositeness has been found. The word was coined by Jogesh Pati and Abdus Salam, in 1974. In particle physics, preons are point particles, conceived of as sub-components of quarks and leptons. For the chemical pollutants, see Chlorofluorocarbon.

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