Hip Glossary: Quark

In particle physics, quarks are one of the two basic constituents of matter (the other Standard Model fermions are the leptons).

Antiparticles of quarks are called antiquarks. Quarks are the only fundamental particles that interact through all four of the fundamental forces. The derivation of this word comes from the book Finnegans Wake by James Joyce, where seabirds give "three quarks", akin to three cheers, and probably just take on the sound a seabird makes, like "quack" is for ducks.

Akin to the name itself, the properties of quarks (Up, Down, Top, Bottom, Strange, and Charm) are generally non-sequiturs, chosen largely to illustrate the arbitrary nature of the need to name them something which can be easily remembered and used.

An important property of quarks is called confinement, which states that individual quarks are not seen because they are always confined inside subatomic particles called hadrons (e.g., protons and neutrons); an exception is the top quark, which decays so quickly that it does not hadronize, and can therefore be observed more directly via its decay products. Confinement began as an experimental observation, and is expected to follow from the modern theory of strong interactions, called quantum chromodynamics (QCD). Although there is no mathematical derivation of confinement in QCD, it is easy to show using lattice gauge theory.