Antiquark

An antiquark is the antiparticle of a quark, with opposite electric charge and corresponding opposite internal quantum numbers. Antiquarks combine with quarks to form mesons and with other antiquarks to form antimatter counterparts of baryons.

Quark: A fundamental fermion that carries color charge and participates in the strong interaction. An antiquark is its antiparticle, with opposite electric and color charges.
Quantum chromodynamics: The quantum field theory describing strong interactions among quarks and gluons. It governs antiquark color interactions and their binding inside hadrons.
Meson: A hadron composed of a quark and an antiquark bound by the strong interaction. Mesons are the simplest common bound systems containing an antiquark.
Pion: A light meson occurring as a positively charged, negatively charged, or neutral particle. Charged pions contain an up quark paired with a down antiquark, or the reverse.
Gottfried sum rule: A relation connecting a deep-inelastic scattering integral to the flavor distributions of quarks in the proton. Its violation provided evidence that proton up and down antiquark distributions differ.
Color charge: A quantum charge in quantum chromodynamics, carried by quarks and gluons in three types. Antiquarks carry anticolor, which combines with quark color in color-neutral hadrons.
Pair production: The creation of a particle and its antiparticle, typically from energy or a high-energy collision. High-energy processes can create quark–antiquark pairs together.
Antibaryon: A baryon made from three antiquarks, carrying the corresponding antimatter quantum numbers. Its constituent antiquarks show how baryon structure extends to antimatter.
Kaon: A meson containing one strange or antistrange quark and one light quark or antiquark. Kaon states provide concrete examples of strange antiquarks in hadrons.
NuSea experiment: A Fermilab experiment that measured dimuon production in proton–deuteron and proton–proton collisions. Its data established a sizable difference between the proton's down and up antiquark distributions.

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