A gluon is a spin-one quantum of the quantum chromodynamics gauge field. There are eight color-adjoint gluon components, and the gauge description has zero gluon mass. Unlike the neutral photon of an Abelian theory, gluons themselves carry the charge associated with their interaction, producing three- and four-gluon vertices.
A gluon is not observed as an isolated color-charged final particle because of confinement. An energetic gluon can instead initiate a jet after radiation and hadronization. Gluons also contribute to a proton's momentum distribution and energy even though its net valence flavor content is described as . Color labels are internal gauge labels, not ordinary visible colors or eight independently identifiable classical substances.
A QCD branching in which a gluon produces a quark-antiquark pair or two gluons. Quark-pair production supplies a perturbative source of sea quarks. Its rates depend on scale and on the allowed daughter quark masses.
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Force carrier of quantum chromodynamics, like the photon is the force carrier of quantum electrodynamics.
One big difference is that it carrier itself color charge.