QCD is a type of quantum field theory called a non-abelian gauge theory with symmetry group SU. The QCD analog of electric charge is a property called color, gluons are the force carrier of the theory, like photons are for the electromagnetic force in quantum electrodynamics. The theory is an important part of the Standard Model of particle physics, a large body of experimental evidence for QCD has been gathered over the years. QCD enjoys two peculiar properties, Confinement, which means that the force between quarks does not diminish as they are separated. Although analytically unproven, confinement is widely believed to be true because it explains the consistent failure of free quark searches, asymptotic freedom, which means that in very high-energy reactions, quarks and gluons interact very weakly creating a quark–gluon plasma. This prediction of QCD was first discovered in the early 1970s by David Politzer, Frank Wilczek, for this work they were awarded the 2004 Nobel Prize in Physics. The phase transition temperature between two properties has been measured by the ALICE experiment to be well above 160 MeV. Below this temperature, confinement is dominant, while above it, american physicist Murray Gell-Mann coined the word quark in its present sense. It originally comes from the phrase Three quarks for Muster Mark in Finnegans Wake by James Joyce, Gell-Mann, however, wanted to pronounce the word to rhyme with fork rather than with park, as Joyce seemed to indicate by rhyming words in the vicinity such as Mark. Gell-Mann got around that by supposing that one ingredient of the line Three quarks for Muster Mark was a cry of Three quarts for Mister, earwickers pub, a plausible suggestion given the complex punning in Joyces novel. The three kinds of charge in QCD are usually referred to as color charge by loose analogy to the three kinds of color perceived by humans, other than this nomenclature, the quantum parameter color is completely unrelated to the everyday, familiar phenomenon of color. Since the theory of charge is dubbed electrodynamics, the Greek word χρῶμα chroma color is applied to the theory of color charge. With the invention of bubble chambers and spark chambers in the 1950s, experimental particle physics discovered a large and it seemed that such a large number of particles could not all be fundamental. First, the particles were classified by charge and isospin by Eugene Wigner and Werner Heisenberg, then, in 1953, according to strangeness by Murray Gell-Mann and Kazuhiko Nishijima. To gain greater insight, the hadrons were sorted into groups having similar properties and masses using the way, invented in 1961 by Gell-Mann. The problem considered in this preprint was suggested by Nikolay Bogolyubov, in the beginning of 1965, Nikolay Bogolyubov, Boris Struminsky and Albert Tavkhelidze wrote a preprint with a more detailed discussion of the additional quark quantum degree of freedom. This work was presented by Albert Tavchelidze without obtaining consent of his collaborators for doing so at an international conference in Trieste. A similar mysterious situation was with the Δ++ baryon, in the quark model, han and Nambu noted that quarks might interact via an octet of vector gauge bosons, the gluons
Image: Fluxtube meson
The pattern of strong charges for the three colors of quark, three antiquarks, and eight gluons (with two of zero charge overlapping).