What do the colors of the quarks mean

Color charge

Color charge, colour, Color, charge-like quantum number that can take on the three values ​​red (r), green (g) and blue (b) and is assigned to the quarks; these appear as a color triplet for each flavor (u, d, ...)



on. The strong interaction created by quantum chromodynamics (QCD) is described, couples to the color charges. In processes of strong interaction, the color of a quark can change, however Not change its flavor quantum number. The gauge bosons of the strong interaction, the gluons, also carry color themselves and therefore interact with one another. A special property of the QCD ensures that the hadrons composed of quarks are always color singulets, that is, they appear color-neutral (›white‹). The baryons, which consist of three quarks, always appear as a superposition of different color combinations, which together form a totally antisymmetric configuration. This knowledge solved the so-called Δ++- Riddle of the old quark model without color: How should the Δ. Built up from three u-quarks in the same spin state++-Particles with a symmetrical quark wave function obey the Pauli principle, which prohibits such states of identical fermions? With the three color charges postulated by M. Gell-Mann, such a state can be constructed which is antisymmetric with respect to the color indices:



The quark-antiquark pair of a meson also forms a superposition of all colors (each as a color-anticolor pair). There are also direct experimental indications of the existence of color charges: on the one hand, the calculation of the pion decay width results Γ

γγ) = 7.87 (Nc / 3)2 eV, what three color charges (Nc = 3) good with the experimental value Γ = 7.95 ± 0.05 eV. On the other hand, the measured ratio