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Baryons and mesons Quarks and gluons carry color. However, the force felt between colored objects increases with the distance between the objects, like the force of a spring. Due to this property, nature only allows net-colorless objects on scales larger than 1.0 E-15 m. Colorless objects can be produced from colored quarks in two different ways. A meson is a combination of a quark and anti-quark of the opposite color. Examples of mesons are the p, h, r and w mesons. Mesons do not last long because they have no net baryon or net lepton number and can decay. For instance a p0 meson can decay into two photons. An object made of a red, a green and a blue quark is also colorless. These are called baryons. Examples of baryons are protons and neutrons, although there are many others. One example of a baryon is the L baryon which is comprised of one up, one down and one strange quark. Leptons and photons can exist by themselves, rather than in groups, because they have no color. |
