Color charge

In particle physics, the color charge is a term for those physical property of the elementary quarks and gluons, which is characteristic of the strong interactions. There are three different charges that add up to zero charge for this strong force ( color force). In analogy to the additive color mixing, they are called red, green and blue, the color charges of the corresponding antiparticles antired, anti- green and anti- blue.

Note that the colors of the color charge have nothing to do with the optical color of objects; the term " color" and the use of color names for the charges are instead to be understood as mere analogies to express the combination of three qualitatively different values ​​to a neutral. The concept was proposed in 1964 by Oscar Wallace Greenberg, Moo -Young Han ( born 1934 ) and Yoichiro Nambu (* 1921).

Confinement and white particles

The phenomenon of confinement (English imprisonment, confinement ) states that particles with color charge can never occur individually, but must be bound in a total white ( color neutral ) particles always.

A white particles can be formed:

  • By combining the three colors,
  • By a combination of three anti- colors or
  • By combining a color with its anti- color.

All three possibilities actually occur.

Reason for the confinement is that - unlike the electromagnetic field - not just the quarks as the strong force reacting elementary particles, but also the gluons carry a color charge as generating field quanta of the strong interaction and attract each other, while the field quantum of the electromagnetic interaction which photons are uncharged. This is the energy that would be needed to separate particles with color charge each other so large that it would be sufficient for the production of particle-antiparticle pairs. This would be a total complement the items back to color-neutral objects. For this reason, individual quarks or gluons will never be able to observe directly.

The confinement is also the reason why the strong force is short range, although the gluons as the photons are massless.