Color confinement

The color force favors confinement because at a certain range it is more energetically favorable to create a quark–antiquark pair than to continue to elongate the color flux tube. This is analogous to the behavior of an elongated rubber-band.
An animation of color confinement. If energy is supplied to the quarks as shown, the gluon tube elongates until it reaches a point where it "snaps" and forms a quark–antiquark pair. Thus single quarks are never seen in isolation.

In quantum chromodynamics (QCD), color confinement, often simply called confinement, is the phenomenon that color-charged particles (such as quarks and gluons) cannot be isolated, and therefore cannot be directly observed in normal conditions below the Hagedorn temperature of approximately 2 terakelvin (corresponding to energies of approximately 130–140 MeV per particle).[1][2] Quarks and gluons must clump together to form hadrons. The two main types of hadron are the mesons (one quark, one antiquark) and the baryons (three quarks). In addition, colorless glueballs formed only of gluons are also consistent with confinement, though difficult to identify experimentally. Quarks and gluons cannot be separated from their parent hadron without producing new hadrons.[3]

  1. ^ Barger, V.; Phillips, R. (1997). Collider Physics. Addison–Wesley. ISBN 978-0-201-14945-6.
  2. ^ Greensite, J. (2011). An introduction to the confinement problem. Lecture Notes in Physics. Vol. 821. Springer. Bibcode:2011LNP...821.....G. doi:10.1007/978-3-642-14382-3. ISBN 978-3-642-14381-6.
  3. ^ Wu, T.-Y.; Hwang, Pauchy W.-Y. (1991). Relativistic quantum mechanics and quantum fields. World Scientific. p. 321. ISBN 978-981-02-0608-6.