Editing Color confinement (section)

{{Short description|Phenomenon in quantum chromodynamics}}
[[Image:Quark confinement.svg|right|thumb|350px|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.]]
[[File:Gluon tube-color confinement animation.gif|thumb|300px|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 charge|color-charged]] particles (such as [[quark]]s and [[gluon]]s) cannot be isolated, and therefore cannot be directly observed in normal conditions below the [[Hagedorn temperature]] of approximately 2 [[tera-|tera]][[kelvin]] (corresponding to energies of approximately 130–140 M[[electron volt|eV]] per particle).<ref>{{cite book
 |last1=Barger |first1=V.
 |last2=Phillips |first2=R. 
 |year=1997
 |title=Collider Physics
 |publisher=[[Addison–Wesley]]
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}}</ref><ref>{{Cite book<!--Deny Citation Bot-->
 |last=Greensite |first=J.
 |year=2011
 |title=An introduction to the confinement problem
 |series=Lecture Notes in Physics
 |volume=821
 |publisher=[[Springer Science+Business Media|Springer]]
 |isbn=978-3-642-14381-6
 |bibcode=2011LNP...821.....G
 |doi=10.1007/978-3-642-14382-3
}}</ref>  Quarks and gluons must clump together to form [[hadron]]s. The two main types of hadron are the [[meson]]s (one quark, one antiquark) and the [[baryon]]s (three quarks).  In addition, colorless [[glueball]]s 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.<ref>
{{cite book
 |last1=Wu |first1=T.-Y. 
 |author2-link=Woei-Yann Pauchy Hwang |last2=Hwang |first2=Pauchy W.-Y. 
 |year=1991
 |title=Relativistic quantum mechanics and quantum fields
 |pages=321
 |publisher=[[World Scientific]]
 |isbn=978-981-02-0608-6
}}</ref>