Color confinement

<p>In <a href="/facts/Quantum_chromodynamics/3cA2ctyb">quantum chromodynamics</a> (QCD), color confinement, often simply called confinement, is the phenomenon that <a href="/facts/Color_charge/aWS1xsCR">color-charged</a> particles (such as <a href="/facts/Quark/hwuuVkV5">quarks</a> and <a href="/facts/Gluon/t6YH8I21">gluons</a>) cannot be isolated, and therefore cannot be directly observed in normal conditions below the <a href="/facts/Hagedorn_temperature/hSd64N3n">Hagedorn temperature</a> of approximately 2 <a href="/facts/Tera-/qWTDFAI1">tera</a><a href="/facts/Kelvin/E3trzC4C">kelvin</a> (corresponding to energies of approximately 130–140 M<a href="/facts/Electron_volt/YMT1fqX9">eV</a> per particle).  Quarks and gluons must clump together to form <a href="/facts/Hadron/C0sd1zty">hadrons</a>. The two main types of hadron are the <a href="/facts/Meson/9R0kIc1q">mesons</a> (one quark, one antiquark) and the <a href="/facts/Baryon/QFwAUWK2">baryons</a> (three quarks).  In addition, colorless <a href="/facts/Glueball/4oT4EPUY">glueballs</a> 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.
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Color confinement open-in-new

Color confinement