Gauge boson
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Gauge bosons are bosonic particles which act as carriers of the fundamental forces of Nature. More specifically, elementary particles whose interactions are described by gauge theory exert forces on each other by the exchange of gauge bosons, usually as virtual particles.
In the Standard Model, there are three kinds of gauge bosons: photons, vector bosons, and gluons. Each corresponds to three main forces: electromagnetic force, weak force, and strong force. Photons are gauge bosons of the electromagnetic interaction (electromagnetic force), weak bosons or "vector bosons" are the bosons of weak interaction (weak force), and gluons are the bosons of strong interaction (strong force). Because of confinement, isolated gluons do not occur, at least at low energies. What result instead are massive glueballs.
In a quantized gauge theory, gauge bosons are quanta of the gauge fields. Consequently, there are as many gauge bosons as there are generators of the gauge field. For example, the 8 generators of SU(3) correspond to 8 different varieties of gluons in quantum chromodynamics. For technical reasons such as gauge invariance, Gauge bosons are described mathematically by field equations for massless particles. At a naive theoretical level therefore, all gauge bosons are required to be massless, and the forces that they describe are required to be long-ranged. The conflict between this idea and experimental evidence regarding the short range of weak interactions requires further theoretical insight, and is understood today in terms of the Higgs mechanism. This process also results in massive gauge bosons from hitherto massless particles. Photons and gluons are massless gauge bosons, whereas the W and Z bosons of electroweak theory have mass.
There is a fourth kind of gauge boson, the graviton, which has been postulated as the carrier of the gravitational force, but in the absence of experimental evidence and a mathematically coherent theory of quantum gravity, this is a speculative matter at the moment.
Basic concept
Gauge bosons are used as a way of explaining how all forces of nature vary inversely with the square of the distance between the two objects. If particles are imagined as passing quanta of forces between the two objects, then this would be the expected behaviour.
See also
| edit | |
| Fermions: Quarks | Leptons | |
| Quarks: Up | Down | Strange | Charm | Bottom | Top | |
| Leptons: Electron | Muon | Tau | Neutrinos | |
| Gauge bosons: Photon | W and Z bosons | Gluons | |
| Not yet observed: Higgs boson | Graviton | Other hypothetical particles | |
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