![]() Analysis of data collected from such sources as the Super-Kamiokande neutrino detector has yielded no evidence of X and Y bosons. Such bosons would be even more massive than W and Z bosons due to symmetry breaking. ![]() The hypothetical X and Y bosons mediate interactions between quarks and leptons, hence violating conservation of baryon number and causing proton decay. ![]() The Georgi–Glashow model predicts additional gauge bosons named X and Y bosons. Beyond the Standard Model Grand unification theories This theory also predicts the existence of a scalar Higgs boson, which has been observed in experiments at the LHC. This VEV couples to three of the electroweak gauge bosons (W +, W − and Z), giving them mass the remaining gauge boson remains massless (the photon). As a result, the universe is permeated by a nonzero Higgs vacuum expectation value (VEV). This field undergoes spontaneous symmetry breaking due to the shape of its interaction potential. ![]() In the Higgs mechanism, the four gauge bosons (of SU(2)×U(1) symmetry) of the unified electroweak interaction couple to a Higgs field. The conflict between this idea and experimental evidence that the weak and strong interactions have a very short range requires further theoretical insight.Īccording to the Standard Model, the W and Z bosons gain mass via the Higgs mechanism. Therefore, at a naïve theoretical level, all gauge bosons are required to be massless, and the forces that they describe are required to be long-ranged. Otherwise, the mass terms add non-zero additional terms to the lagrangian under gauge transformations, violating gauge symmetry. Gauge invariance requires that gauge bosons are described mathematically by field equations for massless particles. The three W and Z bosons correspond (roughly) to the three generators of SU(2) in electroweak theory. In quantum chromodynamics, the more complicated group SU(3) has eight generators, corresponding to the eight gluons. In quantum electrodynamics, the gauge group is U(1) in this simple case, there is only one gauge boson, the photon. Consequently, there are as many gauge bosons as there are generators of the gauge field. In a quantized gauge theory, gauge bosons are quanta of the gauge fields. Isolated gluons do not occur because they are colour-charged and subject to colour confinement. The Standard Model of particle physics recognizes four kinds of gauge bosons: photons, which carry the electromagnetic interaction W and Z bosons, which carry the weak interaction and gluons, which carry the strong interaction. Gauge bosons are different from the other kinds of bosons: first, fundamental scalar bosons (the Higgs boson) second, mesons, which are composite bosons, made of quarks third, larger composite, non-force-carrying bosons, such as certain atoms. Therefore, all known gauge bosons are vector bosons. All known gauge bosons have a spin of 1 for comparison, the Higgs boson has spin zero and the hypothetical graviton has a spin of 2. Photons, W and Z bosons, and gluons are gauge bosons. Elementary particles, whose interactions are described by a gauge theory, interact with each other by the exchange of gauge bosons, usually as virtual particles. In particle physics, a gauge boson is a bosonic elementary particle that acts as the force carrier for elementary fermions. The Standard Model of elementary particles, with the gauge bosons in the fourth column in red
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