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W and Z bosons decay to fermion pairs but neither the W nor the Z bosons have sufficient energy to decay into the highest-mass top quark. Neglecting phase space effects and higher order corrections, simple estimates of their branching fractions can be calculated from the coupling constants.
Because exchange of W bosons involves a transfer of electric charge (as well as a transfer of weak isospin, while weak hypercharge is not transferred), it is known as "charged current". By contrast, exchanges of Z bosons involve no transfer of electrical charge, so it is referred to as a "neutral current". In the latter case, the word "current ...
These three composite bosons are the W +, W −, and Z 0 bosons actually observed in the weak interaction. The fourth electroweak gauge boson is the photon (γ) of electromagnetism, which does not couple to any of the Higgs fields and so remains massless. [23] This theory has made a number of predictions, including a prediction of the masses of ...
In the Standard Model, vector (spin-1) bosons (gluons, photons, and the W and Z bosons) mediate forces, whereas the Higgs boson (spin-0) is responsible for the intrinsic mass of particles. Bosons differ from fermions in the fact that multiple bosons can occupy the same quantum state (Pauli exclusion principle).
Higgs boson production: Via gluons and top quarks: Via quarks and W or Z bosons: Quad cancellations: One of the many cancellations to the quadratic divergence to squared mass of the Higgs boson which occurs in the MSSM. Primakoff effect: production of neutral pseudoscalar mesons by photons interacting with an atomic nucleus: Delbrück scattering
Because the W′ comes from the breaking of an SU(2), it is generically accompanied by a Z′ boson of (almost) the same mass and with couplings related to the W′ couplings. Another model with W′ bosons but without an additional SU(2) factor is the so-called 331 model with β = ± 1 3 . {\displaystyle \;\beta =\pm {\tfrac {1}{\sqrt {3\;}}}~.}
Elementary bosons responsible for the four fundamental forces of nature are called force particles (gauge bosons). The strong interaction is mediated by the gluon, the weak interaction is mediated by the W and Z bosons, electromagnetism by the photon, and gravity by the graviton, which is still hypothetical.
Additionally, we know experimentally that the W and Z bosons are massive, but a boson mass term contains the combination e.g. A μ A μ, which clearly depends on the choice of gauge. Therefore, none of the standard model fermions or bosons can "begin" with mass, but must acquire it by some other mechanism.