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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 ...
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\;}}}~.}
where θ W is the weak mixing angle. The axes representing the particles have essentially just been rotated, in the (W 3, B) plane, by the angle θ W. This also introduces a mismatch between the mass of the Z 0 and the mass of the W ± particles (denoted as m Z and m W, respectively), = . The W 1 and W 2 bosons, in turn, combine to produce ...
W particles have electric charge – there are both positive and negative W particles – however the Z boson is also an exchange particle for the weak force but does not have any electrical charge. Exchange of a Z boson transfers momentum , spin , and energy , but leaves the interacting particles' quantum numbers unaffected – charge, flavor ...
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
The value of θ w varies as a function of the momentum transfer, ∆q, at which it is measured. This variation, or 'running', is a key prediction of the electroweak theory. The most precise measurements have been carried out in electron–positron collider experiments at a value of ∆q = 91.2 GeV/c, corresponding to the mass of the Z 0 boson, m Z.