W-boson

The middle term is a Proca Lagrangian for a massive photon. Here the mass of this photon is assumed to be larger than the masses of the W and W° bosons. The current / 31( is determined by the charged fermions with masses given by the Yukawa interactions with the Higgs held. These are yet to be explored. Now consider the term in the Euler-Lagrange equation... 

The well-known proton, neutron, and electron are now thought to be members of a group that includes other fundamental particles that have been discovered or hypothesized by physicists. These very elemental particles, of which all matter is made, are now thought to belong to one of two families namely, quarks or leptons. Each of these two families consists of six particles. Also, there are four different force carriers that lead to interactions between particles. The six members or flavors of the quark family are called up, charm, top, down, strange, and bottom. The force carriers for the quarks are the gluon and the photon. The six members of the lepton family are the e neutrino, the mu neutrino, the tau neutrino, the electron, the muon particle, and the tau particle. The force carriers for these are the w boson and the z boson. Furthermore, it appears that each of these particles has an anti-particle that has an opposite electrical charge from the above particles. 

W boson (W particle) Either of a pair of elementary particles (W or W ), classified as intermediate vector bosons, that are believed to transmit the weak interaction (see FUNDAMENTAL INTERACTIONS) in much the same way as photons transmit the electromagnetic interaction. They are not, however, massless like photons, and are believed to... 

Z boson An electrically neutral elementary particle, Z°, which-like W bosons-is thought to mediate the weak interactions in the electroweak theory. The Z° boson was discovered at CERN in 1983 and has a mass of about 90 GeV as had been predicted from theory. 

W boson. This is interpreted as a signature that the weak interaction mixes the quark states. It is sufficient to assume that either the upper or the lower quark states are mixed. The lower quark states are taken to be mixed, and that is indicated by the apostrophes in O Table 10.1 on the symbols of the lower quarks. There is experimental evidence, neutrino oscillations, for the neutrinos also having a tiny little mass (Fukuda and et al. 1998) then of course the lepton states will be mixed as well for the weak interaction (Maid et al. 1962). 

The W boson originating If om the weak decay of the b quark decays either hadron-ically or leptonicaUy. Within this analysis the semileptonic decay of b quarks into muons is studied since the muon provides a clean signature which is relatively easy... 

When these ideas were first developed, there was no hint, experimentally, of the actual existence of W bosons. The situation has changed dramatically in the last few years and Ws and their neutral counterparts Z°s are produced copiously at CERN, in Geneva, and at Fermilab, near Chicago, in e e , pp and pp collisions. 

Fig. 5.4. Calculated parton model cross-sections for the production of W bosons in pp and pp collisions. Solid and dashed lines correspond to different assumed parton distribution functions. (Prom Quigg, 1977.)...

Another decay mode, especially relevant at LEP energies for light Higgs, is > 27 which goes via one-loop diagrams involving W bosons, quarks and leptons ... 

In accord with the assumption of exact universality between leptons and bare quarks, the interaction of the bare quarks with the W boson will be given by terms analogous to (4.2.26), which are, of course, diagonal in flavour. But these terms, when re-expressed in terms of the fields in (9.7.15) become non-diagonal in flavour. 

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