RevModPhys.84.1477】Tests of the standard electroweak model at the energy frontier

Higgs boson of unknown mass but with denite couplings

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Unformatted text preview: but with definite couplings to other particles. The discovery of this Higgs particle is one of the driving ambitions of particle physicists, and was a primary motivation for the LHC. As mentioned in Sec. II.A, this simple model is consistent with precision electroweak data with a Higgs particle close to the present experimental lower bound of mH > 114 GeV=c2 . This consistency does not rule out more exotic possibilities, however, such as two (or more) Higgs doublets, Higgs singlets and triplets, composite Higgs bosons, and other alternative models of electroweak symmetry breaking. III. ELECTROWEAK GAUGE BOSONS In the SM, the W and Z bosons mediate the weak force and acquire mass through the Higgs mechanism, as described in " Sec. II. The W boson was discovered in 1983 in pp collisions at the CERN Super Proton Synchrotron by the UA1 and UA2 experiments (Arnison et al., 1983a; Banner et al., 1983), with discovery of the Z boson soon to follow (Arnison et al., 1983b; Bagnaia et al., 1983). The discovery of these gauge bosons at CERN represents a dramatic validation of GlashowSalam-Weinberg theory which predicted the existence of neutral currents mediated by a new gauge boson, the Z boson, and predicted the W bosons to describe nuclear decay and, together with the massless photon, these comprise the gauge bosons of the electroweak interaction. High precision studies of the Z boson properties made by the LEP collaborations and the SLD Collaboration (Abbiendi et al., 2006b) using eþ eÀ collisions provided stringent tests of electroweak theory. " The W and Z bosons are copiously produced in pp collisions at the Fermilabffi Tevatron due to their large production pffiffi cross sections at s ¼ 1:96 TeV and the high integrated luminosity data sets available from the CDF and D0 experiments during Run II. Detailed measurement of the W and Z properties at the Tevatron is not only important to further test Glashow-Salam-Weinberg theory and the electroweak symmetry breaking mechanism in the SM but also to search for new physics beyond the SM using the highest energy collisions currently available. We summarize the current Tevatron measurements of W and Z properties in Sec. III.A–III.D. The production of heavy vector boson pairs (WW , WZ, and ZZ) is far less common than inclusive W and Z production. 1480 Hobbs, Neubauer, and Willenbrock: Tests of the standard electroweak model at . . . " While a W boson is produced in every 3 million pp collisions and a Z boson in every 10 million, the production of a WW pair is a once in 6 billion event, WZ a once in 20 billion event, and ZZ a once in 60 billion event. Diboson production is sensitive to the triple gauge couplings (TGCs) between the bosons themselves via an intermediate virtual boson. The boson TGCs are an important consequence of the nonAbelian nature of the SM electroweak gauge symmetry group. At the highest accessible energies available at the Fermilab Tevatron, diboson production provid...
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