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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
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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- Fall '13