3 research outputs found
Electroweak Limits on General New Vector Bosons
We study extensions of the Standard Model with general new vector bosons. The
full Standard Model gauge symmetry is used to classify the extra vectors and
constrain their couplings. We derive the corresponding effective Lagrangian,
valid at energies lower than the mass of the extra vectors, and use it to
extract limits from electroweak precision observables, including LEP 2 data. We
consider both universal and nonuniversal couplings to fermions. We study the
interplay of several extra vectors, which can have the effect of opening new
regions in parameter space. In particular, it allows to explain the anomaly in
the bottom forward-backward asymmetry with perturbative couplings. Finally, we
analyze quantitatively the implications for the Higgs mass.Comment: Latex 50 pages, 12 eps figures. Typos fixed, comments and references
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Electroweak constraints on see-saw messengers and their implications for LHC
We review the present electroweak precision data constraints on the mediators
of the three types of see-saw mechanisms. Except in the see-saw mechanism of
type I, with the heavy neutrino singlets being mainly produced through their
mixing with the Standard Model leptons, LHC will be able to discover or put
limits on new scalar (see-saw of type II) and lepton (see-saw of type III)
triplets near the TeV. If discovered, it may be possible in the simplest models
to measure the light neutrino mass and mixing properties that neutrino
oscillation experiments are insensitive to.Comment: 8 pages, 4 figures, To appear in the Proceedings of the Rencontres de
Moriond 2008 EW Session, La Thuile (Italy), March 1-8, 200
The Impact of Kaluza-Klein Excited W Boson on the Single Top at LHC and Comparison with other Models
We study the s-channel single top quark production at the LHC in the context
of extra dimension theories, including the Kaluza-Klein (KK) decomposition. It
is shown that the presence of the first KK excitation of gauge boson can
reduce the total cross section of s-channel single top production considerably
if () for () in
proton-proton collisions. Then the results will be compared with the impacts of
other beyond Standard Model (SM) theories on the cross section of single top
s-channel. The possibility of distinguishing different models via their effects
on the production cross section of the s-channel is discussed.Comment: 23 pages,6 figure