127 research outputs found
Top-BESS model and its phenomenology
We introduce the top-BESS model which is the effective description of the
strong electroweak symmetry breaking with a single new SU(2)_L+R triplet vector
resonance. The model is a modification of the BESS model in the fermion sector.
The triplet couples to the third generation of quarks only. This approach
reflects a possible extraordinary role of the top quark in the mechanism of
electroweak symmetry breaking. The low-energy limits on the model parameters
found provide hope for finding sizable signals in the LHC Drell-Yan processes
as well as in the s-channel production processes at the ILC. However, there are
regions of the model parameter space where the interplay of the direct and
indirect fermion couplings can hide the resonance peak in a scattering process
even though the resonance exists and couples directly to top and bottom quarks.Comment: published in Physical Review D, minor changes in text, 21 pages, 37
figure
The vector resonance triplet with the direct coupling to the third quark generation
The effective Lagrangian with scalar and vector resonances that might result
from new strong physics beyond the SM is formulated and studied. In particular,
the scalar resonance representing the recently discovered 125-GeV boson is
complemented with the SU(2)_{L+R} triplet of hypothetical vector resonances.
Motivated by experimental and theoretical considerations, the vector resonance
is allowed to couple directly to the third quark generation only. The coupling
is chiral-dependent and the interaction of the right top quark can differ from
that of the right bottom quark. To estimate the applicability range of the
effective Lagrangian the unitarity of the gauge boson scattering amplitudes is
analyzed. The experimental fits and limits on the free parameters of the vector
resonance triplet are investigated.Comment: 17 pages, 10 figures, to be published in The European Physical
Journal C. arXiv admin note: text overlap with arXiv:1301.212
W-Pair Production in the Process and Measurement of the and Couplings
We performed a detailed analysis of the process where we included all tree level Feynman diagrams that contribute to
this final state. We studied the sensitivity of this process to anomalous
trilinear gauge boson couplings of the and vertices using two
popular parametrizations. We used a maximum likelihood analysis of a five
dimensional differential cross-section based on the and decay product
angular distributions. We concentrated on LEP-200 energies, taking
GeV, and energies appropriate to the proposed Next Linear
Collider (NLC), a high energy collider with center of mass energies
and 1~TeV. At 175 GeV, can be measured to about , to and to , to
and to . at 95\% C.L. assuming
500~pb integrated luminosity. Although these will be improvements of
existing measurements they are not sufficiently precise to test the standard
model at the loop level and are unlikely to see deviations from SM
expectations. At 500~GeV with 50~fb integrated luminosity, can
be measured to about , and to
and and to at 95\% C.L. while at 1 TeV
with 200~fb integrated luminosity, and can be
measured to about and respectively. The 500~GeV
measurements will be at the level of loop contributions to the couplings and
may show hints of new physics while the 1~TeV should be sensitive to new
physics at the loop level.Comment: Latex file uses revtex version 2 4 figures (uuencoded) will be added
with figures command. Full postcript version with embedded figures is
available at ftp://ftp.physics.carleton.ca/pub/theory/godfrey/ocipc9503.p
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