2,799 research outputs found
Next-to-leading Order SUSY-QCD Calculation of Associated Production of Gauginos and Gluinos
Results are presented of a next-to-leading order calculation in perturbative
QCD of the production of charginos and neutralinos in association with gluinos
at hadron colliders. Predictions for cross sections are shown at the energies
of the Fermilab Tevatron and CERN Large Hadron Collider for a typical
supergravity (SUGRA) model of the sparticle mass spectrum and for a light
gluino model.Comment: 3 pages, latex, 4 figures, paper presented by E. L. Berger at ICHEP
2000, the XXXth International Conference on High Energy Physics July 27 -
August 2, 2000, Osaka, Japa
Indirect Searches for Dark Photon-Photon Tridents in Celestial Objects
We model and constrain the unique indirect detection signature produced by
dark matter particles that annihilate through a gauge symmetry into dark
photons that subsequently decay into three-photon final states. We focus on
scenarios where the dark photon is long-lived, and show that -ray
probes of celestial objects can set strong constraints on the dark
matter/baryon scattering cross section that in many cases surpass the power of
current direct detection constraints, and in some cases even peer into the
neutrino fog.Comment: 12 pages, 7 figures (8 sub-figures), 3 table
Electroweak Corrections to the Top Quark Decay
We have calculated the one-loop electroweak corrections to the decay t-> bW+,
including the counterterm for the CKM matrix elements V(tb). Previous
calculations used an incorrect delta V(tb) that led to a gauge dependent
amplitude. However, since the contribution stemming from delta V(tb) is small,
those calculations only underestimate the width by roughly one part in 10^5.Comment: 7 pages, 2 figure
Four Generations and Higgs Physics
In the light of the LHC, we revisit the implications of a fourth generation
of chiral matter. We identify a specific ensemble of particle masses and
mixings that are in agreement with all current experimental bounds as well as
minimize the contributions to electroweak precision observables. Higgs masses
between 115-315 (115-750) GeV are allowed by electroweak precision data at the
68% and 95% CL. Within this parameter space, there are dramatic effects on
Higgs phenomenology: production rates are enhanced, weak-boson-fusion channels
are suppressed, angular distributions are modified, and Higgs pairs can we
observed. We also identify exotic signals, such as Higgs decay to same-sign
dileptons. Finally, we estimate the upper bound on the cutoff scale from vacuum
stability and triviality.Comment: 11 pages, 7 figures, REVTe
Proton Lifetime and Baryon Number Violating Signatures at the LHC in Gauge Extended Models
There exist a number of models in the literature in which the weak
interactions are derived from a chiral gauge theory based on a larger group
than SU(2)_L x U(1)_Y. Such theories can be constructed so as to be
anomaly-free and consistent with precision electroweak measurements, and may be
interpreted as a deconstruction of an extra dimension. They also provide
interesting insights into the issues of flavor and dynamical electroweak
symmetry breaking, and can help to raise the mass of the Higgs boson in
supersymmetric theories. In this work we show that these theories can also give
rise to baryon and lepton number violating processes, such as nucleon decay and
spectacular multijet events at colliders, via the instanton transitions
associated with the extended gauge group. For a particular model based on
SU(2)_1 x SU(2)_2, we find that the violating scattering cross sections
are too small to be observed at the LHC, but that the lower limit on the
lifetime of the proton implies an upper bound on the gauge couplings.Comment: 36 page
Flavor changing scalar couplings and production at hadron colliders
We calculate the contributions of the flavor changing scalar ()
couplings arised from topcolor-assisted technicolor () models at
tree-level to the and production at the Tevatron and
experiments. We find that the production cross sections are very small at the
Tevatron with , which is smaller than 5 fb in most of the
parameter space of models. However, the virtual effects of the
couplings on the production can be easily detected at the
with via the final state
().Comment: 10 pages,5 figure
The t W- Mode of Single Top Production
The t W- mode of single top production is proposed as an important means to
study the weak interactions of the top quark. While the rate of this mode is
most likely too small to be observed at Run II of the Fermilab Tevatron, it is
expected to be considerably larger at the CERN LHC. In this article the
inclusive t W- rate is computed, including O(1 / log (m_t^2 / m_b^2))
corrections, and when combined with detailed Monte Carlo simulations including
the top and W decay products, indicate that the t W- single top process may be
extracted from the considerable t tbar and W+ W- j backgrounds at low
luminosity runs of the LHC.Comment: 16 pages, 4 figure
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