9,533 research outputs found
Neutralinos in E_6 inspired supersymmetric U(1)' models
The neutralino sector in E_6 inspired supersymmetric models with extra
neutral gauge bosons and singlet Higgs fields contains additional gaugino and
singlino states compared to the MSSM. We discuss the neutralino mixing in rank
5 and rank 6 models and analyze the supersymmetric parameter space where the
light neutralinos have mainly singlino or MSSM character. The neutralino
character, resonance effects of the new gauge bosons and, assuming mSUGRA-type
RGEs, different selectron masses lead to significant differences between the
MSSM and the extended models in neutralino production at an e^+e^- linear
collider. Beam polarization may improve the signatures to distinguish between
the models. In an appendix, we present the mass terms of the gauge bosons,
charginos and sfermions which show a significant different mass spectrum than
in the MSSM and give all relevant neutralino couplings.Comment: 26 pages, LaTeX, 5 eps figures; version to be published in EPJ
Neutralino Production with Polarized Beams in Extended Supersymmetric Models
We discuss associated neutralino production e^+ e^- --> \tilde{\chi}^0_1
\tilde{\chi}^0_2 with both beams polarized in the MSSM, NMSSM and an E_6 model.
It is shown that neutralinos with a large singlino component can be produced at
a high luminosity linear collider in a broad parameter range. Polarization
effects in the extended models are compared over the whole parameter space
where the lightest neutralino is mainly a singlino. We explain the complete
different behavior of these models in some parameter regions, which may help to
identify the respective supersymmetric model.Comment: 10 pages, LaTeX, 10 eps figures, contribution to the Proceedings of
the "2nd Joint ECFA/DESY Study on Physics and Detectors for a Linear
Electron-Positron Collider
Identifying the NMSSM by the interplay of LHC and ILC
The interplay between the LHC and the International Linear Collider
(ILC) with GeV might be crucial for the discrimination between
the minimal and next-to-minimal supersymmetric standard model. We present an
NMSSM scenario, where the light neutralinos have a significant singlino
component, that cannot be distinguished from the MSSM by cross sections and
mass measurements. Mass and mixing state predictions for the heavier
neutralinos from the ILC analysis at different energy stages and comparison
with observation at the LHC, lead to clear identification of the particle
character and identify the underlying supersymmetric model.Comment: 8 pages, 2 eps figures, revtex4 style Contribution to the `2005
International Linear Collider Workshop - Stanford, U.S.A.
Development of a task-level robot programming and simulation system
An ongoing project in developing a Task-Level Robot Programming and Simulation System (TARPS) is discussed. The objective of this approach is to design a generic TARPS that can be used in a variety of applications. Many robotic applications require off-line programming, and a TARPS is very useful in such applications. Task level programming is object centered in that the user specifies tasks to be performed instead of robot paths. Graphics simulation provides greater flexibility and also avoids costly machine setup and possible damage. A TARPS has three major modules: world model, task planner and task simulator. The system architecture, design issues and some preliminary results are given
Chiral selectivity of amino acid adsorption on chiral surfaces - the case of alanine on Pt
We study the binding pattern of the amino acid alanine on the naturally
chiral Pt surfaces Pt(531), Pt(321) and Pt(643). These surfaces are all vicinal
to the {111} direction but have different local environments of their kink
sites and are thus a model for realistic roughened Pt surfaces. Alanine has
only a single methyl group attached to its chiral center, which makes the
number of possible binding conformations computationally tractable.
Additionally, only the amine and carboxyl group are expected to interact
strongly with the Pt substrate. On Pt(531) we study the molecule in its
pristine as well as its deprotonated form and find that the deprotonated one is
more stable by 0.39 eV. Therefore, we study the molecule in its deprotonated
form on Pt(321) and Pt(643). As expected, the oxygen and nitrogen atoms of the
deprotonated molecule provide a local binding "tripod" and the most stable
adsorption configurations optimize the interaction of this "tripod" with
undercoordinated surface atoms. However, the interaction of the methyl group
plays an important role: it induces significant chiral selectivity of about 60
meV on all surfaces. Hereby, the L-enantiomer adsorbs preferentially to the
Pt(321) and Pt(643) surfaces while the D-enantiomer is more stable on
Pt(531). The binding energies increase with increasing surface density of
kink sites, i.e. they are largest for Pt(531) and smallest for Pt(643)
Empirical wind model for the middle and lower atmosphere. Part 1: Local time average
The HWM90 thermospheric wind model was revised in the lower thermosphere and extended into the mesosphere and lower atmosphere to provide a single analytic model for calculating zonal and meridional wind profiles representative of the climatological average for various geophysical conditions. Gradient winds from CIRA-86 plus rocket soundings, incoherent scatter radar, MF radar, and meteor radar provide the data base and are supplemented by previous data driven model summaries. Low-order spherical harmonics and Fourier series are used to describe the major variations throughout the atmosphere including latitude, annual, semiannual, and longitude (stationary wave 1). The model represents a smoothed compromise between the data sources. Although agreement between various data sources is generally good, some systematic differences are noted, particularly near the mesopause. Root mean square differences between data and model are on the order of 15 m/s in the mesosphere and 10 m/s in the stratosphere for zonal wind, and 10 m/s and 4 m/s, respectively, for meridional wind
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