3,331 research outputs found
Launch window analysis of satellites in high eccentricity or large circular orbits
Numerical methods and computer programs for studying the stability and evolution of orbits of large eccentricity are presented. Methods for determining launch windows and target dates are developed. Mathematical models are prepared to analyze the characteristics of specific missions
The roughness of stylolites: Implications of 3D high resolution topography measurements
Stylolites are natural pressure-dissolution surfaces in sedimentary rocks. We
present 3D high resolution measurements at laboratory scales of their complex
roughness. The topography is shown to be described by a self-affine scaling
invariance. At large scales, the Hurst exponent is and
very different from that at small scales where . A
cross-over length scale at around \L_c =1~mm is well characterized.
Measurements are consistent with a Langevin equation that describes the growth
of a stylolitic interface as a competition between stabilizing long range
elastic interactions at large scales or local surface tension effects at small
scales and a destabilizing quenched material disorder.Comment: 4 pages, 4 figure
Logarithmic SUSY electroweak effects on four-fermion processes at TeV energies
We compute the MSSM one-loop contributions to the asymptotic energy behaviour
of fermion-antifermion pair production at future lepton-antilepton colliders.
Besides the conventional logarithms of Renormalization Group origin, extra SUSY
linear logarithmic terms appear of "Sudakov-type". In the TeV range their
overall effect on a variety of observables can be quite relevant and
drastically different from that obtained in the SM case.Comment: 19 pages and 14 figures, corrected version. e-mail:
[email protected]
A single chain analysis of doped quasi one dimensional spin 1 compounds: paramagnetic versus spin 1/2 doping
We present a numerical study of single chain models of doped spin 1
compounds. We use low energy effective one-dimensional models for both the
cases of paramagnetic and spin-1/2 doping. In the case of paramagnetic doping,
the effective model is equivalent to the bond disordered spin-1/2 chain model
recently analyzed by means of real space renormalization group by Hyman and
Yang. By means of exact diagonalizations in the XX limit, we confirm the
stability of the Haldane phase for weak disorder. Above a critical amount of
disorder, the effective model flows to the so called random singlet fixed
point. In the case of spin-1/2 doping, we argue that the Haldane phase should
be destabilized even for weak disorder. This picture is not in contradiction
with existing experimental data. We also discuss the possible occurrence of
(unobserved) antiferromagnetically ordered phases.Comment: 13 pages, 7 included figure
Electroweak supersymmetric effects on high energy unpolarized and polarized single top production at LHC
We consider various processes of single top production at LHC in the
theoretical framework of the MSSM and examine the role of the supersymmetric
electroweak one-loop corrections in a special moderately light SUSY scenario,
in an initial parton-pair c.m. high energy range where a logarithmic asymptotic
expansion of Sudakov type can be used. We show that the electroweak virtual
effects are systematically large, definitely beyond the relative ten percent
size, particularly for a final pair where a special enhancement is
present. We show then in a qualitative way the kind of precision tests of the
model that would be obtainable from accurate measurements of the energy
distributions of the various cross sections and of the top polarization
asymmetries.Comment: 30 pages, 9 figure
Longitudinal Polarization at future Colliders and Virtual New Physics Effects
The theoretical merits of longitudinal polarization asymmetries of
electron-positron annihilation into two final fermions at future colliders are
examined, using a recently proposed theoretical description. A number of
interesting features, valid for searches of virtual effects of new physics, is
underlined, that is reminiscent of analogous properties valid on top of
resonance. As an application to a concrete example, we consider the case of a
model with triple anomalous gauge couplings and show that the additional
information provided by these asymmetries would lead to a drastic reduction of
the allowed domain of the relevant parameters.Comment: 18 pages and 1 figure. e-mail: [email protected]
Associated tW production at LHC: a complete calculation of electroweak supersymmetric effects at one loop
We compute, in the MSSM framework, the total electroweak contributions at one
loop for the process pp -> tW+X, initiated by the parton process bg -> tW. The
supersymmetric effect is analyzed for various choices of the SUSY benchmark
points. Choosing realistic unpolarized and polarized experimental quantities,
we show the size of the various effects and discuss their dependence on the
MSSM parameters.Comment: 32 pages, 9 eps figure
State of the art of plastic sorting and recycling : Feedback to vehicle design
Today car manufacturers are beginning to integrate recycling constraints in the first stages of the design of a new car due to their concern regarding the effects of car design on the recovery of material after End-of-Life Vehicle treatment. Improved understanding of the recycling process can help designers to avoid contaminants in the recycled product and improve the efficiency of current and new sorting methods. The main goal of this paper is to describe the state of the art of the technical efficiency of recovery channels for plastics in Europe in order to define requirements for automotive plastic part design. This paper will first present the results of a survey on industrial and innovative recycling technologies mainly originating from the mining sector, and secondly a simplified methodology for car design integrating plastic recycling constraints. This methodology concerns material association and compatibility, the type of assemblies favourable to better recycling, and better reuse of recycled products in cars.Renault Research Direction FR TCR LAB 1 13, Service 641000-Recycling Engineering, 1 avenue du Golf, 78288 Guyancourt Cedex, Franc
Top quark production at future lepton colliders in the asymptotic regime
The production of a tt(bar) pair from lepton-antilepton annihilation is
considered for values of the center of mass energy much larger than the top
mass, typically of the few TeV size. In this regime a number of simplifications
occurs that allows to derive the leading asymptotic terms of various
observables using the same theoretical description that was used for light
quark production. Explicit examples are shown for the Standard Model and the
Minimal Supersymmetric Standard Model cases.Comment: 20 pages and 13 figures. e-mail: [email protected]
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