2,511 research outputs found

    Launch window analysis of satellites in high eccentricity or large circular orbits

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    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

    Longitudinal Polarization at future e+e−e^+e^- Colliders and Virtual New Physics Effects

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    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 ZZ 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]

    Photonic crystal thin films of GaAs prepared by atomic layer deposition

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    Photonic crystal thin films were fabricated via the self-assembly of a lattice of silica spheres on silicon (100) substrates. Progressive infilling of the air spaces within the structure with GaAs was achieved using trimethylgallium and arsine under atomic-layer-deposition conditions. Samples with the highest levels of GaAs infill were subsequently inverted using selective etching. Reflectance spectra are interpreted via the Bragg expression and calculated photonic band structure diagrams. For GaAs infilled and inverted samples, the relative positions of the first and second order Bragg reflections are strongly influenced by the wavelength dependent refractive index

    Single production of excited electrons at future e^-e^+, ep and pp colliders

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    We analyzed the potential of the LC with s=0.5\sqrt{s}=0.5 TeV, LC×\timesLHC based ep collider with s=3.74\sqrt{s}=3.74 TeV and LHC with s=14\sqrt{s}=14 TeV to search for excited electrons through transition magnetic type couplings with gauge bosons. The e⋆→eγe^{\star}\to e\gamma signal and corresponding backgrounds are studied in detail.Comment: 11 pages, 11 figures, 3 table

    Electroweak supersymmetric effects on high energy unpolarized and polarized single top production at LHC

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    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 tH−tH^- 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

    Associated tW production at LHC: a complete calculation of electroweak supersymmetric effects at one loop

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    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

    Weak Interaction Sum Rules for Polarized top-antitop Production at LHC

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    We consider two polarization asymmetries in the process of top-antitop production at LHC. We show that the theoretical predictions for these two quantities, at the strong and electroweak partonic one-loop level, are free of QCD and QED effects. At this perturbative level we derive two sum rules, that relate measurable quantities of top-antitop production to genuinely weak inputs. This would allow to perform two independent tests of the candidate theoretical model, with a precision that will be fixed by the future experimental accuracies of the different polarization measurements. A tentative quantitative illustration of this statement for a specific MSSM scenario is enclosed, and a generalization to include two other future realistic measurements is also proposed.Comment: 13 pages, 3 figures, local report number adde

    Probing the Weak Boson Sector in γe→Ze\gamma e\rightarrow Ze

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    We study possible deviations from the standard model in the reaction γe→Ze\gamma e\rightarrow Ze at a 500 GeV e+e−e^+e^- collider. As a photon source we use a laser backscattered photon beam. We investigate the most general γZγ\gamma Z\gamma and γZZ\gamma ZZ vertices including operators up to energy-dimension-six which are Lorentz invariant. These vertices require four extra parameters; two are CP-conserving, h1γh^\gamma_1 and h1Zh^Z_1, and two are CP-violating, h2γh^\gamma_2 and h2Zh^Z_2. We present analytical expressions of the helicity amplitudes for the process γe→Ze\gamma e\rightarrow Ze for arbitrary values of anomalous couplings. Assuming Standard Model values are actually measured we present the allowed region in the (h1γ,h1Zh^\gamma_1,h^Z_1) plane at the 90\% confidence level. We then show how the angular correlation of the ZZ decay products can be used to extract detailed information on the anomalous (especially CP-violating) γZγ\gamma Z\gamma and γZZ\gamma ZZ couplings.Comment: Latex, 25 pages, 12 figures (not included). One compressed postscript file including all the figures available at ftp://ftp.kek.jp/kek/preprints/TH/TH-420/kekth420.ps.g

    Chirurgie bij patiënten met een heupfractuur, redenen voor een uitgestelde operatie

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