Potential model calculations and predictions for heavy quarkonium

We investigate the spectroscopy and decays of the charmonium and upsilon systems in a potential model consisting of a relativistic kinetic energy term, a linear confining term including its scalar and vector relativistic corrections and the complete perturbative one-loop quantum chromodynamic short distance potential. The masses and wave functions of the various states are obtained using a variational technique, which allows us to compare the results for both perturbative and nonperturbative treatments of the potential. As well as comparing the mass spectra, radiative widths and leptonic widths with the available data, we include a discussion of the errors on the parameters contained in the potential, the effect of mixing on the leptonic widths, the Lorentz nature of the confining potential and the possible $c\bar{c}$ interpretation of recently discovered charmonium-like states.Comment: Physical Review published versio

Surface characterization of selected LDEF tray clamps

The surface characterization of chromic acid anodized 6061-T6 aluminum alloy tray clamps has shown differences in surface chemistry depending upon the position on the Long Duration Exposure Facility (LDEF). Water contact angle results showed no changes in wettability of the tray clamps. The overall surface topography of the control, trailing edge(E3) and leading edge(D9) samples was similar. The thickness of the aluminum oxide layer for all samples determined by Auger depth profiling was less than one micron. X-ray photoelectron spectroscopy (XPS) analysis of the tray clamps showed significant differences in the surface composition. Carbon and silicon containing compounds were the primary contaminants detected

A New Algorithm for Computing Statistics of Weak Lensing by Large-Scale Structure

We describe an efficient algorithm for calculating the statistics of weak lensing by large-scale structure based on a tiled set of independent particle-mesh N-body simulations which telescope in resolution along the line of sight. This efficiency allows us to predict not only the mean properties of lensing observables such as the power spectrum, skewness and kurtosis of the convergence, but also their sampling errors for finite fields of view, which are themselves crucial for assessing the cosmological significance of observations. We find that the nongaussianity of the distribution substantially increases the sampling errors for the skewness and kurtosis in the several to tens of arcminutes regime, whereas those for the power spectrum are only fractionally increased even out to wavenumbers where shot noise from the intrinsic ellipticities of the galaxies will likely dominate the errors.Comment: 12 pages, 13 figures; minor changes reflect accepted versio

Production of pseudoscalar Higgs-bosons in e γe\,\gamma collisions

We investigate the production of a pseudoscalar Higgs-boson $A^0$ using the reaction $e\,\gamma\rightarrow e\,A^0$ at an $e\bar{e}$ collider with center of mass energy of 500 GeV. Supersymmetric contributions are included and provide a substantial enhancement to the cross section for most values of the symmetry breaking parameters. We find that, despite the penalty incurred in converting one of the beams into a source of backscattered photons, the $e\, \gamma$ process is a promising channel for the detection of the $A^0$.Comment: 9 pages RevTex + 2 Postscript figures tar.gzip.uuencode

The Impact of Surface Coal Mining on the Pre- and Post-Mining Agricultural Potential of the Grassland Biome of Southern Africa

Surface mining of coal is widespread in the grassland areas of the Mpumalanga Province in South Africa, and is the main cause of many environmental impacts in this agriculturally important region. To ensure healthy and productive vegetation after the reclamation process, disturbed soils need to be ameliorated and re-vegetated with locally adapted grass species to protect, preserve and improve soils for future agricultural use. To date, soil compaction is regarded as one of the main factors that cause severe restrictions in the effective rooting depth of plants, and the level of compaction is strongly influenced by altered soil water contents, soil texture, soil structure and often non-existing organic matter contents. Imported organic materials and enhanced plant root development may lead to reduced effects of soil compaction and an increased amount of moisture in the soil profile, which becomes available for plant growth during the growing season. This research focussed on the various amelioration aspects to alleviate and mitigate soil compaction to promote sustainable vegetation establishment and production to reinstate the agricultural potential of the disturbed environment. With associated soil amelioration, an increase in biomass production, of selected plant species was noted to be 52% higher on soil that was amended with 40 t/ha of organic amendment, in comparison to the soil that did not receive any. The correct selection of species with a known root structure and basic management requirement has, therefore, the potential to be useful in creating an organically rich, alleviated and more sustainable soil environment to ensure improved rehabilitation results of surface coal mines. It can be concluded, that sufficient data has shown that reclaimed surface coal mine soils can serve as a valuable resource to the animal production industry as well as to local communities, if managed correctly

Potential model calculations and predictions for csˉ\bm c\bar{\bm s} quarkonia

We investigate the spectroscopy and decays of the charm-strange quarkonium system in a potential model consisting of a relativistic kinetic energy term, a linear confining term including its scalar and vector relativistic corrections and the complete perturbative one-loop quantum chromodynamic short distance potential. The masses and wave functions of the various states are obtained using a variational technique, which are then used in a perturbative treatment of the potential to find the mass spectrum of the $c\bar{s}$ system and radiative decay widths. Our results compare well with the available data for the spectrum of $D_s$ states. We include a discussion of the effect of mixing and an investigation of the Lorentz nature of the confining potential.Comment: 6 pages 3 Table