The Scalar Quarkonium Spectrum and Quarkonium-Glueball Mixing

We evaluate the valence approximation to the mass of scalar quarkonium and to the mixing energy between scalar quarkonium and the lightest scalar glueball for a range of different lattice sizes and quark masses. Our results support the identification of $f_0(1710)$ as the lightest scalar glueball.Comment: 3 pages, 4 PostScript figures, talk given at Lattice 9

Coupling Constants for Scalar Glueball Decay

We evaluate the partial decay widths of the lightest scalar glueball to pairs of pseudoscalar quark-antiquark states. The calculation is done in the valence (quenched) approximation on a 16^3 \time 24 lattice at $\beta = 5.7$. These predictions and values obtained earlier for the infinite volume continuum limit of the scalar glueball's mass are in good agreement with the observed properties of $f_J(1710)$ and inconsistent with all other observed meson resonances.Comment: 8 pages of Latex, 12 PostScript figures, 2 macros included, plenary talk given by D. Weingarten at Lattice 95, to appear in conference proceeding

Fluxon-induced losses in niobium thin-film cavities revisited

Long standing data from niobium thin film accelerating cavities will be revisited and analysed by a modified London model of RF superconductivity. Firstly, the applicability of this model is explored using data of the BCS surface resistance and its dependence on the RF magnetic field, temperature and mean free path. Secondly, the RF losses from trapped magnetic flux are analysed with regard to their dependence on these same parameters

Meson Decay Constants from the Valence Approximation to Lattice QCD

We evaluate $f_{\pi}/ m_{\rho}$, $f_K/ m_{\rho}$, $1/f_{\rho}$, and $m_{\phi}/(f_{\phi} m_{\rho})$, extrapolated to physical quark mass, zero lattice spacing and infinite volume, for lattice QCD with Wilson quarks in the valence (quenched) approximation. The predicted ratios differ from experiment by amounts ranging from 12\% to 17\% equivalent to between 0.9 and 2.8 times the corresponding statistical uncertainties.Comment: uufiles encoded copy of 40 page Latex article, including 14 figures in Postscript. The long version of hep-lat/9302012, IBM/HET 93-

Hadron Masses from the Valence Approximation to Lattice QCD

We evaluate pseudoscalar, vector, spin 1/2 and spin 3/2 baryon masses predicted by lattice QCD with Wilson quarks in the valence (quenched) approximation for a range of different values of lattice spacing, lattice volume and quark mass. Extrapolating these results to physical quark mass, then to zero lattice spacing and infinite volume we obtain values for eight mass ratios. We also determine the zero lattice spacing, infinite volume limit of an alternate set of five quantities found without extrapolation in quark mass. Both sets of predictions differ from the corresponding observed values by amounts consistent with the predicted quantities' statistical uncertainties.Comment: 108 pages of Latex, including 50 PostScript figures, tarred, compressed and uuencoded. IBM-HET-94-3. (The first version of this posting exceeded the size limit. I squeezed the second version in by dropping out the figues. This version gets the figures in but has to be run through Latex and dvips.

Agri-environmental policy in Germany: soil and water conservation

This paper is concerned with agri-environmental policy in Germany and focuses in particular on soil and water conservation. At first it discusses to what extent agriculture contributes to erosion and the pollution of surface waters and groundwater with nutrients and pesticides. Whereas erosion is a minor problem in Germany water pollution due to modern and intensive agriculture is of major concern. In theory, a broad range of environmental policy instruments exists. In practice, agri-environmental policy in Germany is dominated by command-and-control-measures, whereas incentivebased measures are of minor importance. In this paper recent developments of the most important legal and institutional settings concerning soil and water conservation policies are surveyed with special emphasis on the Federal Water Act and the Implementation of the EU Nitrate Directive into German legislation by the Fertilizer Ordinance. Since the Common Agricultural Policy (CAP) of the EU heavily affects farm structure, production intensity and regional specialization in agriculture, agri-environmental issues cannot be discussed without taking into account agricultural policy. Hence, the paper argues, that for different reasons the CAP is likely to become more environmentally friendly in future. Furthermore, impacts of alternative water conservation policies are investigated by using a regionalized agricultural sector model. Information obtained by the model analysis cover the development of nitrogen balances, potential nitrate concentrations in the soil percolation water, potentially resulting costs and effects on the agricultural incomes in the former FRG on the county level. -- G E R M A N V E R S I O N: Im ersten Teil dieses Beitrages über Agrarumweltpolitik in Deutschland im Bereich des Bodenund Gewässerschutzes wird ein Überblick über den landwirtschaftlich bedingten Bodenabtrag und die Belastung von Oberflächengewässern und Grundwasser mit Nährstoffen und Pflanzenschutzmitteln gegeben. Während Erosion in Deutschland von geringer Relevanz ist, kommt der durch eine moderne und intensiv betriebene Landwirtschaft verursachten Gewässerverschmutzung eine erheblich größere Bedeutung zu. In der umweltökonomischen Theorie existiert eine Reihe von umweltpolitischen Instrumenten. In der Praxis wird die Umweltpolitik in Deutschland von Ge- und Verboten geprägt, während anreizorientierte Maßnahmen nur selten eingesetzt werden. Der Artikel untersucht die wichtigsten rechtlichen und institutionellen Rahmenbedingungen im Bereich der Boden- und Gewässerschutzpolitik, wobei das Schwergewicht auf dem Wasserhaushaltsgesetz und der Düngeverordnung liegt, mit der die EU-Nitratrichtlinie in deutsches Recht umgesetzt wird. Da die Gemeinsame Agrarpolitik der EU (GAP) die Betriebsstruktur, Produktionsintensität und die regionale Spezialisierung der Landwirtschaft beeinflußt, können Agrarumweltfragen nicht diskutiert werden, ohne die Agrarpolitik zu berücksichtigen. Aus verschiedenen Gründen ist es wahrscheinlich, daß die GAP in Zukunft etwas umweltfreundlicher gestaltet wird. Mit Hilfe eines regionalisierten Agrarsektormodells werden die Auswirkungen alternativer Grundwasserschutzstrategien analysiert. Die Modellergebnisse erlauben für die alten Bundesländer Deutschlands auf der Ebene der Landkreise Aussagen über die Entwicklung von Stickstoffbilanzen, potentiellen Nitratkonzentrationen im neugebildeten Grundwasser, hierdurch potentiell hervorgerufene Kosten und Auswirkungen auf die Einkommen in der Landwirtschaft.