32,994 research outputs found

    Recent results using all-point quark propagators

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    Pseudofermion methods for extracting all-point quark propagators are reviewed, with special emphasis on techniques for reducing or eliminating autocorrelations induced by low eigenmodes of the quark Dirac operator. Recent applications, including high statistics evaluations of hadronic current correlators and the pion form factor, are also described.Comment: LateX, 3 pages, 6 eps figures, Lattice2002(algor), corrected some typo

    Unquenched Studies Using the Truncated Determinant Algorithm

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    A truncated determinant algorithm is used to study the physical effects of the quark eigenmodes associated with eigenvalues below 420 MeV. This initial high statistics study focuses on coarse (646^4) lattices (with O(a2a^2) improved gauge action), light internal quark masses and large physical volumes. Three features of full QCD are examined: topological charge distributions, string breaking as observed in the static energy and the eta prime mass.Comment: Lattice2001(confinement); 3pgs(Latex), 4figs.(ps

    Physical Effects of Infrared Quark Eigenmodes in LQCD

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    A truncated determinant algorithm is used to study the physical effects of the quark eigenmodes associated with eigenvalues below 400 MeV. This initial study focuses on coarse lattices (with O(a^2) improved gauge action), light internal quark masses and large physical volumes. Four bellwether full QCD processes are discussed: topological charge distributions, the eta prime propagator, string breaking as observed in the static energy and the rho decay into two pions.Comment: LATTICE99(Confinement); 3pgs(Latex), 4figs.(eps

    Hadronic Correlators from All-point Quark Propagators

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    A method for computing all-point quark propagators is applied to a variety of processes of physical interest in lattice QCD. The method allows, for example, efficient calculation of disconnected parts and full momentum-space 2 and 3 point functions. Examples discussed include: extraction of chiral Lagrangian parameters from current correlators, the pion form factor, and the unquenched eta-prime.Comment: LATTICE01(Algorithms and Machines

    Key Components and Best Practices for Environmental Impact Assessments

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    New and emerging activities pose risks to the conservation and sustainable development of ABNJ in the absence of prior assessment, and remain a significant gap under UNCLOS. Environmental impact assessments and strategic environmental assessments are widely accepted as valuable tools for incorporating environmental and social concerns into decision making processes with respect to specific projects or activities (EIAs) or policies, plans or programmes (SEAs). The development of a new international instrument to address the conservation and sustainable use of marine biological diversity in areas beyond national jurisdiction ("international Instrument") is an opportunity to incorporate best practices for EIAs and SEAs already found under a number of multilateral and regional agreements, and apply lessons learned from their application. Importantly, the new Instrument should also provide the mechanism for the assessment of cumulative impacts of activities and climate change

    City strategy : final evaluation

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    The City Strategy (CS) concept was first announced in the 2006 Welfare Reform Green Paper – A new deal for welfare: Empowering people to work. CS was designed at a time of growth in the national economy to combat enduring pockets of entrenched worklessness and poverty in urban areas by empowering local institutions to come together in partnerships to develop locally sensitive solutions. It was premised on the idea that developing a better understanding of the local welfare to work arena would allow partnerships to align and pool funding and resources to reduce duplication of services and fill gaps in provision. The ‘theory of change’ underlying CS suggested that such an approach would result in more coordinated services which would be able to generate extra positive outcomes in terms of getting people into jobs and sustaining them in employment over and above existing provision. CS was initially set to run for two years from April 2007 to March 2009 in 15 CS Pathfinder (CSP) areas, varying in size from five wards in one town through single local authority areas to subregional groupings of multiple local authority areas, across Great Britain. In July 2008, the Secretary of State for Work and Pensions announced an extension for a further two years to March 2011. In April 2009, two local areas in Wales, which were in receipt of monies from the Deprived Areas Fund (DAF), were invited by the Department for Work and Pensions (DWP) to form local partnerships with a similar remit to the CSPs, albeit more limited in scope – to develop locally sensitive solutions to economic inactivity, to the CSPs. During the period that the CS initiative was operational, economic conditions changed markedly with a severe recession, followed by fragile recovery. The CSPs had to cope with ongoing changes in policy throughout the lifetime of the CS initiative, including a General Election and a new Coalition Government at Westminster early in the fourth year. While policy changes are a fact of life for local practitioners operating in the welfare to work arena, the global recession in 2008/09 marked a fundamental change in the context in which local partnerships operated

    Heavy-Light Wavefunctions in Lattice QCD

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    Using a multistate smearing method, Coulomb gauge wave functions of heavy-light mesons are studied in lattice QCD. Wave functions for the ground state, the first radially excited S-wave state, and the lowest P-wave states of a heavy-light meson are calculated in quenched approximation. The results are found to be in remarkably good agreement with the predictions of a simple relativistic quark model.Comment: Latex file inputs psfig.tex, and espcrc2.sty, 3 figures in uuencoded fil

    String Breaking in Four Dimensional Lattice QCD

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    Virtual quark pair screening leads to breaking of the string between fundamental representation quarks in QCD. For unquenched four dimensional lattice QCD, this (so far elusive) phenomenon is studied using the recently developed truncated determinant algorithm (TDA). The dynamical configurations were generated on an Athlon 650 MHz PC. Quark eigenmodes up to 420 MeV are included exactly in these TDA studies performed at low quark mass on large coarse (but O(a2a^2) improved) lattices. A study of Wilson line correlators in Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical configurations reveals evidence for flattening of the string tension at distances R ≥\geq approximately 1 fm.Comment: 16 pages, 5 figures, Latex (deleted extraneous eps figure file

    Electromagnetic Structure of Light Baryons in Lattice QCD

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    A method in which electromagnetic properties of hadrons are studied by direct simulation of dynamical photon effects is applied to the extraction of the isomultiplet structure of the octet baryons. Using 187 configurations at β=5.7\beta=5.7 with Wilson action, and up and down quark masses determined from the meson spectrum, the nucleon splitting is found to be 1.55(±0.56  stat)1.55(\pm 0.56\; \rm stat) MeV; the hyperon splittings are found to be Σ0−Σ+=2.47±0.39\Sigma^{0}-\Sigma^{+}=2.47\pm 0.39, Σ−−Σ0=4.63±0.36\Sigma^{-}-\Sigma^{0}=4.63\pm 0.36, Ξ−−Ξ0=5.68±0.24\Xi^{-}-\Xi^{0}=5.68\pm 0.24 MeV. Estimated systematic corrections arising from finite volume and the quenched approximation are included in these results.Comment: Talk presented at LATTICE96(phenomenology
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