4,023 research outputs found

    Correlations of πN\boldsymbol{\pi N} Partial Waves for Multi-Reaction Analyses

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    In the search for missing baryonic resonances, many analyses include data from a variety of pion- and photon-induced reactions. For elastic πN\pi N scattering, however, usually the partial waves of the SAID or other groups are fitted, instead of data. We provide the partial-wave covariance matrices needed to perform correlated χ2\chi^2 fits, in which the obtained χ2\chi^2 equals the actual χ2\chi^2 up non-linear and normalization corrections. For any analysis relying on partial waves extracted from elastic pion scattering, this is a prerequisite to assess the significance of resonance signals and to assign any uncertainty on results. The influence of systematic errors is also considered.Comment: 7 pages, 3 figures; Acknowledgements update

    Sensitivity to the pion-nucleon coupling constant in partial-wave analyses of elastic pi-N and NN scattering and pion photoproduction

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    We summarize results obtained in our studies of the pion-nucleon coupling constant. Several different techniques have been applied to pi-N and NN elastic scattering data, and the existing database for single-pion photoproduction. The most reliable determination comes from pi-N elastic scattering. The sensitivity in this reaction was found to be greater, by at least a factor of 3, when compared with analyses of NN elastic scattering or single-pion photoproduction.Comment: 10 pages, 1 figure. Talk given at the Uppsala workshop on the pion-nucleon coupling constan

    New Jersey\u27s school funding policy from 2002 to the present and its impact on student achievement

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    The purpose of the study was to identify how school districts were impacted by the state aid decisions made from 2002 and to then determine if there was a relationship between the excess or shortfall of state aid received and the achievement of students in each district during the same period as measured by standards used to identify schools in need of improvement. The study included 540 non-Abbott school districts and considered enrollment growth, change in total budget, and change in state aid. It used the 2004-2005 report of schools in need of improvement to identify districts that were failing to achieve. As more years passed from the 2001-2002 base year, the last year in which actual district enrollments were used to calculate the state aid to be received by each district, there was a greater disparity in the amount of state aid received by the school districts in terms of changes in district enrollments. At the same time, more districts were being identified as having schools in need of improvement. No direct causal relationship was identified, however parallels were identified that warrant further study

    A Rosetta Stone Relating Conventions In Photo-Meson Partial Wave Analyses

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    A new generation of complete experiments in pseudoscalar meson photo-production is being pursued at several laboratories. While new data are emerging, there is some confusion regarding definitions of asymmetries and the conventions used in partial wave analyses (PWA). We present expressions for constructing asymmetries as coordinate-system independent ratios of cross sections, along with the names used for these ratios by different PWA groups. (This update reflects a recent change in the definition of an asymmetry as used by one group.)Comment: v2: This update reflects a recent change in the definition of an asymmetry as used by one PWA group -see Table 1. v1: 4 pages. Contribution to the proceedings of the 8th International Workshop on the Physics of Excited Nucleons (NSTAR2011), Newport News, VA, USA, May 17-20, 201

    Fast Shocks From Magnetic Reconnection Outflows

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    Magnetic reconnection is commonly perceived to drive flow and particle acceleration in flares of solar, stellar, and astrophysical disk coronae but the relative roles of different acceleration mecha- nisms in a given reconnection environment are not well understood. We show via direct numerical simulations that reconnection outflows produce weak fast shocks, when conditions for fast recon- nection are met and the outflows encounter an obstacle. The associated compression ratios lead to a Fermi acceleration particle spectrum that is significantly steeper than the strong fast shocks commonly studied, but consistent with the demands of solar flares. While this is not the only acceleration mechanism operating in a reconnection environment, it is plausibly a ubiquitous one

    Effect of thermodynamics on ion mixing

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    Ion mixing of elemental 4d-5d metallic bilayers at 77 K by 600 keV Xe + + ions has been studied to test the validity of the phenomenological model of ion mixing that predicts a dependence on the chemical heats of mixing, DeltaHmix, and on the cohesive energies, DeltaHcoh, of the bilayer elements. A series of samples was chosen to minimize the variation in kinematical properties between samples while maximizing the variation in heats of mixing. The experimental results agree well with the model's predictions, and the experimentally determined constants K1=0.034 Ã… and K2=27 agree with those of previous work
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