8,073 research outputs found

    Hyperon masses in nuclear matter

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    We analyze hyperon and nucleon mass shifts in nuclear matter using chiral perturbation theory. Expressions for the mass shifts that include strong interaction effects at leading order in the density are derived. Corrections to our results are suppressed by powers of the Fermi momentum divided by either the chiral symmetry breaking scale or the nucleon mass. Our work is relevant for neutron stars and for large hypernuclei

    A New Expansion for Nucleon-Nucleon Interactions

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    We introduce a new and well defined power counting for the effective field theory describing nucleon-nucleon interactions. Because of the large NN scattering lengths it differs from other applications of chiral perturbation theory and is facilitated by introducing an unusual subtraction scheme and renormalization group analysis. Calculation to subleading order in the expansion can be done analytically, and we present the results for both the 1S0 and 3S1-3D1 channels.Comment: 10 pages, 3 figures, latex. Corrected typo, small change to tex

    Online Gaming Can Make a Better World: Jane McGonigal

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    With personal feelings put aside and sociological theoretical depictions brought to the forefront, it is interesting to compare some of Jane\u27s ideas with that of both Emile Durkheim and Max Weber. The theorist who stood out right away, being exemplified through Jane\u27s positive attitude claims on a much larger, macro-level scale, was Emile Durkheim. Jane\u27s ideas about transcending human\u27s as a resource through the social fabrics of gaming into something that might solve world hunger, poverty, and global warming was nothing short of functionalism at it\u27s best. Jane\u27s platform for social structure and maintaining positive social order is the online world, and online gaming is the vehicle for change

    Research related to measurements of atomic species in the earth's upper atmosphere Final report

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    Interaction kinetics of atomic oxygen and hydrogen on metal surfaces of satellite-borne mass spectrometer

    Investigation of atomic oxygen-surface interactions related to measurements with dual air density explorer satellites

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    For a number of candidate materials of construction for the dual air density explorer satellites the rate of oxygen atom loss by adsorption, surface reaction, and recombination was determined as a function of surface and temperature. Plain aluminum and anodized aluminum surfaces exhibit a collisional atom loss probability alpha .01 in the temperature range 140 - 360 K, and an initial sticking probability. For SiO coated aluminum in the same temperature range, alpha .001 and So .001. Atom-loss on gold is relatively rapid alpha .01. The So for gold varies between 0.25 and unity in the temperature range 360 - 140 K

    Minimal Extension of the Standard Model Scalar Sector

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    The minimal extension of the scalar sector of the standard model contains an additional real scalar field with no gauge quantum numbers. Such a field does not couple to the quarks and leptons directly but rather through its mixing with the standard model Higgs field. We examine the phenomenology of this model focusing on the region of parameter space where the new scalar particle is significantly lighter than the usual Higgs scalar and has small mixing with it. In this region of parameter space most of the properties of the additional scalar particle are independent of the details of the scalar potential. Furthermore the properties of the scalar that is mostly the standard model Higgs can be drastically modified since its dominant branching ratio may be to a pair of the new lighter scalars.Comment: 4 pages, 2 figure
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