12,866 research outputs found

    A Silver Anniversary Observation of the X-ray Emitting SN1978K in NGC 1313

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    We describe the results of a 2003 Chandra ACIS-I observation of SN1978K. The spectrum shows little flux below 0.6 keV, in contrast to the 2002 ACIS-S observation that showed flux to 0.4 keV. Fitting the ACIS-I spectrum alone leads to two solutions depending upon the value of the column density. A joint fit using a dual thermal plasma model applied to the ACIS-I and a contemporaneous XMM spectrum, which if fit alone also leads to a two-column solution, yields a single column density fit. The fitted temperature of the joint fit for the soft component remains constant with the errors from previous Chandra, XMM, and ASCA data. The hard temperature recovers from its 2000-2002 decline and corresponds to an increase in the column density during that time. The hard (2-10 keV) light curve is confirmed to be declining. The derived number density represents a lower limit of 1e5 depending upon the adopted filling factor of the emitting volume, leading to an estimated mass cooling rate of 0.1-0.15 solar masses per year.Comment: accepted A

    Signatures of Confinement in Axial Gauge QCD

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    A comparative dynamical study of axial gauge QED and QCD is presented. Elementary excitations associated with particular field configurations are investigated. Gluonic excitations analogous to linearly polarized photons are shown to acquire infinite energy. Suppression of this class of excitations in QCD results from quantization of the chromelectric flux and is interpreted as a dual Meissner effect, i.e. as expulsion from the QCD vacuum of chromo-electric fields which are constant over significant distances. This interpretation is supported by a comparative evaluation of the interaction energy of static charges in the axial gauge representation of QED and QCD.Comment: 22 pages (no figures

    Analysis of light scattering off photonic crystal slabs in terms of Feshbach resonances

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    Techniques to deal with Feshbach resonances are applied to describe resonant light scattering off one dimensional photonic crystal slabs. Accurate expressions for scattering amplitudes, free of any fitting parameter, are obtained for isolated as well as overlapping resonances. They relate the resonance properties to the properties of the optical structure and of the incident light. For the most common case of a piecewise constant dielectric function, the calculations can be carried out essentially analytically. After establishing the accuracy of this approach we demonstrate its potential in the analysis of the reflection coefficients for the diverse shapes of overlapping, interacting resonances.Comment: 12 pages, 5 figure

    Scaling Invariance in a Time-Dependent Elliptical Billiard

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    We study some dynamical properties of a classical time-dependent elliptical billiard. We consider periodically moving boundary and collisions between the particle and the boundary are assumed to be elastic. Our results confirm that although the static elliptical billiard is an integrable system, after to introduce time-dependent perturbation on the boundary the unlimited energy growth is observed. The behaviour of the average velocity is described using scaling arguments

    Fast talk & flush times : the confidence man as a literary convention

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    Includes bibliographical references (pages 221-232) and index.Lenz provides a historical overview of the American confidence man, and its role as a literary convention.The new country -- The early tradition of confidence games -- The emergence of the confidence-man convention -- Four variations of the confidence man -- The war, Mark Twain, and the flush-times confidence man -- From the new country to the twentieth century.Digitized at the University of Missouri--Columbia MU Libraries Digitization Lab in 2012. Digitized at 600 dpi with Zeutschel, OS 15000 scanner. Access copy, available in MOspace, is 400 dpi, grayscale

    Implications of CP violating 2HDM in B physics

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    The charged fermion mass matrices are invariant under U(1)3U(1)^3 symmetry linked to the fermion number transformation. Under the condition that the definition of this symmetry in arbitrary weak basis does not depend upon Higgs parameters such as ratio of vacuum expectation values, a class of two Higgs doublet models (2HDM) can be identified in which tree level flavor changing neutral currents normally present in 2HDM are absent. However unlike the type I or type II Higgs doublet models, the charged Higgs couplings in these models contain additional flavor dependent CP violating phases. These phases can account for the recent hints of the beyond standard model CP violation in the BdB_d and BsB_s mixing. In particular, there is a range of parameters in which new phases do not contribute to the KK meson CP violation but give identical new physics phases in the BdB_d and BsB_s meson mixing.Comment: 7 pages, 1 figure, Talk given by Bhavik P. Kodrani at 16th International Symposium on Particles, Strings and Cosmology, July 19th - 23rd, 2010, Valencia, Spai

    Color screening in a constituent quark model of hadronic matter

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    The effect of color screening on the formation of a heavy quark-antiquark (QQˉQ\bar{Q}) bound state--such as the J/ψJ/\psi meson--is studied using a constituent-quark model. The response of the nuclear medium to the addition of two color charges is simulated directly in terms of its quark constituents via a string-flip potential that allows for quark confinement within hadrons yet enables the hadrons to separate without generating unphysical long-range forces. Medium modifications to the properties of the heavy meson, such as its energy and its mean-square radius, are extracted by solving Schr\"odinger's equation for the QQˉQ\bar{Q} pair in the presence of a (screened) density-dependent potential. The density dependence of the heavy-quark potential is in qualitative agreement with earlier studies of its temperature dependence extracted from lattice calculations at finite temperature. In the present model it is confirmed that abrupt changes in the properties of the J/ψJ/\psi-meson in the hadronic medium ({\it plasma}), correlate strongly with the deconfining phase transition.Comment: 7 pages, 3 figures, submitted to PRC for publication, uses revtex

    AN ANALYSIS OF U.S. DAIRY POLICY DEREGULATION USING AN IMPERFECT COMPETITION MODEL

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    An imperfect competition model of the U.S. milk market is developed for analyzing the impacts of dairy policy deregulation. Estimated degree-of-competition parameters indicate that the U.S. milk market has become more competitive over time. The usefulness of the model is demonstrated by showing the relative differences of dynamic simulation results of the imperfect competition model with the results of a conventional exogenous fluid differential model.Agricultural and Food Policy,
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