11,667 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

    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

    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

    CP asymmetries at D0

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    Using two independent measurements of the semileptonic CP asymmetry in the BsB_s system, we constrain the CP violating phase of the BsB_s system to be ϕs=0.700.39+0.47\phi_s = -0.70^{+0.47}_{-0.39}. The data sample corresponds to an integrated luminosity of 1.1 fb1^{-1} accumulated with D0 detector at the Fermilab Tevatron collider. We also measure the direct CP violating asymmetry in the decay B+J/ψK+B^+ \to J/\psi K^+ to be ACP(B+J/ψK+)=+0.0067±0.0074A_{CP}(B^+ \to J/\psi K^+) = +0.0067 \pm 0.0074(stat)±0.0026\pm0.0026(syst). The data corresponds to an integrated luminosity of 1.6 fb1^{-1}.Comment: contributed paper to EPS07, Manchester, UK, manuscript number EPSHEPP17

    Quantum Mechanics of the Vacuum State in Two-Dimensional QCD with Adjoint Fermions

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    A study of two-dimensional QCD on a spatial circle with Majorana fermions in the adjoint representation of the gauge groups SU(2) and SU(3) has been performed. The main emphasis is put on the symmetry properties related to the homotopically non-trivial gauge transformations and the discrete axial symmetry of this model. Within a gauge fixed canonical framework, the delicate interplay of topology on the one hand and Jacobians and boundary conditions arising in the course of resolving Gauss's law on the other hand is exhibited. As a result, a consistent description of the residual ZNZ_N gauge symmetry (for SU(N)) and the ``axial anomaly" emerges. For illustrative purposes, the vacuum of the model is determined analytically in the limit of a small circle. There, the Born-Oppenheimer approximation is justified and reduces the vacuum problem to simple quantum mechanics. The issue of fermion condensates is addressed and residual discrepancies with other approaches are pointed out.Comment: 44 pages; for hardcopies of figures, contact [email protected]

    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,

    GENERIC ADVERTISING WEAROUT: THE CASE OF THE NEW YORK CITY FLUID MILK CAMPAIGN

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    This article examines two major generic fluid milk advertising campaigns in New York City during the 1986-92 period. Estimates from a time-varying parameter model show that the evolution of the impact of generic advertising on fluid milk sales over each campaign followed a bell-shaped pattern. Results also show that the first campaign was effective for twice as long as the second campaign and that it has a higher peak and higher average advertising elasticity. These findings may reflect long-term generic milk advertising wearout in the New York City market.Marketing,

    Remarks on Bodenmillers theorem

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    Transverse QCD Dynamics Near the Light Cone

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    Starting from the QCD Hamiltonian in near-light cone coordinates, we study the dynamics of the gluonic zero modes. Euclidean 2+1 dimensional lattice simulations show that the gap at strong coupling vanishes at intermediate coupling. This result opens the possibility to synchronize the continuum limit with the approach to the light cone.Comment: 15 pages, LaTeX, 3 figures (7 PS files
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