13,260 research outputs found
A Silver Anniversary Observation of the X-ray Emitting SN1978K in NGC 1313
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
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
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
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
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
The charged fermion mass matrices are invariant under 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
and mixing. In particular, there is a range of parameters in which
new phases do not contribute to the meson CP violation but give identical
new physics phases in the and 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
The effect of color screening on the formation of a heavy quark-antiquark
() bound state--such as the 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 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
-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
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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