4,152 research outputs found
Pion dissociation and Levinson's theorem in hot PNJL quark matter
Pion dissociation by the Mott effect in quark plasma is described within the
generalized Beth-Uhlenbeck approach on the basis of the PNJL model which allows
for a unified description of bound, resonant and scattering states. As a first
approximation, we utilize the Breit-Wigner ansatz for the spectral function and
clarify its relation to the complex mass pole solution of the pion
Bethe-Salpeter equation. Application of the Levinson theorem proves that
describing the pion Mott dissociation solely by means of spectral broadening of
the pion bound state beyond T_Mott leaves out a significant aspect. Thus we
acknowledge the importance of the continuum of scattering states and show its
role for the thermodynamics of pion dissociation.Comment: 18 pages, 6 figure
The Politics of Denying Communion to Catholic Elected Officials
Publisher's version made available in accordance with the publisher's policy.In his 2004 presidential campaign, John Kerry, a Catholic, was threatened with being denied Holy Communion because of his pro-choice voting record. This article investigates the extent to which communion denial impacted Catholic elected officials and analyzes public attitudes regarding communion denial for Kerry. The results of our analysis suggest that, despite heavy media coverage, few bishops endorsed the communion denial and few pro-choice Catholic officials were threatened. While the data also indicate there are meaningful political implications for public attitudes on communion denial, the tactic does not command support from many Catholics
Non-Gaussian statistics of electrostatic fluctuations of hydration shells
We report the statistics of electric field fluctuations produced by SPC/E
water inside a Kihara solute given as a hard-sphere core with a Lennard-Jones
layer at its surface. The statistics of electric field fluctuations, obtained
from numerical simulations, are studied as a function of the magnitude of a
point dipole placed close to the solute-water interface. The free energy
surface as a function of the electric field projected on the dipole direction
shows a cross-over with the increasing dipole magnitude. While it is a
single-well harmonic function at low dipole values, it becomes a double-well
surface at intermediate dipole moment magnitudes, transforming to a single-well
surface, with a non-zero minimum position, at still higher dipoles. A broad
intermediate region where the interfacial waters fluctuate between the two
minima is characterized by intense field fluctuations, with non-Gaussian
statistics and the variance far exceeding the linear-response expectations. The
excited state of the surface water is found to be lifted above the ground state
by the energy required to break approximately two hydrogen bonds. This state is
pulled down in energy by the external electric field of the solute dipole,
making it readily accessible to thermal excitations. The excited state is a
localized surface defect in the hydrogen-bond network creating a stress in the
nearby network, but otherwise relatively localized in the region closest to the
solute dipole
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