14,955 research outputs found
Cauchy-characteristic Evolution of Einstein-Klein-Gordon Systems: The Black Hole Regime
The Cauchy+characteristic matching (CCM) problem for the scalar wave equation
is investigated in the background geometry of a Schwarzschild black hole.
Previously reported work developed the CCM framework for the coupled
Einstein-Klein-Gordon system of equations, assuming a regular center of
symmetry. Here, the time evolution after the formation of a black hole is
pursued, using a CCM formulation of the governing equations perturbed around
the Schwarzschild background. An extension of the matching scheme allows for
arbitrary matching boundary motion across the coordinate grid. As a proof of
concept, the late time behavior of the dynamics of the scalar field is
explored. The power-law tails in both the time-like and null infinity limits
are verified.Comment: To appear in Phys. Rev. D, 9 pages, revtex, 5 figures available at
http://www.astro.psu.edu/users/nr/preprints.htm
Aspects of open-flavour mesons in a comprehensive DSBSE study
Open-flavour meson studies are the necessary completion to any comprehensive
investigation of quarkonia. We extend recent studies of quarkonia in the
Dyson-Schwinger-Bethe-Salpeter-equation approach to explore their results for
all possible flavour combinations. Within the inherent limitations of the
setup, we present the most comprehensive results for meson masses and leptonic
decay constants currently available and put them in perspective with respect to
experiment and other approaches.Comment: 38 pages, 26 figures, 2 tables, revised according to reviewer
comment
The electro production of d* dibaryon
dibaryon study is a critical test of hadron interaction models. The
electro production cross sections of have been calculated based on
the meson exchange current model and the cross section around 30 degree of 1
GeV electron in the laboratory frame is about 10 nb. The implication of this
result for the dibaryon search has been discussed.Comment: 12 pages, 12 figures, Late
Einstein boundary conditions for the Einstein equations in the conformal-traceless decomposition
In relation to the BSSN formulation of the Einstein equations, we write down
the boundary conditions that result from the vanishing of the projection of the
Einstein tensor normally to a timelike hypersurface. Furthermore, by setting up
a well-posed system of propagation equations for the constraints, we show
explicitly that there are three constraints that are incoming at the boundary
surface and that the boundary equations are linearly related to them. This
indicates that such boundary conditions play a role in enforcing the
propagation of the constraints in the region interior to the boundary.
Additionally, we examine the related problem for a strongly hyperbolic
first-order reduction of the BSSN equations and determine the characteristic
fields that are prescribed by the three boundary conditions, as well as those
that are left arbitrary.Comment: 11 page
Cauchy-characteristic Evolution of Einstein-Klein-Gordon Systems
A Cauchy-characteristic initial value problem for the Einstein-Klein-Gordon
system with spherical symmetry is presented. Initial data are specified on the
union of a space-like and null hypersurface. The development of the data is
obtained with the combination of a constrained Cauchy evolution in the interior
domain and a characteristic evolution in the exterior, asymptotically flat
region. The matching interface between the space-like and characteristic
foliations is constructed by imposing continuity conditions on metric,
extrinsic curvature and scalar field variables, ensuring smoothness across the
matching surface. The accuracy of the method is established for all ranges of
, most notably, with a detailed comparison of invariant observables
against reference solutions obtained with a calibrated, global, null algorithm.Comment: Submitted to Phys. Rev. D, 16 pages, revtex, 7 figures available at
http://nr.astro.psu.edu:8080/preprints.htm
Invariant Manifolds, the Spatial Three-Body Problem and Space Mission Design
The invariant manifold structures of the collinear libration points for the
spatial restricted three-body problem provide the framework for understanding
complex dynamical phenomena from a geometric point of view.
In particular, the stable and unstable invariant manifold \tubes" associated
to libration point orbits are the phase space structures that provide a
conduit for orbits between primary bodies for separate three-body systems.
These invariant manifold tubes can be used to construct new spacecraft
trajectories, such as a \Petit Grand Tour" of the moons of Jupiter. Previous
work focused on the planar circular restricted three-body problem.
The current work extends the results to the spatial case
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