834 research outputs found
Embedding the Reissner-Nordstrom spacetime in Euclidean and Minkowski spaces
We examine embedding diagrams of hypersurfaces in the Reissner-Nordstrom
black hole spacetime. These embedding diagrams serve as useful tools to
visualize the geometry of the hypersurfaces and of the whole spacetime in
general.Comment: 13 pages, 10 figure
The Contribution of the Cosmological Constant to the Relativistic Bending of Light Revisited
We study the effect of the cosmological constant on the bending of
light by a concentrated spherically symmetric mass. Contrarily to previous
claims, we show that when the Schwarzschild-de Sitter geometry is taken into
account, does indeed contribute to the bending.Comment: 5 pages, 2 figure
Static and dynamic traversable wormhole geometries satisfying the Ford-Roman constraints
It was shown by Ford and Roman in 1996 that quantum field theory severely
constrains wormhole geometries on a macroscopic scale. The first part of this
paper discusses a wide class of wormhole solutions that meet these constraints.
The type of shape function used is essentially generic. The constraints are
then discussed in conjunction with various redshift functions. Violations of
the weak energy condition and traversability criteria are also considered. The
second part of the paper analyzes analogous time-dependent (dynamic) wormholes
with the aid of differential forms. It is shown that a violation of the weak
energy condition is not likely to be avoidable even temporarily.Comment: 16 pages AMSTe
Axially symmetric rotating traversable wormholes
This paper generalizes the static and spherically symmetric traversable
wormhole geometry to a rotating axially symmetric one with a time-dependent
angular velocity by means of an exact solution. It was found that the violation
of the weak energy condition, although unavoidable, is considerably less severe
than in the static spherically symmetric case. The radial tidal constraint is
more easily met due to the rotation. Similar improvements are seen in one of
the lateral tidal constraints. The magnitude of the angular velocity may have
little effect on the weak energy condition violation for an axially symmetric
wormhole. For a spherically symmetric one, however, the violation becomes less
severe with increasing angular velocity. The time rate of change of the angular
velocity, on the other hand, was found to have no effect at all. Finally, the
angular velocity must depend only on the radial coordinate, confirming an
earlier result.Comment: 17 pages, AMSTe
Meson Mass Splittings in the Nonrelativistic Model
Mass splittings between isodoublet meson pairs and between and
mesons of the same valence quark content are computed in a detailed
nonrelativistic model. The field theoretic expressions for such splittings are
shown to reduce to kinematic and Breit-Fermi terms in the nonrelativistic
limit. Algebraic results thus obtained are applied to the specific case of the
linear-plus-Coulomb potential, with resultant numbers compared to experiment.Comment: 29 pages with 2 tables and 4 figures, LBL-32872 and UCB-PTH-92/3
Gravitational memory of natural wormholes
A traversable wormhole solution of general scalar-tensor field equations is
presented. We have shown, after a numerical analysis for the behavior of the
scalar field of Brans-Dicke theory, that the solution is completely
singularity--free. Furthermore, the analysis of more general scalar field
dependent coupling constants indicates that the gravitational memory phenomenon
may play an important role in the fate of natural wormholes.Comment: 14 pages revtex, 1 ps figur
Gauge Field Back-reaction on a Black Hole
The order fluctuations of gauge fields in the vicinity of a blackhole
can create a repulsive antigravity region extending out beyond the renormalized
Schwarzschild horizon. If the strength of this repulsive force increases as
higher orders in the back-reaction are included, the formation of a
wormhole-like object could occur.Comment: 17 pages, three figures available on request, in RevTe
Bohr-Sommerfeld quantization and meson spectroscopy
We use the Bohr-Sommerfeld quantization approach in the context of
constituent quark models. This method provides, for the Cornell potential,
analytical formulae for the energy spectra which closely approximate numerical
exact calculations performed with the Schrodinger or the spinless Salpeter
equations. The Bohr-Sommerfeld quantization procedure can also be used to
calculate other observables such as r.m.s. radius or wave function at the
origin. Asymptotic dependence of these observables on quantum numbers are also
obtained in the case of potentials which behave asymptotically as a power-law.
We discuss the constraints imposed by these formulae on the dynamics of the
quark-antiquark interaction.Comment: 13 page
Ground state energy in a wormhole space-time
The ground state energy of the massive scalar field with non-conformal
coupling on the short-throat flat-space wormhole background is calculated
by using zeta renormalization approach. We discuss the renormalization and
relevant heat kernel coefficients in detail. We show that the stable
configuration of wormholes can exist for . In particular case of
massive conformal scalar field with , the radius of throat of stable
wormhole . The self-consistent wormhole has radius of throat
and mass of scalar boson ( and
are the Planck length and mass, respectively).Comment: revtex, 18 pages, 3 eps figures. accepted in Phys.Rev.
Homogeneous singularities inside collapsing wormholes
We analyze analytically and numerically the origin of the singularity in the
course of the collapse of a wormhole with the exotic scalar field Psi with
negative energy density, and with this field Psi together with the ordered
magnetic field H. We do this under the simplifying assumptions of the spherical
symmetry and that in the vicinity of the singularity the solution of the
Einstein equations depends only on one coordinate (the homogeneous
approximation). In the framework of these assumptions we found the principal
difference between the case of the collapse of the ordinary scalar field Phi
with the positive energy density together with an ordered magnetic field H and
the collapse of the exotic scalar field Psi together with the magnetic field H.
The later case is important for the possible astrophysical manifestation of the
wormholes.Comment: 10 pages, 5 figures each of which has a),b),c),and d) sub-figures. To
be published in "Physical review. D, Particles, fields, gravitation, and
cosmology
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