217 research outputs found
Brane-world cosmology
A simple model of the brane-world cosmology has been proposed, which is
characterized by four parameters, the bulk cosmological constant, the spatial
curvature of the universe, the radiation strength arising from bulk space-time
and the breaking parameter of -symmetry. The bulk space-time is assumed to
be locally static five-dimensional analogue of the Schwarzschild-anti-de Sitter
space-time, and then the location of three-brane is determined by metric
junction. The resulting Friedmann equation recovers standard cosmology, and a
new term arises if the assumption -symmetry is dropped, which behaves as
cosmological term in the early universe, next turns to negative curvature term,
and finally damps rapidly.Comment: 4 pages, no figure
On the Topology of Black Lenses
The topological structure of the black holes in 5-dimensional space-times
with a horizon diffeomorphic with the lens space has been discussed. It has
been shown that such a black hole can emerge from the crease set, which is
composed of the plumbings of several 2-spheres, of the event horizon. It has
also been shown that such configurations are realized in the Kastor-Traschen
solution of the Einstein-Maxwell system.Comment: 27 pages, 19 figure
The gains from commitment when inflation persistence and data uncertainty coexist
This paper investigates how the gains from commitment are large when inflation persistence and data uncertainty coexist. We consider two types of data uncertainty: measurement errors of potential output and inflation. We show that under a situation where data uncertainty exists, there are large gains from commitment as long as inflation is not extremely forward-looking or backward-looking. In particular, an increase in measurement error of inflation reduces the gains from commitment when forward-looking inflation is important, whereas there are large gains from commitment as long as inflation is not extremely backward-looking.Inflation persistence, Data uncertainty, Optimal monetary policy
First-Quantized Theory of Expanding Universe from Field Quantization in Mini-Superspace
We propose an improved variant of the third-quantization scheme, for the
spatially homogeneous and isotropic cosmological models in Einstein gravity
coupled with a neutral massless scalar field. Our strategy is to specify a
semi-Riemannian structure on the mini-superspace and to consider the quantum
Klein-Gordon field on the mini-superspace. Then, the Hilbert space of this
quantum system becomes inseparable, which causes the creation of infinite
number of universes. To overcome this issue, we introduce a vector bundle
structure on the Hilbert space and the connection of the vector bundle. Then,
we can define a consistent unitary time evolution of the quantum universe in
terms of the connection field on the vector bundle. By doing this, we are able
to treat the quantum dynamics of a single-universe state. We also find an
appropriate observable set constituting the CCR-algebra, and obtain the
Schr\"odinger equation for the wave function of the single-universe state. We
show that the present quantum theory correctly reproduces the classical
solution to the Einstein equation.Comment: 21 pages, 1 figure, published versio
Black holes in three-dimensional Einstein-Born-Infeld-dilaton theory
The three-dimensional static and circularly symmetric solution of the
Einstein-Born-Infeld-dilaton system is derived. The solutions corresponding to
low energy string theory are investigated in detail, which include black hole
solutions if the cosmological constant is negative and the mass parameter
exceeds a certain critical value. Some differences between the Born-Infeld
nonlinear electrodynamics and the Maxwell electrodynamics are revealed.Comment: 10 pages LaTeX, 2 eps figures, accepted for publication in PR
Rotating Black Holes/Rings at Future Colliders
The hierarchy between the electroweak and Planck scales can be reduced when
the extra dimensions are compactified with large volume or with warped
geometry, resulting in the fundamental scale of the order of TeV. In such a
scenario, one can experimentally study the physics above the Planck scale. We
discuss black hole/ring production at future colliders.Comment: minor corrections in Appendix; irrelevant files delete
Rotating black holes at future colliders II: Anisotropic scalar field emission
This is the sequel to the first paper of the series, where we have discussed
the Hawking radiation from five-dimensional rotating black holes for spin 0,
1/2 and 1 brane fields in the low frequency regime. We consider the emission of
a brane localized scalar field from rotating black holes in general space-time
dimensions without relying on the low frequency expansions.Comment: 12 pages, 24 figure
Rotating black holes at future colliders: Greybody factors for brane fields
We study theoretical aspects of the rotating black hole production and
evaporation in the extra dimension scenarios with TeV scale gravity, within the
mass range in which the higher dimensional Kerr solution provides good
description. We evaluate the production cross section of black holes taking
their angular momenta into account. We find that it becomes larger than the
Schwarzschild radius squared, which is conventionally utilized in literature,
and our result nicely agrees with the recent numerical study by Yoshino and
Nambu within a few percent error for higher dimensional case. In the same
approximation to obtain the above result, we find that the production cross
section becomes larger for the black hole with larger angular momentum. Second,
we derive the generalized Teukolsky equation for spin 0, 1/2 and 1 brane fields
in the higher dimensional Kerr geometry and explicitly show that it is
separable in any dimensions. For five-dimensional (Randall-Sundrum) black hole,
we obtain analytic formulae for the greybody factors in low frequency expansion
and we present the power spectra of the Hawking radiation as well as their
angular dependence. Phenomenological implications of our result are briefly
sketched.Comment: Typo in basic equation corrected; Following calculations and results
unchange
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