310 research outputs found
Fractal extra dimension in Kaluza-Klein theory
Kaluza-Klein theory in which the geometry of an additional dimension is
fractal has been considered. In such a theory the mass of an elementary
electric charge appears to be many orders of magnitude smaller than the Planck
mass, and the "tower" of masses which correspond to higher integer charges
becomes aperiodic.Comment: 3 pages, accepted for publication in Phys.Rev.D (submitted on
3.28.2001
Hodge Duality on the Brane
It has been claimed that whereas scalars can be bound to a Randall-Sundrum
brane, higher p-form potentials cannot, in contradiction with the Hodge duality
between 0-form and 3-form potentials in the five-dimensional bulk. Here we show
that a 3-form in the bulk correctly yields a 2-form on the brane, in complete
agreement with both bulk and brane duality. We also emphasize that the
phenomenon of photon screening in the Randall-Sundrum geometry is ruled out by
the bulk Einstein equation.Comment: 6 pages, Latex. We emphasize that the phenomenon of photon screening
in the Randall-Sundrum geometry is ruled out by the bulk Einstein equatio
Localization of Bulk Form Fields on Dilatonic Domain Walls
We study the localization properties of bulk form potentials on dilatonic
domain walls. We find that bulk form potentials of any ranks can be localized
as form potentials of the same ranks or one lower ranks, for any values of the
dilaton coupling parameter. For large enough values of the dilaton coupling
parameter, bulk form potentials of any ranks can be localized as form
potentials of both the same ranks and one lower ranks.Comment: 9 pages, LaTeX, reference adde
Path integral formulation of Hodge duality on the brane
In the warped compactification with a single Randall-Sundrum brane, a
puzzling claim has been made that scalar fields can be bound to the brane but
their Hodge dual higher-rank anti-symmetric tensors cannot. By explicitly
requiring the Hodge duality, a prescription to resolve this puzzle was recently
proposed by Duff and Liu. In this note, we implement the Hodge duality via path
integral formulation in the presence of the background gravity fields of warped
compactifications. It is shown that the prescription of Duff and Liu can be
naturally understood within this framework.Comment: 7 pages, LaTe
Complementarity of the Maldacena and Karch-Randall Pictures
We perform a one-loop test of the holographic interpretation of the
Karch-Randall model, whereby a massive graviton appears on an AdS_4 brane in an
AdS_5 bulk. Within the AdS/CFT framework, we examine the quantum corrections to
the graviton propagator on the brane, and demonstrate that they induce a
graviton mass in exact agreement with the Karch-Randall result. Interestingly
enough, at one loop order, the spin 0, spin 1/2 and spin 1 loops contribute to
the dynamically generated (mass)^2 in the same 1: 3: 12 ratio as enters the
Weyl anomaly and the 1/r^3 corrections to the Newtonian gravitational
potential.Comment: 20 pages, Revtex 3, Discussion on the absence of a scalar ghost
clarified; Additional details on the computation give
Vanishing of cosmological constant in nonfactorizable geometry
We generalize the results of Randall and Sundrum to a wider class of
four-dimensional space-times including the four-dimensional Schwarzschild
background and de Sitter universe. We solve the equation for graviton
propagation in a general four dimensional background and find an explicit
solution for a zero mass bound state of the graviton. We find that this zero
mass bound state is normalizable only if the cosmological constant is strictly
zero, thereby providing a dynamical reason for the vanishing of cosmological
constant within the context of this model. We also show that the results of
Randall and Sundrum can be generalized without any modification to the
Schwarzschild background.Comment: 8 Pages(expanded version), Accepted in Phys. Rev.
Randall-Sundrum Brane Tensions
We show that the singular sources in the energy-momentum tensor for the
Randall-Sundrum brane world, viewed as a solution of type IIB supergravity, are
composed of two elements. One of these is a D3-brane source with tension
opposite in sign to the RS tension in five dimensions; the other arises from
patching two regions of flat ten-dimensional spacetime. This resolves an
apparent discrepancy between supersymmetry and the sign and magnitude of the RS
tension.Comment: Latex, 21 pages, 2 figure
Localization of supergravity on the brane
A supersymmetric Randall-Sundrum brane-world demands that not merely the
graviton but the entire supergravity multiplet be trapped on the brane. To
demonstrate this, we present a complete ansatz for the reduction of (D=5,N=4)
gauged supergravity to (D=4,N=2) ungauged supergravity in the Randall-Sundrum
geometry. We verify that it is consistent to lowest order in fermion terms. In
particular, we show how the graviphotons avoid the `no photons on the brane'
result because they do not originate from Maxwell's equations in D=5 but rather
from odd-dimensional self-duality equations. In the case of the fivebrane, the
Randall-Sundrum mechanism also provides a new Kaluza-Klein way of obtaining
chiral supergravity starting from non-chiral.Comment: 12 pages, Latex, minor improvements, references adde
Gauge/string duality and scalar glueball mass ratios
It has been shown by Polchinski and Strassler that the scaling of high energy
QCD scattering amplitudes can be obtained from string theory. They considered
an AdS slice as an approximation for the dual space of a confining gauge
theory. Here we use this approximation to estimate in a very simple way the
ratios of scalar glueball masses imposing Dirichlet boundary conditions on the
string dilaton field. These ratios are in good agreement with the results in
the literature. We also find that they do not depend on the size of the slice.Comment: 5 pages, no figures. References updated. Version published in JHE
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Objective Evaluation of the Somatogravic Illusion from Flight Data of an Airplane Accident
(1) Background: It is difficult for accident investigators to objectively determine whether spatial disorientation may have contributed to a fatal airplane accident. In this paper, we evaluate three methods to reconstruct the possible occurrence of the somatogravic illusion based on flight data recordings from an airplane accident. (2) Methods: The outputs of two vestibular models were compared with the âstandardâ method, which uses the unprocessed gravito-inertial acceleration (GIA). (3) Results: All three methods predicted that the changing orientation of the GIA would lead to a somatogravic illusion when no visual references were available. However, the methods were not able to explain the first pitch-down control input by the pilot flying, which may have been triggered by the inadvertent activation of the go-around mode and a corresponding pitch-up moment. Both vestibular models predicted a few seconds delay in the illusory tilt from GIA due to central processing and sensory integration. (4) Conclusions: While it is difficult to determine which method best predicted the somatogravic illusion perceived during the accident without data on the pilotâs pitch perception, both vestibular models go beyond the GIA analysis in taking into account validated vestibular dynamics, and they also account for other vestibular illusions. In that respect, accident investigators would benefit from a unified and validated vestibular model to better explain pilot actions in accidents related to spatial disorientation
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