255 research outputs found
Vector field localization and negative tension branes
It is shown that negative tension branes in higher dimensions may lead to an
effective lower dimensional theory where the gauge-invariant vector fields
associated with the fluctuations of the metric are always massless and
localized on the brane. Explicit five-dimensional examples of this phenomenon
are provided. Furthermore, it is shown that higher dimensional gauge fields can
also be localized on these configurations with the zero mode separated from the
massive tower by a gap.Comment: 16 pages, LaTeX style; to appear in Phys. Rev.
The Randall-Sundrum Scenario with an Extra Warped Dimension
We investigate a scenario with two four-branes embedded in six dimensions.
When the metric is periodic and compact in one of the dimensions parallel to
the branes, the value of the effective cosmological constant for the remaining
five dimensions can assume a variety of values, determined by the dependence of
the metric on the sixth dimension. The picture that emerges resembles the
Randall-Sundrum model but with an extra warped dimension that allows the usual
brane-bulk fine tuning to be satisfied without finely tuning any of the
parameters in the underlying six dimensional theory. Although the action
contains terms with four derivatives of the metric, we show that when the
branes have a finite, natural thickness, such terms have only a small effect on
the Randall-Sundrum structure. The presence of these four derivative terms also
allows a configuration that resembles that produced by a domain wall but which
results from gravity alone.Comment: 12 pages, 3 figures, requires harvmac and picte
Dimensional Reduction of the 5D Kaluza-Klein Geodesic Deviation Equation
In the work of Kerner et al. (2001) the problem of the geodesic deviation in
a 5D Kaluza Klein background is faced. The 4D space-time projection of the
resulting equation coincides with the usual geodesic deviation equation in the
presence of the Lorenz force, provided that the fifth component of the
deviation vector satisfies an extra constraint which takes into account the
conservation along the path. The analysis was performed setting as a
constant the scalar field which appears in Kaluza-Klein model. Here we focus on
the extension of such a work to the model where the presence of the scalar
field is considered. Our result coincides with that of Kerner et al. when the
minimal case is considered, while it shows some departures in the
general case. The novelty due to the presence of is that the variation
of the between the two geodesic lines is not conserved during the motion;
an exact law for such a behaviour has been derived.Comment: 9 page
Thick brane in 7D and 8D spacetimes
We consider a thick brane model supported by two interacting scalar fields in
7D and 8D general relativity. Using the special type of a potential energy, we
obtain numerically the regular asymptotically flat vacuum solutions. A
possibility of obtaining the similar solutions for an arbitrary number of the
extra spatial dimensions is estimated.Comment: 3 Ref's are adde
A Note on Solitons in Brane Worlds
We obtain the zero mode effective action for gravitating objects in the bulk
of dilatonic domain walls. Without additional fields included in the bulk
action, the zero mode effective action reproduces the action in one lower
dimensions obtained through the ordinary Kaluza-Klein (KK) compactification,
only when the transverse (to the domain wall) component of the bulk metric does
not have non-trivial term depending on the domain wall worldvolume coordinates.
With additional fields included in the bulk action, non-trivial dependence of
the transverse metric component on the domain wall worldvolume coordinates
appears to be essential in reproducing the lower-dimensional action obtained
via the ordinary KK compactification. We find, in particular, that the
effective action for the charged (p+1)-brane in the domain wall bulk reproduces
the action for the p-brane in one lower dimensions.Comment: 13 pages, LaTe
Gauge-invariant fluctuations of scalar branes
A generalization of the Bardeen formalism to the case of warped geometries is
presented. The system determining the gauge-invariant fluctuations of the
metric induced by the scalar fluctuations of the brane is reduced to a set of
Schr\"odinger-like equations for the Bardeen potentials and for the canonical
normal modes of the scalar-tensor action. Scalar, vector and tensor modes of
the geometry are classified according to four-dimensional Lorentz
transformations. While the tensor modes of the geometry live on the brane
determining the corrections to Newton law, the scalar and and vector
fluctuations exhibit non normalizable zero modes and are, consequently, not
localized on the brane. The spectrum of the massive modes of the fluctuations
is analyzed using supersymmetric quantum mechanics.Comment: 29 pages in Latex styl
Non- symmetric braneworlds in scalar tensorial gravity
We obtain, via the Gauss-Codazzi formalism, the expression of the effective
Einstein-Brans-Dicke projected equations in a non- symmetric
braneworld scenario which presents hybrid compactification. It is shown that
the functional form of such equations resembles the one in the Einstein's case,
except by the fact that they bring extra informations in the context of exotic
compactifications.Comment: 12 pages, LATEX file, no figures. Accepted for publication in the
European Physical Journal
Power-Law Inflation from the Rolling Tachyon
Modeling the potential by an inverse square law in terms of the tachyon field
() we find exact solution for spatially flat isotropic
universe.We show that for the model undergoes power-law
inflation. A way to construct other exact solutions is specified and
exemplified.Comment: References added. Matches the version in print. To appear in PR
The Collapse of Large Extra Dimensions
In models of spacetime that are the product of a four-dimensional spacetime
with an ``extra'' dimension, there is the possibility that the extra dimension
will collapse to zero size, forming a singularity. We ask whether this collapse
is likely to destroy the spacetime. We argue, by an appeal to the
four-dimensional cosmic censorship conjecture, that--at least in the case when
the extra dimension is homogeneous--such a collapse will lead to a singularity
hidden within a black string. We also construct explicit initial data for a
spacetime in which such a collapse is guaranteed to occur and show how the
formation of a naked singularity is likely avoided.Comment: Uses revtex
5-dimensional Quantum Gravity Effects in Exclusive Double Diffractive Events
The experimentally measurable effects related to extra dimensional gravity in
a RS-type brane world are estimated. Two options of the RS framework (namely,
with small and large curvature) are considered. It is shown that both can be
detected by the joint experiment of the CMS and TOTEM Collaborations at the
LHC.Comment: 11 pages, 6 figures, 4 tables, acknowledgments are adde
- …