Results 1  10
of
14
Cosmology of codimensiontwo braneworlds
 JHEP
, 2003
"... Abstract: We present a comprehensive study of the cosmological solutions of 6D braneworld models with azimuthal symmetry in the extra dimensions, moduli stabilization by flux or a bulk scalar field, and which contain at least one 3brane that could be identified with our world. We emphasize an unusu ..."
Abstract

Cited by 15 (2 self)
 Add to MetaCart
Abstract: We present a comprehensive study of the cosmological solutions of 6D braneworld models with azimuthal symmetry in the extra dimensions, moduli stabilization by flux or a bulk scalar field, and which contain at least one 3brane that could be identified with our world. We emphasize an unusual property of these models: their expansion rate depends on the 3brane tension either not at all, or in a nonstandard way, at odds with the naive expected dimensional reduction of these systems to 4D general relativity at low energies. Unlike other braneworld attempts to find a selftuning solution to the cosmological constant problem, the apparent failure of decoupling in these models is not associated with the presence of unstabilized moduli; rather it is due to automatic cancellation of the brane tension by the curvature induced by the brane. This provides some corroboration for the hope that these models provide a distinctive step toward understanding the smallness of the observed cosmological constant. However, we point out
Gradient formula for linearly selfinteracting branes
 Commun. Math. Phys
"... The computation of long range linear selfinteraction forces in string and higher dimensional brane models requires the evaluation of the gradients of regularised values of divergent selfinteraction potentials. It is shown that the appropriately regularised gradient in directions orthogonal to the ..."
Abstract

Cited by 7 (2 self)
 Add to MetaCart
(Show Context)
The computation of long range linear selfinteraction forces in string and higher dimensional brane models requires the evaluation of the gradients of regularised values of divergent selfinteraction potentials. It is shown that the appropriately regularised gradient in directions orthogonal to the brane surface will always be obtainable simply by multiplying the regularised potential components by just half the trace of the second fundamental tensor, except in the hypermembrane case for which the method fails. Whatever the dimension of the background this result is valid provided the codimension is two (the hyperstring case) or more, so it can be used for investigating braneworld scenarios with more than one extra space dimension. 1
Brane worlds: The gravity of escaping matter,” hepth/0003109
"... In the framework of a fivedimensional model with one 3brane and an infinite extra dimension, we discuss a process in which matter escapes from the brane and propagates into the bulk to arbitrarily large distances. An example is a decay of a particle of mass 2m residing on the brane into two partic ..."
Abstract

Cited by 4 (0 self)
 Add to MetaCart
(Show Context)
In the framework of a fivedimensional model with one 3brane and an infinite extra dimension, we discuss a process in which matter escapes from the brane and propagates into the bulk to arbitrarily large distances. An example is a decay of a particle of mass 2m residing on the brane into two particles of mass m that leave the brane and accelerate away. We calculate, in the linearized theory, the metric induced by these particles on the brane. This metric does not obey the fourdimensional Einstein equations and corresponds to a spherical gravity wave propagating along the fourdimensional future light cone. The fourdimensional spacetime left behind the spherical wave is flat, so the gravitational field induced in the brane world by matter escaping from the brane disappears in a causal way. 1 I. INTRODUCTION AND SUMMARY It has been found recently [1] that fourdimensional gravity may emerge as a low energy effective theory in models with noncompact extra dimensions (see also Refs [2,3]). One
and gravity in warped extradimensional models, in preparation
"... Warped extra dimension claims remarkable success: solving the hierarchy problem; explaining hierarchies in particle phenomenology; yielding standard cosmology, plus interesting nonstandard scenarios. Yet it has marked shortcomings: we overrely on a single toy model, RandallSundrum; we treat matter ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
(Show Context)
Warped extra dimension claims remarkable success: solving the hierarchy problem; explaining hierarchies in particle phenomenology; yielding standard cosmology, plus interesting nonstandard scenarios. Yet it has marked shortcomings: we overrely on a single toy model, RandallSundrum; we treat matter and gravity in an ad hoc, asymmetric way; and we conceptualize integrated 4D effective field theory inconsistently. I here construct sounder 4D effective field theories for matter and gravity in warped extra dimension — whether RandallSundrum or higher codimension. I track both Planck and particle scales through brane formation, beginning with fully extradimensional matter and gravity, at unified scale, in gravitationally warped backgrounds with bulk electroweak symmetrybreaking. This validates hierarchy solution, as warp generically drives 4D effective Planck and particle scales apart. It evades classic obstacles to warped confinement of matter: colocalizing particles and assuring effective charge universality. Diverse particles do fail to colocalize, generically and in discussed models; however, aggregate 4D effective field theory still holds, since hierarchy solution fixes unresolvably small extradimensional radius. Electromagnetic charge universality emerges generically, and weak charge universality in the RandallSundrum case.
MultiScale Physics from MultiBraneworlds
, 2002
"... This Thesis presents a study of higher dimensional braneworld models with nonfactorizable geometry. In the picture of braneworld, Standard Model fields are assumed to be localized or confined on a lower dimensional topological defect (brane) in the higher dimensional space (bulk). When the space i ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
This Thesis presents a study of higher dimensional braneworld models with nonfactorizable geometry. In the picture of braneworld, Standard Model fields are assumed to be localized or confined on a lower dimensional topological defect (brane) in the higher dimensional space (bulk). When the space is curved, due to the presence of an energy density distribution, the nontrivial geometry can induce localization of gravity across the extra dimension. This implies that, in particular constructions, gravity can be localized on the brane. The localization of gravity leads to the realization that, if extra dimensions exists, they need not be compact. It is shown that in the context of multibrane world constructions with localized gravity the phenomenon of multilocalization is possible. When the latter scenario is realized, the KK spectrum contains special ultralight and localized KK state(s). Existence of such states give the possibility that gravitational interactions as we realize them are the net effect of the massless graviton and the special KK state(s). Models that reproduce Newtonian gravity at intermediate distances even in the absence of massless graviton are also discussed. It shown that the massless limit of the propagator of massive graviton in curved spacetime (AdS or dS) is smooth in contrast to the case that
A cigarlike Universe
, 2003
"... Abstract: We study the localization of gravity on a stringlike topological defect within a 6dimensional spacetime. Assuming zero cosmological constant we find complete numerical solutions to a set of firstorder, Bogomol’nyiPrasadSommeferld (BPS)like, equations for the metric and the scalar fi ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
(Show Context)
Abstract: We study the localization of gravity on a stringlike topological defect within a 6dimensional spacetime. Assuming zero cosmological constant we find complete numerical solutions to a set of firstorder, Bogomol’nyiPrasadSommeferld (BPS)like, equations for the metric and the scalar field, where the dynamics of the latter are dictated by a supergravitytype potential. Our axially symmetric solutions have no deficit angle and factorize as AdS5 × S1 far from the core. They are regular everywhere, providing complete smooth cigarlike geometries. The total energy of these configurations depends only on the boundary conditions for the warp factor and it is shown to vanish.
hepth/0401085 Black Brane World from Gravitating Half σlump
, 2004
"... We study O(N +1) nonlinear σmodel in (p+1+N)dimensional curved spacetime with a negative cosmological constant, and find a new σlump solution with halfinteger winding and divergent energy. When the spatial structure of N extradimensions is determined by this global defect, a black σpbrane surr ..."
Abstract

Cited by 1 (1 self)
 Add to MetaCart
(Show Context)
We study O(N +1) nonlinear σmodel in (p+1+N)dimensional curved spacetime with a negative cosmological constant, and find a new σlump solution with halfinteger winding and divergent energy. When the spatial structure of N extradimensions is determined by this global defect, a black σpbrane surrounded by the degenerated horizon is formed and its nearhorizon geometry is identified as a warp geometry of a cigar type.
hepth/0401207 Scalar Hair of Global Defect and Black Brane World
, 2004
"... We consider a complex scalar field in (p + 3)dimensional bulk with a negative cosmological constant and study global vortices in two extradimensions. We reexamine carefully the coupled scalar and Einstein equations, and show that the boundary value of scalar amplitude at infinity of the extradime ..."
Abstract
 Add to MetaCart
(Show Context)
We consider a complex scalar field in (p + 3)dimensional bulk with a negative cosmological constant and study global vortices in two extradimensions. We reexamine carefully the coupled scalar and Einstein equations, and show that the boundary value of scalar amplitude at infinity of the extradimensions should be smaller than vacuum expectation value. The brane world has a cigarlike geometry with an exponentially decaying warp factor and a flat thick pbrane is embedded. Since a coordinate transformation identifies the obtained brane world as a black pbrane world bounded by a horizon, this strange boundary condition of the scalar amplitude is understood as existence of a short scalar hair.
THE INTERFACE OF COSMOLOGY WITH STRING AND MTHEORY
, 2000
"... The purpose of this review is to discuss recent developments occurring at the interface of cosmology with string and Mtheory. We begin with a short review of 1980s string cosmology and the BrandenbergerVafa mechanism for explaining spacetime dimensionality. It is shown how this scenario has been m ..."
Abstract
 Add to MetaCart
The purpose of this review is to discuss recent developments occurring at the interface of cosmology with string and Mtheory. We begin with a short review of 1980s string cosmology and the BrandenbergerVafa mechanism for explaining spacetime dimensionality. It is shown how this scenario has been modified to include the effects of pbrane gases in the early universe. We then introduce the PreBigBang scenario (PBB), HoˇravaWitten heterotic Mtheory and the work of Lukas, Ovrut and Waldram, and end with a discussion of large extra dimensions, the RandallSundrum model and Brane World cosmologies.
hepth/9912242 Metric Fluctuations in Brane Worlds
, 1999
"... Recently, a realization of the fourdimensional gravity on a brane in fivedimensional spacetime has been discussed. Randall and Sundrum have shown that the equation for the longitudinal components of the metric fluctuations admits a normalizable zero mode solution, which has been interpreted as the ..."
Abstract
 Add to MetaCart
Recently, a realization of the fourdimensional gravity on a brane in fivedimensional spacetime has been discussed. Randall and Sundrum have shown that the equation for the longitudinal components of the metric fluctuations admits a normalizable zero mode solution, which has been interpreted as the localized gravity on the brane. We find that equations, which include also the transverse components of the metric fluctuations, have a zeromode solution, which is not localized on the brane. This indicates that probably the effective theory is unstable or, in other words, actually it is not fourdimensional but fivedimensional. Perhaps a modification of the proposal by using matter fields can lead to the trapping of gravity to the brane.