169 research outputs found
Localization of Matter Fields in the 5D Standing Wave Braneworld
We investigate the localization problem of matter fields within the 5D
standing wave braneworld. In this model the brane emits anisotropic waves into
the bulk with different amplitudes along different spatial dimensions. We show
that in the case of increasing warp factor there exist the pure gravitational
localization of all kinds of quantum and classical particles on the brane. For
classical particles the anisotropy of the background metric is hidden, brane
fields exhibit standard Lorentz symmetry in spite of anisotropic nature of the
primordial 5D metric.Comment: The version accepted by JHE
Gravitational Localization of Matters in 6D
We present a new 3-brane solution to Einstein's equations in (1+5)-spacetime
with a negative bulk cosmological constant. This solution is a stringlike
defect solution with decreasing scale function approaching a finite non-zero
value in the radial infinity. It is shown that all local fields are localized
on the brane only through the gravitational interaction.Comment: 7 pages; added reference
Our World as an Expanding Shell
In the model where the Universe is considered as a thin shell expanding in
5-dimensional hyper-space there is a possibility to have just one scale for a
particle theory corresponding to the Universe thickness. From a realistic model
the relation of this parameter to the Universe size was found.Comment: RevTeX, 4 pages, no figure
Brane in 6D with increasing gravitational trapping potential
A new solution to Einstein equations in (1+5)-spacetime with an embedded
(1+3) brane is given. This solution localizes the zero modes of all kinds of
matter fields and 4-gravity on the (1+3) brane by an increasing, transverse
gravitational potential. This localization occurs despite the fact that the
gravitational potential is not a decreasing exponential, and asymptotically
approaches a finite value rather than zero.Comment: Revised paper. 6 pages, revtex 4. to be published in PR
Finsler Branes and Quantum Gravity Phenomenology with Lorentz Symmetry Violations
A consistent theory of quantum gravity (QG) at Planck scale almost sure
contains manifestations of Lorentz local symmetry violations (LV) which may be
detected at observable scales. This can be effectively described and classified
by models with nonlinear dispersions and related Finsler metrics and
fundamental geometric objects (nonlinear and linear connections) depending on
velocity/ momentum variables. We prove that the trapping brane mechanism
provides an accurate description of gravitational and matter field phenomena
with LV over a wide range of distance scales and recovering in a systematic way
the general relativity (GR) and local Lorentz symmetries. In contrast to the
models with extra spacetime dimensions, the Einstein-Finsler type gravity
theories are positively with nontrivial nonlinear connection structure,
nonholonomic constraints and torsion induced by generic off-diagonal
coefficients of metrics, and determined by fundamental QG and/or LV effects.Comment: latex2e, 11pt, 34 pages, the version accepted to Class. Quant. Gra
Anti-de-Sitter Island-Universes from 5D Standing Waves
We construct simple standing wave solutions in a 5D space-time with a ghost
scalar field. The nodes of these standing waves are 'islands' of 4D Minkowski
space-time. For the 5D model with increasing (decreasing) warp factor there are
a finite (infinite) number of nodes and thus Minkowski island-universes having
different parameters, such as gravitational and cosmological constants. This
feature is similar to the assumptions of the landscape models, which postulate
a large number of universes with different parameters. This standing wave
solution also provides a new localization mechanism - matter fields can reside
only on Minkowski 'islands', where the background space-time does not
oscillate.Comment: 14 page pre-print format. Discussion about connection to Weyl gravity
added and "E&M" localization method added. To be published MPL
Testing Relativity at High Energies Using Spaceborne Detectors
(ABRIDGED) The Gamma-ray Large Area Space Telescope (GLAST) will measure the
spectra of distant extragalactic sources of high energy gamma-rays. GLAST can
look for energy dependent propagation effects from such sources as a signal of
Lorentz invariance violation (LIV). Such sources should also exhibit high
energy spectral cutoffs from pair production interactions with low energy
photons. The properties of such cutoffs can also be used to test LIV. Detectors
to measure gamma-ray polarization can look for the depolarizing effect of
space-time birefingence predicted by loop quantum gravity. A spaceborne
detector array looking down on Earth to study extensive air showers produced by
ultrahigh energy cosmic rays can study their spectral properties and look for a
possible deviation from the predicted GZK effect as another signal of LIV.Comment: 14 pages, Text of invitated talk presented at the "From Quantum to
Cosmos: Fundamental Physics Studies from Space" meeting. More references
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Probing Brane-World Scenarios with Vacuum Refraction of Light Using Gamma-Ray Bursts
We argue that in fat brane-world scenarios the light propagating in vacuum will, because of massive ``Kaluza--Klein'' (KK) excitations, experience a refraction. The motion of a photon inside a fat brane can be decomposed in the longitudinal and transverse directions with respect to the surface of the brane. Since the light observable propagation is related only with the longitudinal motion, the obsered speed of light depends on the value of the momentum transverse fraction contributing as the massive KK excitations. This is directly connected with the energy of the particles emitting the light, and hence with the frequency of the light itself. Using recent results on the arrival times of radiation of different energies from the measurements of gamma-ray bursters with known redshifts, we establish the limit M>620 TeV on the inverse thickness of the brane, and thus on the masses of the KK excitations. This limit exceeds by at least one order of magnitude the typical energy scale currently in use to characterize brane phenomena in the realm of future colliders
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