129 research outputs found
Signature of Randall-Sundrum Quantum Gravity model in scattering in the TeV range
We examine the implications of the Randall-Sundrum gravity models on
scattering in the TeV range.Comment: 7 pages, 4 figure
Neutrino lensing and modification of Newtonian gravity at large distances
The nature of the modification to neutrino lensing from galaxies, as caused
by possible modifications to Newtonian gravity at large distances, is studied.Comment: 6 pages, 1 figur
Shifts in the Properties of the Higgs Boson from Radion Mixing
We examine how mixing between the Standard Model Higgs boson, , and the
radion present in the Randall-Sundrum model of localized gravity modifies the
expected properties of the Higgs boson. In particular, we demonstrate that the
total and partial decay widths of the Higgs, as well as the branching
fraction, can be substantially altered from their Standard Model expectations.
The remaining branching fractions are modified less than \lsim 5% for most of
the parameter space volume.Comment: 17 pages, 7 figs., LaTex; revised versio
Unruh Radiation, Holography and Boundary Cosmology
A uniformly acclerated observer in anti-deSitter space-time is known to
detect thermal radiation when the acceleration exceeds a critical value. We
investigate the holographic interpretation of this phenomenon. For uniformly
accelerated trajectories transverse to the boundary of the AdS space, the
hologram is a blob which expands along the boundary. Observers on the boundary
co-moving with the hologram become observers in cosmological space-times. For
supercritical accelerations one gets a Milne universe when the holographic
screen is the boundary in Poincare coordinates, while for the boundary in
hyperspherical coordinates one gets deSitter spacetimes. The presence or
absence of thermality is then interpreted in terms of specific classes of
observers in these cosmologies.Comment: LaTeX, 35 pages, 3 figures. A reference is added and typos are
correcte
Lensing at cosmological scales: a test of higher dimensional gravity
Recent developments in gravitational lensing astronomy have paved the way to
genuine mappings of the gravitational potential at cosmological scales. We
stress that comparing these data with traditional large scale structure surveys
will provide us with a test of gravity at such scales. These constraints could
be of great importance in the framework of higher dimensional cosmological
models.Comment: 4 pages, latex, 3 figure
Influence of a Brane Tension on Phantom and Massive Scalar Field Emission
We elaborate the signature of the extra dimensions and brane tension in the
process of phantom and massive scalar emission in the spacetime of
(4+n)-dimensional tense brane black hole. Absorption cross section, luminosity
of Hawking radiation and cross section in the low-energy approximation were
found. We envisage that parameter connected with the existence of a brane
imprints its role in the Hawking radiation of the considered fields.Comment: 7 pages, * figures, RevTex, to be published in General Relativity and
Gravitatio
String Theoretic Bounds on Lorentz-Violating Warped Compactification
We consider warped compactifications that solve the 10 dimensional
supergravity equations of motion at a point, stabilize the position of a
D3-brane world, and admit a warp factor that violates Lorentz invariance along
the brane. This gives a string embedding of ``asymmetrically warped'' models
which we use to calculate stringy (\alpha') corrections to standard model
dispersion relations, paying attention to the maximum speeds for different
particles. We find, from the dispersion relations, limits on gravitational
Lorentz violation in these models, improving on current limits on the speed of
graviton propagation, including those derived from field theoretic loops. We
comment on the viability of models that use asymmetric warping for self-tuning
of the brane cosmological constant.Comment: 20pg, JHEP3; v2 additional references, slight change to intro; v3.
added referenc
Quantized bulk fermions in the Randall-Sundrum brane model
The lowest order quantum corrections to the effective action arising from
quantized massive fermion fields in the Randall-Sundrum background spacetime
are computed. The boundary conditions and their relation with gauge invariance
are examined in detail. The possibility of Wilson loop symmetry breaking in
brane models is also analysed. The self-consistency requirements, previously
considered in the case of a quantized bulk scalar field, are extended to
include the contribution from massive fermions. It is shown that in this case
it is possible to stabilize the radius of the extra dimensions but it is not
possible to simultaneously solve the hierarchy problem, unless the brane
tensions are dramatically fine tuned, supporting previous claims.Comment: 25 pages, 1 figure, RevTe
D-Sitter Space: Causal Structure, Thermodynamics, and Entropy
We study the entropy of concrete de Sitter flux compactifications and
deformations of them containing D-brane domain walls. We determine the relevant
causal and thermodynamic properties of these "D-Sitter" deformations of de
Sitter spacetimes. We find a string scale correspondence point at which the
entropy localized on the D-branes (and measured by probes sent from an observer
in the middle of the bubble) scales the same with large flux quantum numbers as
the entropy of the original de Sitter space, and at which Bousso's bound is
saturated by the D-brane degrees of freedom (up to order one coefficients) for
an infinite range of times. From the geometry of a static patch of D-Sitter
space and from basic relations in flux compactifications, we find support for
the possibility of a low energy open string description of the static patch of
de Sitter space.Comment: 46 pages, harvmac big; 14 figure
Q ball inflation
We show that inflation can occur in the core of a Q-ball.Comment: 11 pages, latex2e, no figure, references added, final version to
appear in PR
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