72 research outputs found
Unparticle physics and lepton flavor violating radion decays in the Randall-Sundrum scenario
We predict the branching ratios of the lepton flavor violating radion decays
r -> e^{\pm} \mu^{\pm}, r -> e^{\pm} \tau^{\pm} and r ->\mu^{\pm} \tau^{\pm} in
the framework of the Randall-Sundrum scenario that the lepton flavor violation
is carried by the scalar unparticle mediation. We observe that their BRs are
strongly sensitive to the unparticle scaling dimension and, for its small
values, the branching ratios can reach to the values of the order of 10^{-8},
for the heavy lepton flavor case.Comment: 21 pages, 11 Figures, 1 Tabl
Expanding Cosmologies in Brane Geometries
Five dimensional gravity coupled, both in the bulk and on a brane, to a
scalar Liouville field yields a geometry confined to a strip around the brane
and with time dependent scale factors for the four geometry. In various limits
known models can be recovered as well as a temporally expanding four geometry
with a warp factor falling exponentially away from the brane. The effective
theory on the brane has a time dependent Planck mass and ``cosmological
constant''. Although the scale factor expands, the expansion is not an
acceleration.Comment: 7 pages, LaTex/RevTex
Self-gravitating domain walls and the thin-wall limit
We analyse the distributional thin wall limit of self gravitating scalar
field configurations representing thick domain wall geometries. We show that
thick wall solutions can be generated by appropiate scaling of the thin wall
ones, and obtain an exact solution for a domain wall that interpolates between
AdS_4 asymptotic vacua and has a well-defined thin wall limit.Solutions
representing scalar field configurations obtained via the same scaling but that
do not have a thin wall limit are also presented.Comment: 10 pages, revte
BPS Domain Wall Junctions in Infinitely Large Extra Dimensions
We consider models of scalar fields coupled to gravity which are
higher-dimensional generalizations of four dimensional supergravity. We use
these models to describe domain wall junctions in an anti-de Sitter background.
We derive Bogomolnyi equations for the scalar fields from which the walls are
constructed and for the metric. From these equations a BPS-like formula for the
junction energy can be derived. We demonstrate that such junctions localize
gravity in the presence of more than one uncompactified extra dimension.Comment: 17 pages, uses RevTeX, new references adde
Domain Walls of D=8 Gauged Supergravities and their D=11 Origin
Performing a Scherk-Schwarz dimensional reduction of D=11 supergravity on a
three-dimensional group manifold we construct five D=8 gauged maximal
supergravities whose gauge groups are the three-dimensional (non-)compact
subgroups of SL(3,R). These cases include the Salam-Sezgin SO(3) gauged
supergravity. We construct the most general half-supersymmetric domain wall
solutions to these five gauged supergravities. The generic form is a triple
domain wall solution whose truncations lead to double and single domain wall
solutions. We find that one of the single domain wall solutions has zero
potential but nonzero superpotential.
Upon uplifting to 11 dimensions each domain wall becomes a purely
gravitational 1/2 BPS solution. The corresponding metric has a 7+4 split with a
Minkowski 7-metric and a 4-metric that corresponds to a gravitational
instanton. These instantons generalize the SO(3) metric of Belinsky, Gibbons,
Page and Pope (which includes the Eguchi-Hanson metric) to the other Bianchi
types of class A.Comment: 23 pages, 1 figure, minor changes, references adde
Massless Localized Vector Field on a Wall in D=5 SQED with Tensor Multiplets
Massless localized vector field is obtained in five-dimensional
supersymmetric (SUSY) QED coupled to tensor multiplets as a half BPS solution.
The four-dimensional gauge coupling is obtained as a topological charge. We
also find all the (bosonic) massive modes exactly for a particular value of a
parameter, demonstrating explicitly the existence of a mass gap. The
four-dimensional Coulomb law is shown to hold for sources placed on the wall.Comment: 18 pages, 3 figures, First version is completely replaced due to an
error of submitting a different pape
Bulk inflaton shadows of vacuum gravity
We introduce a -dimensional vacuum description of five-dimensional
bulk inflaton models with exponential potentials that makes analysis of
cosmological perturbations simple and transparent. We show that various
solutions, including the power-law inflation model recently discovered by
Koyama and Takahashi, are generated from known -dimensional vacuum
solutions of pure gravity. We derive master equations for all types of
perturbations, and each of them becomes a second order differential equation
for one master variable supplemented by simple boundary conditions on the
brane. One exception is the case for massive modes of scalar perturbations. In
this case, there are two independent degrees of freedom, and in general it is
difficult to disentangle them into two separate sectors.Comment: 22 pages, 4 figures, revtex; v2: references adde
Stability of Compactifications
We examine the stability of . The initial data constructed by De Wolfe et al \cite{Gary} has been
carefully analyised and we have confirmed that there is no lower bound for the
total mass for . The effective action on has been derived
for dilatonic compactification of the system to describe the non-linear
fluctuation of the background space-time. The stability is discussed applying
the positive energy theorem to the effective theory on AdS, which again shows
the stability for .Comment: 6 pages, 3 figure
New Supersymmetric String Compactifications
We describe a new class of supersymmetric string compactifications to 4d
Minkowski space. These solutions involve type II strings propagating on
(orientifolds of) non Calabi-Yau spaces in the presence of background NS and RR
fluxes. The simplest examples have descriptions as cosets, generalizing the
three-dimensional nilmanifold. They can also be thought of as twisted tori. We
derive a formula for the (super)potential governing the light fields, which is
generated by the fluxes and certain ``twists'' in the geometry. Detailed
consideration of an example also gives strong evidence that in some cases,
these exotic geometries are related by smooth transitions to standard
Calabi-Yau or G2 compactifications of M-theory.Comment: 43 pages, harvmac bi
Solvable Models of Domain Walls in N=1 Supergravity
A class of exactly solvable models of domain walls are worked out in D=4
supergravity. We develop a method to embed globally supersymmetric
theories with exact BPS domain wall solutions into supergravity, by introducing
a gravitationally deformed superpotential. The gravitational deformation is
natural in the spirit of maintaining the K\"ahler invariance. The solutions of
the warp factor and the Killing spinor are also obtained. We find that three
distinct behaviors of warp factors arise depending on the value of a constant
term in the superpotential : exponentially decreasing in both sides of the
wall, flat in one side and decreasing in the other, and increasing in one side
and decreasing in the other. Only the first possibility gives the localized
massless graviton zero mode. Models with multi-walls and models with runaway
vacua are also discussed.Comment: 10 pages, 3 figures; Misprints in three formulas are correcte
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