205 research outputs found
First-order framework and domain-wall/brane-cosmology correspondence
AbstractWe address the possibility of finding domain wall solutions from cosmological solutions in brane cosmology. We find first-order equations for corresponding cosmology/domain wall solutions induced on 3-branes. The quadratic term of energy density in the induced Friedmann equation plays a non-standard role and we discuss the way the standard cosmological and domain wall models are recovered as the brane tension becomes large and show how they can be described by four-dimensional supergravity action in such a limit. Finally, we show that gravity on the 3-brane is locally localized as one moves away from the two-dimensional domain walls living on the brane
3D black holes on a 2-brane in 4D Minkowski space
We investigate three-dimensional black hole solutions in the realm of pure
and new massive gravity in 2+1 dimensions induced on a 2-brane embedded in a
flat four-dimensional spacetime. There is no cosmological constant neither on
the brane nor on the four-dimensional bulk. Only gravitational fields are
turned on and we indeed find vacuum solutions as black holes in 2+1 dimensions
even in the absence of any cosmological solution. There is a crossover scale
that controls how far the three- or four-dimensional gravity manifests on the
2-brane. Our solutions also indicate that local BTZ and SdS_3 solutions can
flow to local four-dimensional Schwarzschild like black holes, as one probes
from small to large distances, which is clearly a higher dimensional
manifestation on the 2-brane. This is similar to the DGP scenario where the
effects of extra dimensions for large probed distances along the brane
manifest.Comment: 10 pages, 5 figures, to appear in PL
Higher Derivative Corrections to Eleven Dimensional Supergravity via Local Supersymmetry
In this paper we derive higher derivative corrections to the eleven
dimensional supergravity by applying the Noether method with respect to the N=1
local supersymmetry. An ansatz for the higher derivative effective action,
which includes quartic terms of the Riemann tensor, is parametrized by 132
parameters. Then we show that by the requirement of the local supersymmetry,
the higher derivative effective action is essentially described by two
parameters. The bosonic parts of these two superinvariants completely match
with the known results obtained by the perturbative calculations in the type
IIA superstring theory. Since the calculations are long and systematic, we
build the computer programming to check the cancellation of the variations
under the local supersymmetry. This is an extended version of our previous
paper hep-th/0508204.Comment: 67 pages, no figure, references added, typos correcte
String and M-theory Deformations of Manifolds with Special Holonomy
The R^4-type corrections to ten and eleven dimensional supergravity required
by string and M-theory imply corrections to supersymmetric supergravity
compactifications on manifolds of special holonomy, which deform the metric
away from the original holonomy. Nevertheless, in many such cases, including
Calabi-Yau compactifications of string theory and G_2-compactifications of
M-theory, it has been shown that the deformation preserves supersymmetry
because of associated corrections to the supersymmetry transformation rules,
Here, we consider Spin(7) compactifications in string theory and M-theory, and
a class of non-compact SU(5) backgrounds in M-theory. Supersymmetry survives in
all these cases too, despite the fact that the original special holonomy is
perturbed into general holonomy in each case.Comment: Improved discussion of SU(5) holonomy backgrounds. Other minor typos
corrected. Latex with JHEP3.cls, 42 page
The ambiguity-free four-dimensional Lorentz-breaking Chern-Simons action
The four dimensional Lorentz-breaking finite and determined Chern-Simons like
action is generated as a one loop perturbative correction via an appropriate
Lorentz-breaking coupling of the gauge field with the spinor field. Unlike the
known schemes of calculations, within this scheme this term is found to be
regularization independent.Comment: Revtex4, 4 page
Lorentz-violating Chern-Simons action under high temperature in massless QED
Lorentz and CPT violating QED with massless fermions at finite temperature is
studied. We show that there is no ambiguity in the induced coefficient of the
Chern-Simons-like term that defines the so-called Carroll-Field-Jackiw model at
high temperature. We also show that this system constitutes an example where
the breaking of CPT and Lorentz symmetries is more severe at high temperature
than in the zero temperature case thus precluding any naive expectations of
Lorentz symmetry restoration.Comment: 6 pages, 1 figure, final version to appear in Phys. Lett.
Acoustic Black Holes from Abelian Higgs Model with Lorentz Symmetry Breaking
In this paper we derive acoustic black hole metrics in the (3+1) and
(2+1)-dimensional Abelian Higgs model with Lorentz symmetry breaking. In this
set up the sound waves lose the Lorentz boost invariance and suffer a
'birefringence' effect. We have found acoustic black holes and respective
Hawking temperatures depending on the Lorentz violating parameter. Furthermore,
we obtain an acoustic Kerr-like black hole metric with the Lorentz violating
term affecting its rate of loss of mass. We also have shown that for suitable
values of the Lorentz violating parameter a wider spectrum of particle wave
function can be scattered with increased amplitude by the acoustic black hole.Comment: 12 pages, Latex, no figures, version accepted to Phys. Lett.
Genetic diversity analysis of varronia curassavica Jacq. accessions using ISSR markers
Varronia curassavica Jacq. is a medicinal and aromatic plant from Brazil with significant economic importance. Studies on genetic diversity in active germplasm banks (AGB) are essential for conservation and breeding programs. The aim of this study was to analyze the genetic diversity of V. curassavica accessions of the AGB of Medicinal and Aromatic Plants of the Federal University of Sergipe (UFS), using inter-simple sequence repeat molecular markers. Twenty-four primers were tested, and 14 were polymorphic and informative, resulting in 149 bands with 97.98% polymorphism. The UPGMA dendrogram divided the accessions into Clusters I and II. Jaccard similarity coefficients for pair-wise comparisons of accessions ranged between 0.24 and 0.78. The pairs of accessions VCUR-001/VCUR-503, VCUR-001/VCUR-504, and VCUR-104/VCUR-501 showed relatively low similarity (0.24), and the pair of accessions VCUR-402/VCUR403 showed medium similarity (0.78). Twenty-eight accessions were divided into three distinct clusters, according to the STRUCTURE analysis. The genetic diversity of V. curassavica in the AGB of UFS is low to medium, and it requires expansion. Accession VCUR-802 is the most suitable for selection in breeding program of this species, since it clearly represents all of the diversity present in the AGB153CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTĂFICO E TECNOLĂGICO - CNPQCOORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL DE NĂVEL SUPERIOR - CAPESFINANCIADORA DE ESTUDOS E PROJETOS - FINEPFUNDAĂĂO DE APOIO Ă PESQUISA E Ă INOVAĂĂO TECNOLĂGICA DO ESTADO DE SERGIPE - FAPITECnĂŁo temnĂŁo temnĂŁo temnĂŁo te
Stationary solutions for the parity-even sector of the CPT-even and Lorentz-covariance-violating term of the standard model extension
In this work, we focus on some properties of the parity-even sector of the
CPT-even electrodynamics of the standard model extension. We analyze how the
six non-birefringent terms belonging to this sector modify the static and
stationary classical solutions of the usual Maxwell theory. We observe that the
parity-even terms do not couple the electric and magnetic sectors (at least in
the stationary regime). The Green's method is used to obtain solutions for the
field strengths E and B at first order in the Lorentz- covariance-violating
parameters. Explicit solutions are attained for point-like and spatially
extended sources, for which a dipolar expansion is achieved. Finally, it is
presented an Earth-based experiment that can lead (in principle) to an upper
bound on the anisotropic coefficients as stringent as
Comment: 8 pages, revtex style, revised published version, to appear in EPJC
(2009
Tachyons on Dp-branes from Abelian Higgs sphalerons
We consider the Abelian Higgs model in a (p+2)-dimensional space time with
topology M^{p+1} x S^1 as a field theoretical toy model for tachyon
condensation on Dp-branes. The theory has periodic sphaleron solutions with the
normal mode equations resembling Lame-type equations. These equations are
quasi-exactly solvable (QES) for specific choices of the Higgs- to gauge boson
mass ratio and hence a finite number of algebraic normal modes can be computed
explicitely. We calculate the tachyon potential for two different values of the
Higgs- to gauge boson mass ratio and show that in comparison to previously
studied pure scalar field models an exact cancellation between the negative
energy contribution at the minimum of the tachyon potential and the brane
tension is possible for the simplest truncation in the expansion about the
field around the sphaleron. This gives further evidence for the correctness of
Sen's conjecture.Comment: 14 Latex pages including 3 eps-figure
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