2,390 research outputs found
The bang of a white hole in the early universe from a 6D vacuum state: Origin of astrophysical spectrum
Using a previously introduced model in which the expansion of the universe is
driven by a single scalar field subject to gravitational attraction induced by
a white hole during the expansion (from a 6D vacuum state), we study the origin
of squared inflaton fluctuations spectrum on astrophysical scales.Comment: Final version to be published in Eur. Phys. J.
Submanifolds in five-dimensional pseudo-Euclidean spaces and four-dimensional FRW universes
Equations for submanifolds, which correspond to embeddings of the
four-dimensional FRW universes in five-dimensional pseudo-Euclidean spaces, are
presented in convenient form in general case. Several specific examples are
considered.Comment: 7 pages, LaTeX, the mathematical part of this paper is based on the
withdrawn preprint arXiv:1012.0320 [gr-qc
Wesson's IMT with a Weylian bulk
The foundations of Wesson's induced matter theory are analyzed. It is shown
that the 5D empty bulk must be regarded rather as a Weylian space than as a
Riemannian one.The framework of a Weyl-Dirac version of Wesson's theory is
elaborated and discussed. The bulk possesses in addition to the metric tensor a
Weylian connection vector as well Dirac's gauge function; there are no sources
(mass, current) in the bulk. On the 4D brane one obtains a geometrically based
unified theory of gravitation and electromagnetism with mass, currents and
equations induced by the 5D bulkComment: 29 page
Stochastic emergence of inflaton fluctuations in a SdS primordial universe with large-scale repulsive gravity from a 5D vacuum
We develop a stochastic approach to study scalar field fluctuations of the
inflaton field in an early inflationary universe with a black-hole (BH), which
is described by an effective 4D SdS metric. Considering a 5D Ricci-flat SdS
static metric, we implement a planar coordinate transformation, in order to
obtain a 5D cosmological metric, from which the effective 4D SdS metric can be
induced on a 4D hypersurface. We found that at the end of inflation, the
squared fluctuations of the inflaton field are not exactly scale independent
and becomes sensitive with the mass of the BH.Comment: version accepted in European Physical Journal Plu
Erosion patterns in a sediment layer
We report here on a laboratory-scale experiment which reproduces a rich
variety of natural patterns with few control parameters. In particular, we
focus on intriguing rhomboid structures often found on sandy shores and flats.
We show that the standard views based on water surface waves come short to
explain the phenomenon and we evidence a new mechanism based on a mud avalanche
instability.Comment: 4 pages, 4 figures, to appear as Phys. Rev. E rapid com
Modular Invariance and Characteristic Numbers
We show that a general miraculous cancellation formula, the divisibility of
certain characteristic numbers and some other topologiclal results are con-
sequences of the modular invariance of elliptic operators on loop spaces.
Previously we have shown that modular invariance also implies the rigidity of
many elliptic operators on loop spaces.Comment: 14 page
Cost-efficient Deployment of Storage Unit in Residential Energy Systems
With the mushrooming of distributed renewable generation, energy storage unit (ESU) is becoming increasingly important in residential energy systems. This letter proposes a fractional programming model to determine the optimal power and energy capacities of residential ESUs, aiming at minimizing the ratio between the reduced electricity tariff and the investment cost of ESU, ensuring the minimal payback time. A decomposition algorithm is developed to solve the fractional program based on convex optimization; the subproblem is a dual convex quadratic program which provides cutting planes, and the master problem comes down to a small linear program after variable transformations. Compared to the widely used cost-minimum method, the proposed model is cost-efficient: it enjoys a higher rate of return which is usually welcomed by smaller consumers.© 2020 Institute of Electrical and Electronics Engineersfi=vertaisarvioimaton|en=nonPeerReviewed
An Embedding for General Relativity and its Implications for New Physics
We show that any solution of the 4D Einstein equations of general relativity
in vacuum with a cosmological constant may be embedded in a solution of the 5D
Ricci-flat equations with an effective 4D cosmological "constant" that is a
specific function of the extra coordinate. For unified theories of the forces
in higher dimensions, this has major physical implications
The influence of quintessence on the motion of a binary system in cosmology
We employ the metric of Schwarzschild space surrounded by quintessential
matter to study the trajectories of test masses on the motion of a binary
system. The results, which are obtained through the gradually approximate
approach, can be used to search for dark energy via the difference of the
azimuth angle of the pericenter. The classification of the motion is discussed.Comment: 7 pages, 1 figur
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