The primordial explosion of a false white hole from a 5D vacuum

We explore the cosmological consequences of some possible big bang produced by a black-hole with mass $M$ in an 5D extended SdS. Under these particular circumstances, the effective 4D metric obtained by the use of a constant foliation on the extra coordinate is comported as a false white-hole (FWH), which evaporates for all unstable modes that have wavelengths bigger than the size of the FWH. Outside the white hole the repulsive gravitational field can be considered as weak, so that the dynamics for fluctuations of the inflaton field and the scalar perturbations of the metric can be linearized.Comment: Final version to be published in PLB. arXiv admin note: substantial text overlap with arXiv:1304.698

Gravitational waves from a Weyl-Integrable manifold: a new formalism

We study the variational principle over an Hilbert-Einstein like action for an extended geometry taking into account torsion and non-metricity. By extending the semi-Riemannian geometry, we obtain an effective energy-momentum tensor which can be interpreted as physical sources. As an application we develop a new manner to obtain the gravitational wave equations on a Weyl-integrable manifold taking into account the non-metricity and non-trivial boundary conditions on the minimization of the action, which can be identified as possible sources for the cosmological constant and provides two different equations for gravitational waves. We examine gravitational waves in a pre-inflationary cosmological model.Comment: Accepted in Physics of the Dark Univers

Present accelerated expansion of the universe from new Weyl-Integrable gravity approach

We investigate if a recently introduced formulation of general relativity on a Weyl-integrable geometry, contains cosmological solutions exhibiting acceleration in the present cosmic expansion. We derive the general conditions to have acceleration in the expansion of the universe and obtain a particular solution for the Weyl scalar field describing a cosmological model for the present time in concordance with the data combination Planck + WP + BAO + SN.Comment: Version to be published in Eur. Phys. J.

Gauge invariant fluctuations of the metric during inflation from new scalar-tensor Weyl-Integrable gravity model

We investigate gauge invariant scalar fluctuations of the metric during inflation in a non-perturbative formalism in the framework of a recently introduced scalar-tensor theory of gravity formulated on a Weyl-Integrable geometry. We found that the Weyl scalar field can play the role of the inflaton field in this theory. As an application we study the case of a power law inflation. In this case the quasi-scale invariance of the spectrum for scalar fluctuations of the metric is achieved for determined values of the $\omega$ parameter of the scalar-tensor theory. In our formalism the physical inflaton field has a geometrical origin.Comment: 9 pages, no figures. This is a revised version accepted for publication in Physical Review

Scalar fluctuations of the scalar metric during inflation from a non-perturbative 5D large-scale repulsive gravity model

We develop a non-perturbative formalism for scalar metric fluctuations from a 5D extended version of general relativity in vacuum. In this work we concentrate our efforts on calculations valid on large cosmological scales, which are the dominant during the inflationary phase of the universe. The resulting metric in this limit is obtained after implementing a planar coordinate transformation on a 5D Ricci-flat metric solution. We calculate the spectrum of these fluctuations with an effective 4D Schwarzschild-de Sitter spacetime on cosmological scales, which is obtained after we make a static foliation on the non-compact extra coordinate. Our results show how the squared metric fluctuations of the primordial universe become scale invariant with the inflationary expansion.Comment: Final version to be published in EPJ

Gravitoelectromagnetic inflation and seeds of cosmic magnetic fields from geometrical Weyl-invariant scalar-tensor theory of gravity

We investigate cosmological inflationary scenarios from a gravitoelectromagnetic theory. Our work is formulated in the light of a recently introduced geometrical Weyl-Invariant scalar-tensor theory of gravity, where the nature of both the electromagnetic potential and the inflaton field is attributed to the space-time geometry. We obtain a Harrison-Zeldovich power spectrum for quantum fluctuations of the inflaton field. In our model the electromagnetic fields have also a nearly scale invariant power spectrum for a power-law inflation. We found that the the seed magnetic fields have a nearly scale invariant power spectrum and generate in the present times cosmic magnetic fields of the order $\lesssim 10^{9}$ gauss, in good agreement with CMB observations.Comment: 11 pages, 1 figur

Noncompact KK theory of gravity: stochastic treatment for a nonperturbative inflaton field in a de Sitter expansion

We study a stochastic formalism for a nonperturbative treatment of the inflaton field in the framework of a noncompact Kaluza-Klein (KK) theory during an inflationary (de Sitter) expansion, without the slow-roll approximation.Comment: version to be published in Phys. Lett.

Passing to an effective 4D phantom cosmology from 5D vacuum theory of gravity

Starting from a five-dimensional (5D) vacuum theory of gravity where the extra coordinate is considered as noncompact, we investigate the possibility of inducing four-dimensional (4D) phantom scenarios by applying form-invariance symmetry transformations. In particular we obtain phantom scenarios for two cosmological frameworks. In the first framework we deal with an induced 4D de-Sitter expansion and in the second one a 4D induced model where the expansion of the universe is dominated by a decreasing cosmological parameter $\Lambda(t)$ is discussed.Comment: version accepted in Physics Letters