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Mauricio Bellini

Publications and source records attributed to Mauricio Bellini.

At least 91 records · Page 5Linked to original sources
arXiv2009

Extended General Relativity: large-scale antigravity and short-scale gravity with ω=-1 from five dimensional vacuum

Considering a five-dimensional (5D) Riemannian spacetime with a particular stationary Ricci-flat metric, we obtain in the framework of the induced matter theory an effective 4D static and spherically symmetric metric which give us ordinary gravitatory solutions on small (planetary and astrophysical) scales, but repulsive (antigravity) forces on very large (cosmological) scales with ω= -1. Our approach is an unified manner to describe dark energy, dark matter and ordinary matter. We illustrate the theory with two examples, the solar system and the great attractor. From the geometrical point of view, these results follow from the assumption that exists a confining force that make possible that test particles move on a given 4D hypersurface.

gr-qc↗
arXiv2009

Primordial large-scale electromagnetic fields from Gravitoelectromagnetic Inflation

We investigate the origin and evolution of primordial electric and magnetic fields in the early universe, when the expansion is governed by a cosmological constant $Λ_0$. Using the gravitoelectromagnetic inflationary formalism with $A_0=0$, we obtain the power of spectrums for large-scale magnetic fields and the inflaton field fluctuations during inflation. A very important fact is that our formalism is {\em naturally non-conformally invariant}.

gr-qc↗
arXiv2009

The seed of magnetic monopoles in the early inflationary universe from a 5D vacuum state

Starting from a 5D Riemann flat metric, we have induced an effective 4D Hermitian metric which has an antisymmetric part which is purely imaginary. We have worked an example in which both, non-metricity and contorsion are zero. We obtained that the production of monopoles should be insignificant at the end of inflation and the tensor metric should come asymptotically diagonal and describing a nearly 4D de Sitter expansion.

gr-qc↗
arXiv2009

A confirmation of agreement of different approaches for scalar gauge-invariant metric perturbations during inflation

We revisit an extension of the well-known formalism for gauge-invariant scalar metric fluctuations, to study the spectrums for both, the inflaton and gauge invariant (scalar) metric fluctuations in the framework of a single field inflationary model where the quasi-exponential expansion is driven by an inflation which is minimally coupled to gravity. The proposal here examined is valid also for fluctuations with large amplitude, but for cosmological scales, where vector and tensor perturbations can be neglected and the fluid is irrotacional.

gr-qc↗
arXiv2008

Dark energy from gravitoelectromagnetic inflation?

Gravitoectromagnetic Inflation (GI) was introduced to describe in an unified manner, electromagnetic, gravitatory and inflaton fields from a 5D vacuum state. On the other hand, the primordial origin and evolution of dark energy is today unknown. In this letter we show using GI that the zero modes of some redefined vector fields $B_i=A_i/a$ produced during inflation, could be the source of dark energy in the universe.

gr-qc↗
arXiv2008

Stochastic approach of gravitational waves in presence of a decaying cosmological parameter from a 5D vacuum theory of gravity

We develop an stochastic approach to study gravitational waves produced during the inflationary epoch under the presence of a decaying cosmological parameter, on a 5D geometrical background which is Riemann flat. We obtain that the squared tensor metric fluctuations depend strongly on the cosmological parameter $Λ(t)$ and we finally illustrate the formalism with an example of a decaying $Λ(t)$.

gr-qc↗
arXiv2008

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 $Λ(t)$ is discussed.

gr-qc↗
arXiv2007

Power spectrum of large-scale magnetic fields from Gravitoelectromagnetic inflation with a decaying cosmological parameter

Introducing a variable cosmological parameter $Λ(t)$ in a geometrical manner from a 5D Riemann-flat metric, we investigate the origin and evolution of primordial magnetic fields in the early universe, when the expansion is governed by a cosmological parameter $Λ(t)$ that decreases with time. Using the gravitoelectromagnetic inflationary formalism, but without the Feynman gauge, we obtain the power of spectrums for large-scale magnetic fields and the inflaton field fluctuations during inflation. A very important fact is that our formalism is {\em naturally non-conformally invariant}.

hep-th↗
arXiv2007

Metric fluctuations from a NKK theory of gravity in a de Sitter expansion

A gauge invariant metric fluctuations formalism from a non-compact Kaluza-Klein (NKK) theory of gravity is presented in this talk notes. In this analysis we recover the well-known result $\frac{delta ρ}ρ\simeq 2Φ$ obtained typically in the standard 4D semiclassical approach to inflation and also the spectrum of this fluctuations becomes dependent of the fifth (space-like) coordinate. This fact allows to establish an interval of values for the wave number associated with the fifth dimension.

gr-qc↗
arXiv2007

Quintessential inflation from a variable cosmological constant in a 5D vacuum

We explore an effective 4D cosmological model for the universe where the variable cosmological constant governs its evolution and the pressure remains negative along all the expansion. This model is introduced from a 5D vacuum state where the (space-like) extra coordinate is considered as noncompact. The expansion is produced by the inflaton field, which is considered as nonminimally coupled to gravity. We conclude from experiental data that the coupling of the inflaton with gravity should be weak, but variable in different epochs of the evolution of the universe.

gr-qc↗
arXiv2007

Stochastic gravitoelectromagnetic inflation

Gravitoelectromagnetic inflation was recently introduced to describe, in an unified manner, electromagnetic, gravitatory and inflaton fields in the early (accelerated) inflationary universe from a 5D vacuum state. In this paper, we study a stochastic treatment for the gravitoelectromagnetic components $A_B=(A_μ,ϕ)$, on cosmological scales. We focus our study on the seed magnetic fields on super Hubble scales, which could play an important role in large scale structure formation of the universe.

gr-qc↗