Mauricio Bellini

Single field inflationary models with non-compact Kaluza–Klein theory

Abstract We discuss a semiclassical treatment to inflationary models from Kaluza–Klein theory without the cylinder condition. We conclude that the evolution of the early universe could be described by a geodesic trajectory of a cosmological 5D metric here proposed, so that the effective 4D FRW background metric should be a hypersurface on a constant fifth dimension.

Inflationary cosmology from STM theory of gravity

I study the power-law and de Sitter expansions for the universe during inflation from the STM theory of gravity. In a de Sitter expansion the additional dimension is related to the cosmological constant Λ=3/ψ2. I find from experimental data that the mass of the inflaton field is m2=2/(3ψ2). The interesting in this case is that the inflaton field fluctuations are related to the fifth coordinate. In power-law expansion, the fifth coordinate (ψ) appears to be a dimensionless constant. Here, the ψ-value depends on the initial conditions. I find the 5D line element for this inflationary expansion, which is a function of the classical component of the inflaton. But the more important result here obtained is that in both cases there is not dynamical compactification during inflation.

Gravitoelectromagnetic inflation from a 5D vacuum state: A new formalism

We propose a novel formalism for inflation from a 5D vacuum state which could explain both, seeds of matter and magnetic fields in the early universe.

Noncompact Kaluza–Klein theory and inflationary cosmology: a complete formalism

Abstract A formalization of the recently introduced formalism for inflation is developed from a noncompact Kaluza–Klein theory. In particular, the case for a single scalar field inflationary model is studied. We obtain that the scalar potential, which assume different representations in different frames, has a geometrical origin.

Stochastic gravitoelectromagnetic inflation

Abstract 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 Letter, 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.

TOWARDS A THEORY OF WARM INFLATION OF THE UNIVERSE

The warm inflation scenario is an alternative mechanism which can explain the isotropic and homogeneous Universe in which we are living. In this work I extend a previously introduced formalism, without the restriction of the slow-roll regime. Quantum to classical transition of the fluctuations is studied by means of the `transition function here introduced. I found that the fluctuations of radiation energy density decrease with time and the thermal equilibrium at the end of inflation holds.

Inflaton field governed universe from NKK theory of gravity: Stochastic approach

Abstract.We study a non-perturbative single field (inflaton) governed cosmological model from a 5D non-compact Kaluza-Klein (NKK) theory of gravity. The inflaton field fluctuations are estimated for different epochs of the evolution of the universe. We conclude that the inflaton field has been sliding down its (quadratic) potential hill along the whole evolution of the universe and a mass is involved of the order of the Hubble parameter. In the model here developed the only free parameter is the Hubble parameter, which could be reconstructed in the future from Super Nova Acceleration Probe (SNAP) data.

Warm inflation with backreaction: a stochastic approach

I study a stochastic approach for warm inflation considering backreaction of the metric with the fluctuations of the matter field. This formalism takes into account the local inhomogeneities of the spacetime in a globally flat Friedmann-Robertson-Walker metric. The stochastic equations for the fluctuations of the matter field and metric are obtained. Finally, the dynamics for the amplitude of these fluctuations in a power-law expansion for the universe are examined.

Metric fluctuations and their evolution during inflation

Abstract.We discuss the evolution of the fluctuations in a symmetric

Gauge-invariant fluctuations of the metric in stochastic inflation

phi_{mathrm {c}}