10,011 research outputs found
Warm inflation with back - reaction: a stochastic approach
I study a stochastic approach for warm inflation considering back - reaction
of the metric with the fluctuations of matter field. This formalism takes into
account the local inhomogeneities fo the spacetime in a globally flat Friedmann
- Robertson - Walker metric. The stochastic equations for the fluctuations of
the matter field and the metric are obtained. Finally, the dynamics for the
amplitude of these fluctuations in a power - law expansion for the universe are
examined.Comment: minor changes, 6 pages, no figures, accepted for publication in
Classical and Quantum Gravit
Fresh inflation and decoherence of super Hubble fluctuations
I study a stochastic approach to the recently introduced fresh inflation
model for super Hubble scales. I find that the state loses its coherence at the
end of the fresh inflationary period as a consequence of the damping of the
interference function in the reduced density matrix. This fact should be a
consequence of a) the relative evolutions of both the scale factor and the
horizon and b) the additional thermal and dissipative effects. This implies a
relevant difference with respect to supercooled inflationary scenarios which
require a very rapid expansion of the scale factor to give the decoherence of
super Hubble fluctuations.Comment: version with minor changes. To appear in Phys. Rev.
Thermodynamical properties of metric fluctuations during inflation
I study a thermodynamical approach to scalar metric perturbations during the
inflationary stage. In the power-law expanding universe here studied, I find a
negative heat capacity as a manifestation of superexponential growing for the
number of states in super Hubble scales. The power spectrum depends on the
Gibbons-Hawking and Hagedorn temperatures.Comment: 7 pages, no figures (accepted to publication in General Relativity
and Gravitation
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.Comment: Version accepted in EPJC with new title. 11 pages, no figure
Warm inflation and scalar perturbations of the metric
A second-order expansion for the quantum fluctuations of the matter field was
considered in the framework of the warm inflation scenario. The friction and
Hubble parameters were expended by means of a semiclassical approach. The
fluctuations of the Hubble parameter generates fluctuations of the metric.
These metric fluctuations produce an effective term of curvature. The power
spectrum for the metric fluctuations can be calculated on the infrared sector.Comment: 10 pages, no figures, to be published in General Rel. and Gravitatio
Fresh inflation: a warm inflationary model from a zero temperature initial state
A two-components mixture fluid which complies with the gamma law is
considered in the framework of inflation with finite temperature. The model is
developed for a quartic scalar potential without symmetry breaking. The
radiation energy density is assumed to be zero when inflation starts and
remains below the GUT temperature during the inflationary stage. Furthermore,
provides the necessary number of e-folds and sufficient radiation energy
density to GUT baryogenesis can take place near the minimum energetic
configuration.Comment: 11 pages, no figures, to be published in Phys. Rev.
Metric fluctuations and its evolution during inflation
W discuss the evolution of the fluctuations in a symmetric
-exponential potential which provides a power-law expansion during
inflation using both, the gauge invariant field and the Sasaki-Mukhanov
field.Comment: version accepted in EPJ
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