335 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
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 which we are living in. In this work I
extend a previously introduced formalism, without the restriction of 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.Comment: 14 pages, no figures, to appear in Classical and Quantum Gravit
Decaying cosmological parameter in the early universe from NKK theory of gravity
Using a formalism recently introduced we study the decaying of the
cosmological parameter during the early evolution of an universe, whose
evolution is governed by a vacuum equation of state. We use a stochastic
approach in a nonperturbative treatment of the inflaton field from a Noncompact
Kaluza-Klein (NKK) theory, to study the evolution of energy density
fluctuations in the early universe.Comment: version accepted in Physics Letters
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