19 research outputs found
Are Kaluza-Klein modes enhanced by parametric resonance?
We study parametric amplification of Kaluza-Klein (KK) modes in a higher
-dimensional generalized Kaluza-Klein theory, which was originally
considered by Mukohyama in the narrow resonance case. It was suggested that KK
modes can be enhanced by an oscillation of a scale of compactification by the
-dimensional sphere and by the direct product . We extend this past work to the more general case where
initial values of the scale of compactification and the quantum number of the
angular momentum of KK modes are not small. We perform analytic approaches
based on the Mathieu equation as well as numerical calculations, and find that
the expansion of the universe rapidly makes the KK field deviate from
instability bands. As a result, KK modes are not enhanced sufficiently in an
expanding universe in these two classes of models.Comment: 15 pages, 5 figure
Particle production in the oscillating inflation model
We investigate the particle production of a scalar field coupled to an
inflaton field () in the {\it oscillating inflation}
model, which was recently proposed by Damour and Mukhanov. Although the
fluctuation of the field can be effectively enhanced during a stage of
the oscillating inflation, the maximum fluctuation is suppressed as the
critical value which indicates the scale of the core part of the
inflaton potential decreases, in taking into account the back reaction effect
of created particles. As for the particle production, we find that
larger values of the coupling constant are required to lead to an efficient
parametric resonance with the decrease of , because an effective mass
of inflaton around the minimum of its potential becomes larger. However, it is
possible to generate the superheavy particle whose mass is greater than
GeV, which would result in an important consequence for the GUT
baryogenesis.Comment: 18 pages, 14 figure
Resonant particle production with non-minimally coupled scalar fields in preheating after inflation
We investigate a resonant particle production of a scalar field
coupled non-minimally to a spacetime curvature () as well as
to an inflaton field (). In the case of , effect assists -resonance in certain parameter regimes.
However, for , -resonance is not enhanced by
effect because of suppression effect as well as a back reaction effect.
If , the maximal fluctuation of produced -particle is
GeV for , which is larger than the minimally coupled case with .Comment: 33pages, 12figures. to appear in Physical Review
Inflation Dynamics and Reheating
We review the theory of inflation with single and multiple fields paying
particular attention to the dynamics of adiabatic and entropy/isocurvature
perturbations which provide the primary means of testing inflationary models.
We review the theory and phenomenology of reheating and preheating after
inflation providing a unified discussion of both the gravitational and
nongravitational features of multi-field inflation. In addition we cover
inflation in theories with extra dimensions and models such as the curvaton
scenario and modulated reheating which provide alternative ways of generating
large-scale density perturbations. Finally we discuss the interesting
observational implications that can result from adiabatic-isocurvature
correlations and non-Gaussianity.Comment: 51 pages, latex, 16 figures, version to appear in Reviews of Modern
Physic