6 research outputs found
Is exponential gravity a viable description for the whole cosmological history?
Here we analysed a particular type of gravity, the so-called
exponential gravity which includes an exponential function of the Ricci scalar
in the action. Such term represents a correction to the usual Hilbert-Einstein
action. By using Supernovae Ia, Barionic Acoustic Oscillations, Cosmic
Microwave Background and data, the free parameters of the model are well
constrained. The results show that such corrections to General Relativity
become important at cosmological scales and at late-times, providing an
alternative to the dark energy problem. In addition, the fits do not determine
any significant difference statistically with respect to the CDM
model. Finally, such model is extended to include the inflationary epoch in the
same gravitational Lagrangian. As shown in the paper, the additional terms can
reproduce the inflationary epoch and satisfy the constraints from Planck data.Comment: 20 pages, 6 figures, analysis extended, version published in EPJ
Constant roll inflation in multifield models
Constant roll inflation is analyzed in the presence of multi scalar fields
which are assumed to be described by a constant roll rate each. The different
cases are studied and the corresponding potentials are reconstructed. The exact
solutions are obtained, which show a similar behaviour to the single scalar
field model. For one of the cases analyzed in the paper, the so-called
adiabatic field also constant rolls while entropy perturbations become null,
while the second case may lead to non-adiabatic perturbations. Both cases can
fit well the Planck data by assuming the appropriate values for the free
parameters of the models.Comment: 13 pages, 4 figure