2,059 research outputs found
Is Cosmological Constant Needed in Higgs Inflation?
The detection of B-mode shows a very powerful constraint to theoretical
inflation models through the measurement of the tensor-to-scalar ratio .
Higgs boson is the most likely candidate of the inflaton field. But usually,
Higgs inflation models predict a small value of , which is not quite
consistent with the recent results from BICEP2. In this paper, we explored
whether a cosmological constant energy component is needed to improve the
situation. And we found the answer is yes. For the so-called Higgs chaotic
inflation model with a quadratic potential, it predicts ,
with e-folds number , which is large enough to
overcome the problems such as the horizon problem in the Big Bang cosmology.
The required energy scale of the cosmological constant is roughly , which means a mechanism is still needed to solve the
fine-tuning problem in the later time evolution of the universe, e.g. by
introducing some dark energy component.Comment: 4 pages, 2 figure
K-Inflation in Noncommutative Space-Time
The power spectra of the scalar and tensor perturbations in the
noncommutative k-inflation model are calculated in this paper. In this model,
all the modes created when the stringy space-time uncertainty relation is
satisfied are generated inside the sound/Hubble horizon during inflation for
the scalar/tensor perturbations. It turns out that a linear term describing the
noncommutative space-time effect contributes to the power spectra of the scalar
and tensor perturbations. Confronting the general noncommutative k-inflation
model with latest results from \textit{Planck} and BICEP2, and taking and
as free parameters, we find that it is well consistent with
observations. However, for the two specific models, i.e. the tachyon and DBI
inflation models, it is found that the DBI model is not favored, while the
tachyon model lies inside the contour, if the e-folds number is
assumed to be around .Comment: 9 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1404.016
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