Jump in fluid properties of inflationary universe to reconcile scalar and tensor spectra

Abstract

The recent detection of the primordial gravitational waves from the BICEP2 observation seems to be in tension with the upper bound on the amplitude of tensor perturbations from the PLANCK data. We consider a phenomenological model of inflation in which the microscopical properties of the inflationary fluid such as the equation of state $w$ or the sound speed $c_s$ jump in a sharp manner. We show that the amplitude of the scalar perturbations is controlled by a non-trivial combination of $w$ and $c_s$ before and after the phase transition while the tensor perturbations remains nearly intact. With an appropriate choice of the fluid parameters $w$ and $c_s$ one can suppress the scalar perturbation power spectrum on large scales to accommodate a large tensor amplitude with $r=0.2$ as observed by BICEP2 observation.

arXiv comment12 pages, 13 figures

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Cited by in corpus (8)

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• Untangling features in the primordial spectra
• Pre-inflationary primordial perturbations
• Oscillating modulation to B-mode polarization from varying propagating speed of primordial gravitational waves
• Effect of transitions in the Planck mass during inflation on primordial power spectra
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