Naturally large tensor-to-scaalar ratio in inflation

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Title:	Naturally large tensor-to-scaalar ratio in inflation
Authors:	Liu, Guo-Chin;Ng, Kin-Wang;Wang, I.-Chin
Date:	2014-09-12
Issue Date:	2016-01-06 11:27:45 (UTC+8)
Abstract:	Recently, BICEP2 measurements of the cosmic microwave background (CMB) B-mode polarization at degree angular scales has indicated the presence of tensor modes with a high tensor-to-scalar ratio of r=0.2 when assuming nearly scale-invariant tensor and scalar spectra, although the signal may be contaminated by dust emission, as implied by recent Planck polarization data. This result is in conflict with the Planck best-fit lambda cold dark model with r<0.11. Because the inflaton has to interact with other fields to convert its potential energy into radiation to reheat the Universe, the interacting inflaton may result in a suppression of the scalar spectrum at large scales. This suppression has been used to explain the observed low quadrupole in the CMB anisotropy. In this paper, we show that a combination of the tensor modes measured by BICEP2 and the large-scale suppressed scalar modes contributes to the CMB anisotropy in such a way that the resultant CMB anisotropy and polarization power spectra are consistent with both Planck and BICEP2 data. We also project our findings to cases in which r may become reduced in future CMB polarization measurements.
Relation:	Physical Review D 90(10), 103531
DOI:	10.1103/PhysRevD.90.103531
Appears in Collections:	[Graduate Institute & Department of Physics] Journal Article

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