Suppressing the impact of a high tensor-to-scalar ratio on the temperature anisotropies
File(s)
Accepted version
Author(s)
Contaldi, CR
Peloso, Marco
Sorbo, Lorenzo
Type
Journal Article
Abstract
The BICEP2 collaboration has reported a strong B mode signal in the CMB polarization, which is well fit by a tensor-to-scalar ratio of r sime 0.2. This is greater than the upper limit r < 0.11 obtained from the temperature anisotropies under the assumption of a constant scalar spectral index ns. This discrepancy can be reduced once the statistical error and the contamination from polarized dust are accounted for. If however a large value for r will be confirmed, it will need to be reconciled with the temperature anisotropies data. The most advocated explanation involves a variation of ns with scales (denoted as running) that has a magnitude significantly greater than the generic slow roll predictions. We instead study the possibility that the large scale temperature anisotropies are not enhanced because of a suppression of the scalar power at large scales. Such a situation can be achieved for instance by a sudden change of the speed of the inflaton (by about 14%), and we show that it fits the temperature anisotropies and polarization data considerably better than a constant running (its χ2 improves by ~ 7.5 over that of the constant running, at the cost of one more parameter). We also consider the possibility that the large scale temperature fluctuations are suppressed by an anti-correlation between tensor and scalar modes. Unfortunately, while such effect does affect the temperature fluctuations at large scales, it does not affect the temperature power spectrum and cannot, therefore, help in reconciling a large value of r with the limits from temperature fluctuations.
Date Issued
2014-07-08
Date Acceptance
2014-06-18
Citation
Journal of Cosmology and Astroparticle Physics, 2014, 2014 (7), pp.1-14
ISSN
1475-7516
Publisher
IOP Publishing
Start Page
1
End Page
14
Journal / Book Title
Journal of Cosmology and Astroparticle Physics
Volume
2014
Issue
7
Copyright Statement
© 2014 IOP Publishing Ltd and Sissa Medialab srl. This is an author-created, un-copyedited version of an article accepted for publication in Journal of Cosmology and Astroparticle Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at [insert hyperlinked DOI].
Sponsor
Science and Technology Facilities Council (STFC)
Science and Technology Facilities Council (STFC)
Identifier
https://iopscience.iop.org/article/10.1088/1475-7516/2014/07/014
Grant Number
ST/J000353/1
ST/L00044X/1
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
Physics, Particles & Fields
Physics
inflation
CMBR theory
RUNNING SPECTRAL INDEX
INFLATION
SUPERGRAVITY
UNIVERSE
POWER
MODEL
astro-ph.CO
astro-ph.CO
hep-ph
hep-th
0201 Astronomical and Space Sciences
0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
Nuclear & Particles Physics
Publication Status
Published
Article Number
ARTN 014
Date Publish Online
2014-07-08