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Title: Suppressing the impact of a high tensor-to-scalar ratio on the temperature anisotropies

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 ≅ 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 n{sub s}. 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 n{sub s} 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 χ{sup 2} improves by ∼ 7.5 over that of the constant running, at the cost of onemore » 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.« less

Authors:
 [1];  [2];  [3]
  1. Theoretical Physics, Blackett Laboratory, Imperial College, London, SW7 2BZ (United Kingdom)
  2. School of Physics and Astronomy, University of Minnesota, Minneapolis, 55455 (United States)
  3. Department of Physics, University of Massachusetts, Amherst, MA 01003 (United States)
Publication Date:
OSTI Identifier:
22373472
Resource Type:
Journal Article
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2014; Journal Issue: 07; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1475-7516
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; CORRELATIONS; DUSTS; ERRORS; FLUCTUATIONS; POLARIZATION; SCALARS; SIGNALS; SPECTRA; TENSORS; VELOCITY

Citation Formats

Contaldi, Carlo R., Peloso, Marco, and Sorbo, Lorenzo. Suppressing the impact of a high tensor-to-scalar ratio on the temperature anisotropies. United States: N. p., 2014. Web. doi:10.1088/1475-7516/2014/07/014.
Contaldi, Carlo R., Peloso, Marco, & Sorbo, Lorenzo. Suppressing the impact of a high tensor-to-scalar ratio on the temperature anisotropies. United States. https://doi.org/10.1088/1475-7516/2014/07/014
Contaldi, Carlo R., Peloso, Marco, and Sorbo, Lorenzo. 2014. "Suppressing the impact of a high tensor-to-scalar ratio on the temperature anisotropies". United States. https://doi.org/10.1088/1475-7516/2014/07/014.
@article{osti_22373472,
title = {Suppressing the impact of a high tensor-to-scalar ratio on the temperature anisotropies},
author = {Contaldi, Carlo R. and Peloso, Marco and Sorbo, Lorenzo},
abstractNote = {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 ≅ 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 n{sub s}. 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 n{sub s} 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 χ{sup 2} 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.},
doi = {10.1088/1475-7516/2014/07/014},
url = {https://www.osti.gov/biblio/22373472}, journal = {Journal of Cosmology and Astroparticle Physics},
issn = {1475-7516},
number = 07,
volume = 2014,
place = {United States},
year = {Tue Jul 01 00:00:00 EDT 2014},
month = {Tue Jul 01 00:00:00 EDT 2014}
}