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arXiv · 1403.4927

Closed String Thermodynamics and a Blue Tensor Spectrum

Robert H. Brandenberger·Ali Nayeri·Subodh P. Patil
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Abstract

The BICEP-2 team has reported the detection of primordial cosmic microwave background B-mode polarization, with hints of a suppression of power at large angular scales relative to smaller scales. Provided that the B-mode polarization is due to primordial gravitational waves, this might imply a blue tilt of the primordial gravitational wave spectrum. Such a tilt would be incompatible with standard inflationary models, although it was predicted some years ago in the context of a mechanism that thermally generates the primordial perturbations through a Hagedorn phase of string cosmology. The purpose of this note is to encourage greater scrutiny of the data with priors informed by a model that is immediately falsifiable, but which \textit{predicts} features that might be favoured by the data-- namely a blue tensor tilt with an induced and complimentary red tilt to the scalar spectrum, with a naturally large tensor to scalar ratio that relates to both.

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Robert H. Brandenberger, Ali Nayeri, Subodh P. Patil. 2014-03-26. Closed String Thermodynamics and a Blue Tensor Spectrum. https://doi.org/10.1103/physrevd.90.067301

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