Closed String Thermodynamics and a Blue Tensor Spectrum

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.

6 pages, 3 figures, references added

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Cited by in corpus (9)

• Blue Tensor Spectrum from Particle Production during Inflation
• Blue-tilted Tensor Spectrum and Thermal History of the Universe
• Observational implications of mattergenesis during inflation
• Neutrinos and dark energy after Planck and BICEP2: data consistency tests and cosmological parameter constraints
• Spectral distortions from the dissipation of tensor perturbations
• Inflation and Alternatives with Blue Tensor Spectra
• Dynamical Fractional Chaotic Inflation -- Dynamical Generation of a Fractional Power-Law Potential for Chaotic Inflation
• Compensation for large tensor modes with iso-curvature perturbations in CMB anisotropies
• Linking the BICEP2 result and the hemispherical power asymmetry through spatial variation of $r$