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Universe 2016, 2(3), 20; doi:10.3390/universe2030020

Warm Inflation

Art and Design, Faculty of Technology, Oslo and Akershus University College of Applied Sciences, P.O. Box 4 St., Olavs Plass, NO-0130 Oslo, Norway
Academic Editors: Elias C. Vagenas and Lorenzo Iorio
Received: 25 July 2016 / Revised: 24 August 2016 / Accepted: 27 August 2016 / Published: 6 September 2016
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Abstract

I show here that there are some interesting differences between the predictions of warm and cold inflation models focusing in particular upon the scalar spectral index n s and the tensor-to-scalar ratio r. The first thing to be noted is that the warm inflation models in general predict a vanishingly small value of r. Cold inflationary models with the potential V = M 4 ( ϕ / M P ) p and a number of e-folds N = 60 predict δ n s C 1 n s ( p + 2 ) / 120 , where n s is the scalar spectral index, while the corresponding warm inflation models with constant value of the dissipation parameter Γ predict δ n s W = [ ( 20 + p ) / ( 4 + p ) ] / 120 . For example, for p = 2 this gives δ n s W = 1.1 δ n s C . The warm polynomial model with Γ = V seems to be in conflict with the Planck data. However, the warm natural inflation model can be adjusted to be in agreement with the Planck data. It has, however, more adjustable parameters in the expressions for the spectral parameters than the corresponding cold inflation model, and is hence a weaker model with less predictive force. However, it should be noted that the warm inflation models take into account physical processes such as dissipation of inflaton energy to radiation energy, which is neglected in the cold inflationary models. View Full-Text
Keywords: General relativity; Cosmology; The inflationary era General relativity; Cosmology; The inflationary era
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Grøn, Ø. Warm Inflation. Universe 2016, 2, 20.

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