2017/07/31 by T. Miranda, J. C. Fabris, O. F. Piattella · 44 citations
Physics and Astronomy · #Black Holes and Theoretical Physics #Class (philosophy) #Cosmology and Gravitation Theories #Curvature #Gravitation #Gravitational wave #Particle physics theoretical and experimental studies #Power index #Power law #Scalar (mathematics) #Spectral index #astro-ph.CO #gr-qc #hep-th
paper · pdf · doi:10.1088/1475-7516/2017/09/041
published in Journal of Cosmology and Astroparticle Physics 2017(09), 041 (Institute of Physics) · 17 pages, 8 figures. V2: full numerical reconstruction in the appendix. Accepted for publication in JCAP
openalex created_date 2017/07/31 · arxiv created 2017/09/19 · openalex publication_date 2017/09/28 · arxiv updated 2017/10/09 · openalex updated_date 2026/08/06
We show an analogy at high curvature between a f ( R ) = R + aR n − 1 + bR 2 theory and the α-Attractors. We calculate the expressions of the parameters a , b and n as functions of α and the predictions of the model f ( R ) = R + aR n − 1 + bR 2 on the scalar spectral index n s and the tensor-to-scalar ratio r . We find that the power law correction R n − 1 allows for a production of gravitational waves enhanced with respect to the one in the Starobinsky model, while maintaining a viable prediction on n s . We numerically reconstruct the full α-Attractors class of models testing the goodness of our high-energy approximation f ( R ) = R + aR n − 1 + bR 2 . Moreover, we also investigate the case of a single power law f ( R ) = γ R 2 − δ theory, with γ and δ free parameters. We calculate analytically the predictions of this model on the scalar spectral index n s and the tensor-to-scalar ratio r and the values of δ which are allowed from the current observational results. We find that −0.015 < δ < 0.016, confirming once again the excellent agreement between the Starobinsky model and observation.