skip to main content

SciTech ConnectSciTech Connect

Title: Reconstructing the inflationary f(R) from observations

The BICEP2 collaboration has recently released data showing that the scalar-to-tensor ratio r is much larger than expected. The immediate consequence, in the context of f(R) gravity, is that the Starobinsky model of inflation is ruled out since it predicts a value of r much smaller than what is observed. Of course, the BICEP2 data need verification, especially from Planck with which there is some tension, therefore any conclusion seems premature. However, it is interesting to ask what would be the functional form of f(R) in the case when the value of r is different from the one predicted by the Starobinsky model. In this paper, we show how to determine the form of f(R), once the slow-roll parameters are known with some accuracy. The striking result is that, for given values of the scalar spectral index n{sub S} and r, the effective Lagrangian has the form f(R)=R{sup ζ}, where ζ=2-ε and |ε||| 1. Therefore, it appears that the inflationary phase of the Universe is best described by a R{sup 2} theory, with a small deviation that, as we show, can be obtained by quantum corrections.
Authors:
; ; ;  [1]
  1. Dipartimento di Fisica, Università di Trento, via Sommarive 14, Trento, 38123 (Italy)
Publication Date:
OSTI Identifier:
22373413
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 08; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCURACY; CORRECTIONS; COSMOLOGICAL INFLATION; GRAVITATION; LAGRANGIAN FUNCTION; SCALARS; TENSORS; UNIVERSE