Starobinsky inflation beyond the leading order

Abstract

The Starobinsky model of cosmological inflation in four spacetime dimensions is reviewed with the emphasis on impact of quantum gravity corrections. As a specific example of the quantum corrections, the Grisaru-Zanon quartic curvature terms in the gravitational effective action of closed superstrings are chosen. Those quartic curvature terms are compared to the Bel-Robinson tensor squared in a flat Friedman universe, and the upper bound on the effective string coupling constant is found by demanding unitarity (causality) and the absence of ghosts. It is found that the quantum corrections to the observables (tilts) of the cosmic microwave background radiation in the Starobinsky inflation may be of the same order of magnitude as the next-to-next-to-next classical contributions in the Starobinsky model with respect to the inverse powers of the e-folding number at the horizon crossing.

13 pages, no figures, LaTeX; a reference added; misprints corrected

References in corpus (5)

• BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season
• The Swampland: Introduction and Review
• On Inflation with Non-minimal Coupling
• Towards Axionic Starobinsky-like Inflation in String Theory
• Einstein-Grisaru-Zanon gravity

Cited by in corpus (6)

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• Inflation in $F(R)$ gravity models revisited after ACT
• Primordial power spectrum at N3LO in effective theories of inflation
• Precision predictions of Starobinsky inflation with self-consistent Weyl-squared corrections
• Effect of $R^2$ on the stability of de Sitter solution of the generalized Einsteinian cubic gravity
• Inflationary assessment of $F(\mathcal{R},\tilde{\mathcal{R}})$ Einstein-Cartan models