Variations of Starobinsky inflation in closed universes

Research output: Unpublished contribution to conferencePoster

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Abstract

Inflation, first proposed by Alan Guth in 1979, describes a period of exponential expansion in the Early Universe, which has become an integral part of modern Cosmology. Its main purpose is to solve several problems in the Standard Model of Cosmology while also providing an explanation for the formation of large-scale structures in the Universe. There are various inflationary models, and they can be probed by Cosmic Microwave Background (CMB) and Gravitational Wave experiments. One of the most promising inflationary models is Starobinsky inflation, which has been supported by recent Planck data. Starobinsky inflation is often reduced to R2 inflation, involving only the Ricci scalar R and R2. However, the full model contains additional terms called higher derivative corrections that become significant in the Early Universe and can affect the pattern of primordial perturbations imprinted in the CMB. Unfortunately, these extra terms can also give rise to unwanted side effects. Therefore, we consider a specific set of higher curvature corrections, which are less trivial than those of the simplified R2 model, while still avoiding the undesired side effects that arise in the full Starobinsky model. When
studying inflationary models, choosing realistic initial conditions is crucial. In this study, we select initial conditions based on the Hartle-Hawking No Boundary Wave Proposal (NBWP), which describes the Big Bang quantum mechanically and selects closed universes. Motivated by the NBWP, we study the higher curvature corrections to R2 inflation in closed FLRW universes, in contrast to previous studies that considered flat FLRW universes. Our investigation explores how the higher curvature corrections
interact with the curvature of the Universe and their possible impact on the CMB spec-
trum. Our findings highlight the significance of this interplay, as it may solve the low ℓ
anomaly, a persistent challenge in the Standard Model of Cosmology. Furthermore, the
next generation of CMB experiments will be able to probe these higher order corrections and might provide us with experimental validation of this theoretical model.

Keywords

  • Inflation

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