Inflation in Weyl Scaling Invariant Gravity with $R^3$ Extensions

Abstract

The cosmological observations of cosmic microwave background and large-scale structure indicate that our universe has a nearly scaling invariant power spectrum of the primordial perturbation. However, the exact origin for this primordial spectrum is still unclear. Here, we propose the Weyl scaling invariant $R^2+R^3$ gravity that gives rise to inflation that is responsible for the primordial perturbation in the early universe. We develop both analytic and numerical treatments on inflationary observables, and find this model gives a distinctive scalar potential that can support two different patterns of inflation. The first one is similar to that occurs in the pure $R^2$ model, but with a wide range of tensor-to-scalar ratio $r$ from $\mathcal{O}(10^{-4})$ to $\mathcal{O}(10^{-2})$. The other one is a new situation with not only slow-roll inflation but also a short stage of oscillation-induced accelerating expansion. Both patterns of inflation have viable parameter spaces that can be probed by future experiments on cosmic microwave background and primordial gravitational waves.

26 pages, 6 figures, match the published version in Phys.Rev.D

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Cited by in corpus (7)

• The $R^2$-Higgs inflation: $R^3$ contribution and preheating after ACT and SPT data
• Gravitational Waves from Preheating in Inflation with Weyl Symmetry
• Linear dynamics and classical tests of the gravitational quantum field theory
• Observational Constraints on Extended Starobinsky and Weyl Gravity Model of Inflation
• Purely gravitational dark matter production in warm inflation
• Inflation in light of ACT/SPT: A new perspective from Weyl gravity
• Inflationary assessment of $F(\mathcal{R},\tilde{\mathcal{R}})$ Einstein-Cartan models