Relaxing the TCC Bound on Inflationary Cosmology?

Abstract

We demonstrate that the strict upper bounds on the energy scale of inflation and on the tensor-to-scalar ratio can be somewhat relaxed if we assume that - after an initial period of slow rolling when scales probed today in CMB experiments exit the Hubble radius - the equation of state of the background changes to correspond to an almost marginally accelerating universe. Constructing an actual model in which this happens appears, however, to be unnatural.

arXiv comment5 pages, no figures; a few minor algebra errors corrected, matches with the published version (European Journal of Physics C)

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• Swampland, Trans-Planckian Censorship and Fine-Tuning Problem for Inflation: Tunnelling Wavefunction to the Rescue
• Role of trans-Planckian modes in cosmology
• On the Trans-Planckian Censorship Conjecture and the Generalized Non-Minimal Coupling
• Unattainability of the Trans-Planckian regime in Nonlocal Quantum Gravity
• Creating Spatial Flatness by Combining String Gas Cosmology and Power Law Inflation
• Thermal, Trapped and Chromo-Natural Inflation in light of the Swampland Criteria and the Trans-Planckian Censorship Conjecture
• Unitarity Problems for an Effective Field Theory Description of Early Universe Cosmology
• Rejuvenating the hope of a swampland consistent inflated multiverse with tachyonic inflation in the high energy RS-II Braneworld
• Limitations of an Effective Field Theory Treatment of Early Universe Cosmology
• Swampland conjectures and single field inflation in non-standard cosmological scenarios
• Axion Monodromy Inflation, Trapping Mechanisms and the Swampland
• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme
• Large $r$ against Trans-Planckian Censorship in Scalar-Tensor Theory?
• Implications of single field inflation in general cosmological scenarios on the nature of dark energy given the swampland conjectures