Non-Standard Cosmological Models and the trans-Planckian Censorship Conjecture

Abstract

The trans-Planckian censorship conjecture (TCC) puts an upper bound on the life-time of de Sitter spacetimes. It has immediate consequences for inflationary cosmology. In the standard paradigm, the universe has experienced a single stage of inflation and follows a thermal history. Then, the TCC puts an upper bound on the Hubble parameter during inflation $H_{\inf }$ around $0.1$ GeV. Consequently, it implies a severe fine-tuning in initial condition for inflation and non-detection of primordial gravitational waves. In this note, we study non-standard cosmological paradigms with non-thermal history and/or multiple stages of inflations. It is motivated by string theory compactifications and axiverse scenarios in which the modulus/axion fields are effective in the early universe. In early matter domination the TCC bound on $H_{\inf }$ can be raised up to 3 orders of magnitude. In multiple inflationary scenarios the upper bound on the observable inflation can be raised up $10^{14}$ GeV to touch the Planck 2018 bound.

4 pages, 3 figures, v2: references added, plots added for illustration, typos corrected, v3:published version

References in corpus (3)

• The Swampland: Introduction and Review
• Dark energy from the string axiverse
• Explaining the Electroweak Scale and Stabilizing Moduli in M Theory

Cited by in corpus (13)

• Intermittent null energy condition violations during inflation and primordial gravitational waves
• Is the NANOGrav signal a hint of dS decay during inflation?
• Trans-Planckian censorship of multistage inflation and dark energy
• Strengthening the TCC Bound on Inflationary Cosmology
• Brane inflation and Trans-Planckian censorship conjecture
• 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
• 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
• Limitations of an Effective Field Theory Treatment of Early Universe Cosmology
• 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?