Trans-Planckian censorship, inflation and excited initial states for perturbations

Abstract

The recently proposed trans-Planckian censorship conjecture (TCC) seems to require that the energy scale of inflation is significantly lower than the Planck scale $(H_\text{inf}<10^{-20} \Mpl)$. This, in turn, implies that the tensor-to-scalar ratio for inflation is negligibly small, \textit{independent} of assumptions of slow-roll or even of having a single scalar field, thus ruling out inflation if primordial tensor modes are ever observed. After demonstrating the robustness and generality of these bounds, we show that having an excited initial state for cosmological perturbations seems to be a way out of this problem for models of inflation.

15 pages, comments welcome; typos corrected, refs added & minor revisions; v3: matches published version

References in corpus (10)

• Quantum Gravity at a Lifshitz Point
• On the Geometry of the String Landscape and the Swampland
• The Swampland: Introduction and Review
• Enhanced Non-Gaussianity from Excited Initial States
• A Note on Calm Excited States of Inflation
• Distance, de Sitter and Trans-Planckian Censorship conjectures: the status quo of Warm Inflation
• Warm brane inflation with an exponential potential: A consistent realization away from the swampland
• Trans-Planckian censorship and other swampland bothers addressed in warm inflation
• On the Tensor/Scalar Ratio in Inflation with UV Cutoff
• Tensor Non-Gaussianity Search: Current Status and Future Prospects

Cited by in corpus (9)

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• Trans-Planckian censorship and other swampland bothers addressed in warm inflation
• The trans-Planckian censorship conjecture from the swampland distance conjecture
• Trans-Planckian Censorship Conjecture and Non-thermal post-inflationary history
• Swampland dS conjecture in Mimetic $f(R,T)$ gravity
• Swampland conjectures in hybrid metric-Palatini gravity
• Trans-Planckian Censorship and Inflation in Grand Unified Theories
• Mass bound for primordial black hole from trans-Planckian censorship conjecture
• Is Trans-Planckian Censorship a Swampland Conjecture?