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

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• Trans-Planckian Censorship Conjecture and Non-thermal post-inflationary history
• Reissner-Nordström black holes surrounded by perfect fluid dark matter: testing the viability of weak gravity conjecture and weak cosmic censorship conjecture simultaneously
• Weak Cosmic Censorship and Weak Gravity Conjectures in CFT Thermodynamics
• Swampland dS conjecture in Mimetic $f(R,T)$ gravity
• Trans-Planckian Censorship and Inflation in Grand Unified Theories
• Swampland conjectures in hybrid metric-Palatini gravity
• Brane inflation and Trans-Planckian censorship conjecture
• Mass bound for primordial black hole from trans-Planckian censorship conjecture
• On the Trans-Planckian Censorship Conjecture and the Generalized Non-Minimal Coupling
• Is Trans-Planckian Censorship a Swampland Conjecture?
• Further Refining Swampland dS Conjecture in Mimetic f(G) Gravity
• Rejuvenating the hope of a swampland consistent inflated multiverse with tachyonic inflation in the high energy RS-II Braneworld
• Lorentz violating inflation and the Swampland
• Swampland conjectures and single field inflation in non-standard cosmological scenarios
• Expansion-contraction duality breaking in a Planck-scale sensitive cosmological quantum simulator
• Cosmic-Quantum Connections: Assessing the Viability of Weak Gravity and Weak Cosmic Censorship Conjectures in Kerr-Newman-Kiselev-Letelier Black Hole
• Hitchhiker's Guide to the Swampland: The Cosmologist's Handbook to the string-theoretical Swampland Programme
• Graviton-Photon Oscillations as a Probe of Quantum Gravity
• Stability of Extremal Black Holes and Weak Cosmic Censorship Conjecture in Kiselev Spacetime
• The Role of Torsion in Trans-Planckian Physics
• Stochastic gravitational wave background anisotropies from inflation with non-Bunch-Davies states
• Implications of single field inflation in general cosmological scenarios on the nature of dark energy given the swampland conjectures
• Cosmological Implications of Thermodynamic Split Conjecture