Universal upper bound on the inflationary energy scale from the trans-Planckian censorship conjecture

2019/10/31 by Shuntaro Mizuno, Shinji Mukohyama, Shi Pi +2 · 1 citation
Mathematics · Physics and Astronomy · #Black Holes and Theoretical Physics #Censorship #Combinatorics #Conjecture #Cosmic censorship hypothesis #Cosmology and Gravitation Theories #Mathematical analysis #Mathematics #Philosophy #Physics #Theology #Theoretical physics #Upper and lower bounds #advanced mathematical theories #astro-ph.CO #gr-qc #hep-th

paper · pdf · doi:10.1103/physrevd.102.021301

published as Phys. Rev. D 102, 021301 (2020) · 7 pages, 4 figures

openalex created_date 2019/10/18 · arxiv created 2020/07/21 · openalex publication_date 2020/07/21 · arxiv updated 2020/07/29 · openalex updated_date 2026/08/05

Abstract

We study the constraint on the inflationary energy scale from the recently proposed trans-Planckian censorship conjecture (TCC). We find a universal upper bound on the inflationary Hubble expansion rate H_inf which is solely determined by the reheating temperature T_rh: H_inf/M_Pl\ensuremath\lesssimT₀/T_rh, where T₀ is the photon temperature today. The upper limit can be saturated by a postinflationary oscillatory stage with the critical equation-of-state parameter w\ensuremath≈\ensuremath-1/3, or by an inflation model with multiple stages. In the lowest reheating temperature required for big bang nucleosynthesis, the upper bound on the tensor-to-scalar ratio r at the CMB scales is r\ensuremath\lesssim10^\ensuremath-8, which can be realized in many string-inspired inflation models.

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