Trans-Planckian censorship and inflationary cosmology

Abstract

We study the implications of the recently proposed Trans-Planckian censorship conjecture (TCC) for early Universe cosmology and in particular inflationary cosmology. The TCC leads to the conclusion that if we want inflationary cosmology to provide a successful scenario for cosmological structure formation, the energy scale of inflation has to be lower than 109 GeV. Demanding the correct amplitude of the cosmological perturbations then forces the generalized slow-roll parameter ϵ of the model to be very small (<10-31). This leads to the prediction of a negligible amplitude of primordial gravitational waves. For slow-roll inflation models, it also leads to severe fine-tuning of initial conditions.