Pre-inflation and Trans-Planckian Censorship

TL;DR

This paper explores how a past-complete pre-inflationary phase can naturally set the initial conditions for inflationary perturbations consistent with the Trans-Planckian Censorship Conjecture, ensuring modes start in the Minkowski vacuum.

Contribution

It demonstrates that a past-complete pre-inflationary era can produce the Bunch-Davies initial state for perturbations while satisfying the TCC.

Findings

Perturbation modes behave as in Bunch-Davies state at inflation start

A past-complete pre-inflationary era can set initial conditions consistent with TCC

Modes with wavelengths larger than the Planck scale are well-behaved

Abstract

We investigate the implication of Trans-Planckian Censorship Conjecture (TCC) for the initial state of primordial perturbations. It is possible to set the state of perturbation modes in the infinite past as the Minkowski vacuum, only if the pre-inflationary era is past-complete. We calculate the evolution of the perturbation modes in such a pre-inflationary era and show that at the beginning of inflation the perturbation modes with wavelengths much shorter than the Hubble scale (but still larger than the Planck length scale) will behave as they are in the Bunch-Davis state. Therefore, a past-complete pre-inflationary evolution may automatically prepare the initial state required for the inflationary perturbations at the CMB window while obeying the TCC.