Strengthening the TCC Bound on Inflationary Cosmology

Abstract: We show that the constraints which follow from the {\it Trans-Planckian Censorship Conjecture} for inflationary cosmology can be strengthened if the pre-inflationary universe was dominated by radiation. The resulting upper bound on the energy scale of inflation is $\eta \sim 10^4 {\rm GeV}$, close to the scale accessible to accelerator experiments.