Strengthening the TCC Bound on Inflationary Cosmology

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.
Comment: 5 pages, 1 figure; v2: references added and updated, v3: minor clarifications added