  We clarify under what conditions slow-roll inflation can continue almost
undisturbed, while briefly evolving through a (semi-classically) metastable
false vacuum. Furthermore, we look at potential signatures in the primordial
power spectrum that could point towards the existence of traversed metastable
false vacua. Interestingly, the theoretical constraints for the existence of
traversable metastable vacua imply that Planck should be able to detect the
resulting features in the primordial power spectrum. In other words, if Planck
does not see features this immediately implies the non-existence of metastable
false vacua rolled through during the inflationary epoch.

High Energy Physics - Theory;General Relativity and Quantum Cosmology