Inflation After False Vacuum Decay: New Evidence from BICEP2

Understand

Last year we argued that if slow-roll inflation followed the decay of a false vacuum in a large landscape, the steepening of the scalar potential between the inflationary plateau and the barrier generically leads to a potentially observable suppression of the scalar power spectrum at large distances.

• Here we revisit this analysis in light of the recent BICEP2 results.
• Assuming that both the BICEP2 B-mode signal and the Planck analysis of temperature fluctuations hold up, we find that the data now discriminate more sharply between our scenario and $\Lambda$CDM.
• Nonzero tensor modes exclude standard $\Lambda$CDM with notable but not yet conclusive confidence: at $\sim 3.8\,\sigma$ if $r\approx0.2$, or at $\sim 3.5\,\sigma$ if $r=0.15$.