Vacuum Sampling in the Landscape during Inflation

Abstract

We consider the phenomenological consequences of sampling multiple vacua during inflation motivated by an enormous landscape. A generic consequence of this sampling is the formation of domain walls, characterized by the scale $\mu$ of the barriers that partition the accessed vacua. We find that the success of Big Bang Nucleosynthesis (BBN) implies $\mu \text{gsim}10$ TeV, as long as the sampled vacua have a non-degeneracy larger than $\mathcal{O}({\mathrm{MeV}}^4)$. Otherwise, the walls will dominate and eventually form black holes that must reheat the universe sufficiently for BBN to take place; in this case, we obtain $\mu \text{gsim}10^{-5}{M}_P$. These black holes are not allowed to survive and contribute to cosmic dark matter density.

Comments: 4 pages. Abstract changed. New results and conclusion added