Primordial Black Holes and the String Swampland
  The "swampland conjectures" have been recently suggested as a set of criteria
to assess if effective field theories (EFTs) are consistent with a quantum
gravity embedding. Such criteria, which restrict the behavior of scalar fields
in the theory, have strong implications for cosmology in the early universe. As
we demonstrate, they will also have direct consequences for formation of
primordial black holes (PBHs) and dark matter (DM).
