Inflation with two-form field: the production of primordial black holes
  and gravitational waves
  Antisymmetric tensor field (two-form field) is a ubiquitous component in
string theory and generally couples to the scalar sector through its kinetic
term. In this paper, we propose a cosmological scenario that the particle
production of two-form field, which is triggered by the background motion of
the coupled inflaton field, occurs at the intermediate stage of inflation and
generates the sizable amount of primordial black holes as dark matter after
inflation. We also compute the secondary gravitational waves sourced by the
curvature perturbation and show that the resultant power spectra are testable
with the future space-based laser interferometers.
