Features of the inflaton potential and the power spectrum of
  cosmological perturbations
  We discuss features of the inflaton potential that can lead to a strong
enhancement of the power spectrum of curvature perturbations. We show that a
steep decrease of the potential induces an enhancement of the spectrum by
several orders of magnitude, which may lead to the production of primordial
black holes. The same feature can also create a distinctive oscillatory pattern
in the spectrum of gravitational waves generated through the scalar
perturbations at second order. We study the additive effect of several such
features. We analyse a simplified potential, but also discuss the possible
application to supergravity models.
