Massive Primordial Black Holes from Hybrid Inflation as Dark Matter and
  the seeds of Galaxies
  In this paper we present a new scenario where massive Primordial Black Holes
(PBH) are produced from the collapse of large curvature perturbations generated
during a mild waterfall phase of hybrid inflation. We determine the values of
the inflaton potential parameters leading to a PBH mass spectrum peaking on
planetary-like masses at matter-radiation equality and producing abundances
comparable to those of Dark Matter today, while the matter power spectrum on
scales probed by CMB anisotropies agrees with Planck data. These PBH could have
acquired large stellar masses today, via merging, and the model passes both the
constraints from CMB distortions and micro-lensing. This scenario is supported
by Chandra observations of numerous BH candidates in the central region of
Andromeda. Moreover, the tail of the PBH mass distribution could be responsible
for the seeds of supermassive black holes at the center of galaxies, as well as
for ultra-luminous X-rays sources. We find that our effective hybrid potential
can originate e.g. from D-term inflation with a Fayet-Iliopoulos term of the
order of the Planck scale but sub-planckian values of the inflaton field.
Finally, we discuss the implications of quantum diffusion at the instability
point of the potential, able to generate a swiss-cheese like structure of the
Universe, eventually leading to apparent accelerated cosmic expansion.
