Primordial Black Holes Formation from Particle Production during
  Inflation
  We study the possibility that particle production during inflation can source
the required power spectrum for dark matter (DM) primordial black holes (PBH)
formation. We consider the scalar and the gauge quanta production in inflation
models, where in the latter case, we focus in two sectors: inflaton coupled i)
directly and ii) gravitationally to a $U(1)$ gauge field. We do not assume any
specific potential for the inflaton field. Hence, in the gauge production case,
in a model independent way we show that the non-production of DM PBHs puts
stronger upper bound on the particle production parameter. Our analysis show
that this bound is more stringent than the bounds from the bispectrum and the
tensor-to-scalar ratio derived by gauge production in these models. In the
scenario where the inflaton field coupled to a scalar field, we put an upper
bound on the amplitude of the generated scalar power spectrum by non-production
of PBHs. As a by-product we also show that the required scalar power spectrum
for PBHs formation is lower when the density perturbations are non-Gaussian in
comparison to the Gaussian density perturbations.
