  Primordial black holes can be produced by a long range attractive fifth force
stronger than gravity, mediated by a light scalar field interacting with
nonrelativistic "heavy" particles. As soon as the energy fraction of heavy
particles reaches a threshold, the fluctuations rapidly become nonlinear. The
overdensities collapse into black holes or similar screened objects, without
the need for any particular feature in the spectrum of primordial density
fluctuations generated during inflation. We discuss whether such primordial
black holes can constitute the total dark matter component in the Universe.
