Investigating formation condition of primordial black holes for   generalized initial perturbation profiles
  Primordial black holes (PBHs) are an important tool in cosmology to probe the primordial spectrum of small-scale curvature perturbations that reenter the cosmological horizon during radiation domination epoch. We numerically solve the evolution of spherically symmetric highly perturbed configurations to clarify the criteria of PBHs formation using a wide class of curvature profiles characterized by five parameters. It is shown that formation or non-formation of PBHs is determined essentialy by only two master parameters. 
Tomohiro Nakama, Tomohiro Harada, A. G. Polnarev, Jun'ichi Yokoyama
gr-qc