How particle collisions increase the rate of accretion from the   cosmological background onto primordial black holes in braneworld cosmology
  It is shown that, contrary to the widespread opinion, particle collisions considerably increase accretion rate from the cosmological background onto 5D primordial black holes formed during the high-energy phase of the Randall-Sundrum Type II braneworld scenario. Increase of accretion rate leads to much tighter constraints on initial primordial black hole mass fraction imposed by the critical density limit and measurements of high-energy diffuse photon background and antiproton excess. 
V.V. Tikhomirov and Y.A. Tsalkou