Primordial Black Holes from Higgs Vacuum Instability: Avoiding
  Fine-tuning through an Ultraviolet Safe Mechanism
  We have recently proposed the idea that dark matter in our universe is formed
by primordial black holes generated by Standard Model Higgs fluctuations during
inflation and thanks to the fact that the Standard Model Higgs potential
develops an instability at a scale of the order of $10^{11}$ GeV. In this
sense, dark matter does not need any physics beyond the Standard Model,
although the mechanism needs fine-tuning to avoid the overshooting of the Higgs
into the dangerous AdS vacuum. We show how such fine-tuning can be naturally
avoided by coupling the Higgs to a very heavy scalar with mass $\gg 10^{11}$
GeV that stabilises the potential in the deep ultraviolet, but preserving the
basic feature of the mechanism which is built within the Standard Model.
