On the Catalysis of the Electroweak Vacuum Decay by Black Holes at High
  Temperature
  We study the effect of primordial black holes on the classical rate of
nucleation of AdS regions within the standard electroweak vacuum at high
temperature. We find that the energy barrier for transitions to the new vacuum,
which determines the exponential suppression of the nucleation rate, can be
reduced significantly, or even eliminated completely, in the black-hole
background if the Standard Model Higgs is coupled to gravity through the
renormalizable term $\xi {\cal R} h^2$.
