  We have recently suggested that tiny black holes can act as nucleation seeds
for the decay of the metastable Higgs vacuum. Previous results applied only to
the nucleation of thin-wall bubbles, and covered a very small region of
parameter space. This paper considers bubbles of arbitrary profile and reaches
the same conclusion: black holes seed rapid vacuum decay. Seeded and unseeded
nucleation rates are compared, and the gravitational back reaction of the
bubbles is taken into account. The evolution of the bubble interior is
described for the unseeded nucleation. Results are presented for the
renormalisation group improved Standard Model Higgs potential, and a simple
effective model representing new physics.
