1pm-2pm: Black holes and false vacuum decay

It is a common wisdom that impurities and inhomogeneities can accelerate first-order phase transitions and false vacuum decay. Black hole is an interesting example of spatial "impurity" and a source of quantum Hawking radiation. It is important to calculate accurately how black holes catalyse the decay of a metastable state, since our current, low-energy vacuum of the Standard Model is itself metastable, and since many cosmological models predict abundant production of small, hot primordial black holes. The challenge is that an evaporating black hole is not in thermal equilibrium with its environment, and standard Euclidean methods of calculating the decay rate are not justified. I will discuss progress made in calculating black hole induced vacuum decay from different initial states using toy models of dilaton black holes in two dimensions. In particular, I will show that the non-equilibrium initial state decays exponentially slower than the equilibrium one and its decay rate is exponentially suppressed at all black hole temperatures. This is expected to be true in four dimensions as well, and the precise suppression factor remains to be calculated.