Particle creation from the quantum stress tensor

Understand

Among the different methods to derive particle creation, finding the quantum stress tensor expectation value gives a covariant quantity which can be used for examining the back-reaction issue.

• However this tensor also includes vacuum polarization in a way that depends on the vacuum chosen.
• Here we review different aspects of particle creation by looking at energy conservation and at the quantum stress tensor.
• It will be shown that in the case of general spherically symmetric black holes that have a \emph{dynamical horizon}, as occurs in a cosmological context, one cannot have pair creation on the horizon because this violates energy conservation.