Types of quantum field thories
A classical field theory with action functional having the standard kinetic term non-derivative interactions has stable, time-independent solutions where all fields are constant on a value that is a local minimum of the interaction term potential energy (if any).
In the corresponding quantum field theory, however, a state that is initially concentrated this way on a local minimum which is not also a global minimum is not time-independent, but will exhibit quantum tunneling? behaviour by which the fields “tunnel” through the local potential barrier into the global minimum. Therefore one speaks of a false vacuum in this case.
The classical articles are