Quantum Field Theory in Non-Invariant States

The talk is devoted to the study of quantum field theory in non-invariant states under non-stationary conditions and in the presence of strong external fields. We consider the dependence of the vacuum current in a constant strong electric field on the choice of the initial state, the dynamics of correlators after a global quench, the secular growth of loop corrections in de Sitter spacetime, and the question of the generation of an effective graviton mass due to quantum effects.