QFT on strongly curved backgrounds

Quantum field theory is one of the great achievements of modern physics, allowing for precise predictions of observables measured at particle colliders. But man shall not live by amplitudes on trivial backgrounds alone. In this talk I will aim to give an introduction to background field theories. For scattering in the presence of strong electromagnetic fields the standard perturbative methods break down. However, background field theory provides a framework to treat the background exactly, unveiling a range of new phenomena. We will go over the basics of background field theory and its connections to many-particle scattering, as well as some applications involving non-perturbative pair creation.