 Euler–Heisenberg Lagrangian

The Euler–Heisenberg Lagrangian is a effective field theory that describes the dynamics of electromagnetic fields in the presence of strong electric and magnetic fields taking into account the effects of quantum mechanics. It emerges from the study of quantum electrodynamics (QED) and encapsulates the nonlinear interactions of photons due to the pair production of electron-positron pairs in strong electromagnetic fields.