HEISENBERG–EULER EFFECTIVE LAGRANGIANS: BASICS AND EXTENSIONS

I present a pedagogical review of Heisenberg–Euler effective Lagrangians, beginning with the original work of Heisenberg and Euler, and Weisskopf, for the one loop effective action of quantum electrodynamics in a constant electromagnetic background field, and then summarizing some of the important applications and generalizations to inhomogeneous background fields, nonabelian backgrounds, and higher loop effective Lagrangians.