Effective Lagrangians in Quantum Electrodynamics

Abstract

With these notes we would like to provide an introduction to the subject of effective Lagrangians for quantum electrodynamics (QED). Although this topic is interesting in its own right, it also pro- vides us with an example of several important calculational tech- niques of QED which are usually not found in standard texts. Moreover, studying vacuum problems in QED, where matters are fairly well understood, can be a helpful preparation for similar considerations in quantum chromodynamics and other more compli- cated theories. In contrast to the latter, electrodynamics has the advantage that many calculations can still be done analytically.