On the Calculation of QED Amplitudes in a Constant Field
  It is explained how first-quantized worldline path integrals can be used as an efficient alternative to Feynman diagrams in the calculation of QED amplitudes and effective actions. The examples include the one-loop photon splitting amplitude, the two-loop Euler-Heisenberg Lagrangian, and the one-loop axial vacuum polarization tensor in a general constant electromagnetic field. 
Christian Schubert (LAPTH, Annecy-le-Vieux)