An Introduction to the Worldline Technique for Quantum Field Theory   Calculations
  These two lectures give a pedagogical introduction to the ``string-inspired'' worldline technique for perturbative calculations in quantum field theory. This includes an overview over the present range of its applications. Several examples are calculated in detail, up to the three-loop level. The emphasis is on photon scattering in quantum electrodynamics. 
Christian Schubert (Humboldt University Berlin)