Perturbation Theory in Supersymmetric QED: Infrared Divergences and Gauge Invariance
Abstract: I will discuss some aspects of perturbation theory in N=1 supersymmetric abelian gauge theories with massive charged matter (i.e. SUSY QED). In general gauges, infrared (IR) divergences and nonlocal behavior arise in one-particle irreducible (1PI) diagrams, associated with a term in the vector superfield propagator with a forth power of momentum in the denominator. The IR divergences are gauge-dependent and must cancel in physical quantities like the electron pole mass. This cancellation takes place in a nontrivial way, amounting to a reorganization of the perturbative series in powers of the electric charge. I will also touch on how these complications are avoided in cases where a Wilsonian effective action can be defined.
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