Schwinger parametrization
Schwinger parametrization is a technique for evaluating loop integrals which arise from Feynman diagrams with one or more loops. It is named after Julian Schwinger, who introduced the method in 1951 for quantum electrodynamics.
Description
Using the observation thatone may simplify the integral:
for.
Alternative parametrization
Another version of Schwinger parametrization is:which is convergent as long as and. It is easy to generalize this identity to n denominators.