Schwinger_parametrization
Schwinger parametrization
Loop integral parametrization
Schwinger parametrization is a technique for evaluating loop integrals which arise from Feynman diagrams with one or more loops.
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Using the well-known observation that
Julian Schwinger noticed that one may simplify the integral:
for Re(n)>0.
Another version of Schwinger parametrization is:
which is convergent as long as and .[1] It is easy to generalize this identity to n denominators.