The complex-mass scheme for perturbative calculations with unstable particles

Perturbative calculations with unstable particles require the inclusion of their finite decay widths. A convenient, universal scheme for this purpose is the complex-mass scheme. It fully respects gauge-invariance, is straightforward to apply, and has been successfully used for the calculation of various tree-level processes and of the electroweak radiative corrections to e(+)e(-) -> 4f and H -> 4f.