arXiv:0804.3170
FERMILAB-PUB-08-092-T
IFIC-08-21
IPPP-08-22
SLAC-PUB-13218
JHEP 0809 (2008) 065

by: Catani, Stefano (INFN, Florence) et al.

Abstract:
We derive a duality relation between one-loop integrals and phase-space integrals emerging from them through single cuts. The duality relation is realized by a modification of the customary +i0 prescription of the Feynman propagators. The new prescription regularizing the propagators, which we write in a Lorentz covariant form, compensates for the absence of multiple-cut contributions that appear in the Feynman Tree Theorem. The duality relation can be applied to generic one-loop quantities in any relativistic, local and unitary field theories. It is suitable for applications to the analytical calculation of one-loop scattering amplitudes, and to the numerical evaluation of cross-sections at next-to-leading order.