Unitarity cuts and reduction to master integrals in d dimensions for one-loop amplitudes

Charalampos Anastasiou, Ruth Britto, Bo Feng, Zoltan Kunszt, Pierpaolo Mastrolia

Published 2006-12-21, updated 2007-02-14Version 2

We present an alternative reduction to master integrals for one-loop amplitudes using a unitarity cut method in arbitrary dimensions. We carry out the reduction in two steps. The first step is a pure four-dimensional cut-integration of tree amplitudes with a mass parameter, and the second step is applying dimensional shift identities to master integrals. This reduction is performed at the integrand level, so that coefficients can be read out algebraically.