d-dimensional unitarity cut method

We develop a unitarity method to compute one-loop amplitudes with massless propagators in d=4−2ϵ dimensions. We compute double cuts of the loop amplitudes via a decomposition into a four-dimensional and a −2ϵ-dimensional integration. The four-dimensional integration is performed using spinor integration or other efficient techniques. The remaining integral in −2ϵ dimensions is cast in terms of bubble, triangle, box, and pentagon master integrals using dimensional shift identities. The method yields results valid for arbitrary values of ϵ.