Speaker
Angelo Raffaele Fazio
(UNAL)
Description
We propose a pure four-dimensional formulation (FDF) of the d-dimensional regularization of
one-loop scattering amplitudes. In our formulation particles propagating inside the loop are rep-
resented by massive internal states regulating the divergences. The latter obey Feynman rules
containing multiplicative selection rules which automatically account for the effects of the extra-
dimensional regulating terms of the amplitude. The equivalence between the FDF and the Four
Dimensional Helicity scheme is discussed. We present explicit representations of the polarization
and helicity states of the four-dimensional particles propagating in the loop. They allow for a
complete, four-dimensional, unitarity-based construction of d-dimensional amplitudes. Generalized
unitarity within the FDF does not require any higher-dimensional extension of the Clifford and the
spinor algebra. Finally we show how the FDF allows for the recursive construction of d-dimensional
one-loop integrands, generalizing the four-dimensional open-loop approach.
Primary author
Angelo Raffaele Fazio
(UNAL)
