Ruth Britto, Edoardo Mirabella
Unitarity cuts diverge in the channel of a single massive external fermion.
We propose an off-shell continuation of the momentum that allows a finite
evaluation of the unitarity cuts. If the cut is taken with complete amplitudes
on each side, our continuation and expansion around the on-shell configuration
produces the finite contribution to the bubble coefficient. Finite parts in the
expansion of the external leg counterterms must be included explicitly as well.
View original:
http://arxiv.org/abs/1109.5106
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