New Representations of the Perturbative S Matrix

Christian Baadsgaard, N. E.J. Bjerrum-Bohr, Jacob L. Bourjaily, Simon Caron-Huot, Poul H. Damgaard, Bo Feng

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59 Scopus citations


We propose a new framework to represent the perturbative S matrix which is well defined for all quantum field theories of massless particles, constructed from tree-level amplitudes and integrable term by term. This representation is derived from the Feynman expansion through a series of partial fraction identities, discarding terms that vanish upon integration. Loop integrands are expressed in terms of "Q-cuts" that involve both off-shell and on-shell loop momenta, defined with a precise contour prescription that can be evaluated by ordinary methods. This framework implies recent results found in the scattering equation formalism at one loop, and it has a natural extension to all orders - even nonplanar theories without well-defined forward limits or good ultraviolet behavior.

Original languageEnglish (US)
Article number061601
JournalPhysical review letters
Issue number6
StatePublished - Feb 10 2016

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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