Brenda Penante, Sayeh Rajabi, Grigory Sizov
Using the recent formula presented by He and Cachazo-Skinner for the link representation of tree-level N=8 supergravity amplitudes, we derived a CSW-like expansion for the Next-to-MHV 6- and 7-graviton amplitudes by using the global residue theorem; a technique introduced originally for Yang-Mills amplitudes. We analytically checked the equivalence of one of the CSW terms and its corresponding Risager diagram. For the remaining 6-graviton and all 7-graviton terms, we numerically checked the agreement with the Risager's expansion. We showed that the conditions for the absence of contributions at infinity of the global residue theorem are satisfied for any number of particles. This means that this technique and Risager should disagree starting at twelve particles where Risager is known to fail.
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http://arxiv.org/abs/1212.6257
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