New Formulas for Amplitudes from Higher-Dimensional Operators

Abstract

In this paper we study tree-level amplitudes from higher-dimensional operators, including $F^3$ operator of gauge theory, and $R^2$, $R^3$ operators of gravity, in the Cachazo-He-Yuan formulation. As a generalization of the reduced Pfaffian in Yang-Mills theory, we find a new, gauge-invariant object that leads to gluon amplitudes with a single insertion of $F^3$, and gravity amplitudes by Kawai-Lewellen-Tye relations. When reduced to four dimensions for given helicities, the new object vanishes for any solution of scattering equations on which the reduced Pfaffian is non-vanishing. This intriguing behavior in four dimensions explains the vanishing of graviton helicity amplitudes produced by the Gauss-Bonnet $R^2$ term, and provides a scattering-equation origin of the decomposition into self-dual and anti-self-dual parts for $F^3$ and $R^3$ amplitudes.

21 pages; v3: published version; a mistake in sec. 4.1 corrected

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Cited by in corpus (5)

• Combinatorics and Topology of Kawai-Lewellen-Tye Relations
• Ambitwistor formulations of $R^2$ gravity and $(DF{)}^2$ gauge theories
• Labelled tree graphs, Feynman diagrams and disk integrals
• Curvature-Squared Multiplets, Evanescent Effects and the U(1) Anomaly in N = 4 Supergravity
• A String Deformation of the Parke-Taylor Factor