Towards the Gravituhedron: new expressions for NMHV gravity amplitudes

• Main Author: Jaroslav Trnka
• Format: Article
• Language: English
• Published: SpringerOpen 2021-04-01
• Series: Journal of High Energy Physics
• Subjects: Scattering Amplitudes; Supersymmetric Gauge Theory
• Online Access: https://doi.org/10.1007/JHEP04(2021)253

Abstract In this paper, we present new expressions for n-point NMHV tree-level gravity amplitudes. We introduce a method of factorization diagrams which is a simple graphical representation of R-invariants in Yang-Mills theory. We define the gravity analogues which we call G $$ \mathcal{G} $$ -invariants, and expand the NMHV gravity amplitudes in terms of these objects. We provide explicit formulas of NMHV gravity amplitudes up to eight points in terms of G $$ \mathcal{G} $$ -invariants, and give the general definition for any number of points. We discuss the connection to BCFW representation, special behavior under large momentum shift, the role of momentum twistors and the intricate web of spurious poles cancelation. Because of the close connection between R-invariants and the (tree-level) Amplituhedron for Yang-Mills amplitudes, we speculate that the new expansion for gravity amplitudes should correspond to the triangulation of the putative Gravituhedron geometry.