Poles at infinity in on-shell diagrams

Abstract

In this paper we study on-shell diagrams in 𝒩 < 4 supersymmetric Yang-Mills (SYM) theory. These are on-shell gauge invariant objects which appear as cuts of loop integrands in the context of generalized unitarity and serve as building blocks for amplitudes in recursion relations. In the dual formulation, they are associated with cells of the positive Grassmannian G+(k, n) and the on-shell functions can be reproduced as canonical differential forms. While for the case of the 𝒩 = 4 maximally supersymmetric Yang-Mills theory all poles in on-shell diagrams correspond to IR poles when the momentum flows in edges are zero, for 𝒩 < 4 SYM theories there are new UV poles when the loop momenta go to infinity. These poles originate from the prefactor of the canonical dlog form and do not correspond to erasing edges in on-shell diagrams. We show that they can be interpreted as a diagrammatic operation which involves pinching a loop and performing a “non-planar twist” on external legs, which gives rise to a non-planar on-shell diagram. Our result provides an important clue on the role of poles at infinite momenta in on-shell scattering amplitudes, and the relation to non-planar on-shell functions.

Higher-loop integrated negative geometries in ABJM

“…2 A Thermodynamic Bethe Ansatz approach for the computation of Γcusp was recently studied for the ABJM theory in [40]. 3 For the negative geometries in the N = 4 sYM theory the first "loops of loops" diagram shows up at L = 3 [19,50]. The canonical forms of all one-cycle geometries are given in [50].…”

“…3 For the negative geometries in the N = 4 sYM theory the first "loops of loops" diagram shows up at L = 3 [19,50]. The canonical forms of all one-cycle geometries are given in [50].…”

On-shell functions on the Coulomb branch of $$\mathcal{N}$$ = 4 SYM

“…Singularities of on-shell functions for theories without maximal supersymmetry has been studied recently in[50].…”