Six-point next-to-maximally helicity-violating amplitude in maximally supersymmetric Yang-Mills theory

We present an integral representation for the parity-even part of the two-loop six-point planar next-to-maximally helicity-violating amplitude in terms of Feynman integrals which have simple transformation properties under the dual conformal symmetry. We probe the dual conformal properties of the amplitude numerically, subtracting the known infrared divergences. We find that the subtracted amplitude is invariant under dual conformal transformations, confirming existing conjectures through two-loop order. We also discuss the all-loop structure of the six-point next-to-maximally helicity-violating amplitude and give a parametrization whose dual conformal invariant building blocks have a simple physical interpretation.