𝒩 = 4 single-minus superamplitudes and dual superconformal symmetry

A bstract We construct the 𝒩 = 4 supersymmetric completion of the recently proposed single-minus gluon amplitudes in (2 , 2) signature, which are nonvanishing for all multiplicities on a half-collinear kinematic locus. The superamplitude factorises into a permutation-invariant measure ∆ ( n −1) with uniform little-group weight that imposes the half-collinearity constraint, a piecewise constant stripped amplitude $${\widetilde{A}}_{1\dots n}$$ that is helicity blind and dual conformal invariant, and (super)momentum conservation delta functions. For n = 3, our superamplitude reduces to the known $$\overline{\text{M}\text{H}\text{V} }$$ superamplitude. We prove dual superconformal covariance of the n -point superamplitude, and further analyse the Gr( k, n ) Grassmannian integral at k = 1. Finally, we present the corresponding single-minus superamplitude in 𝒩 = 8 supergravity.