Gauge-Invariant Double Copies via Recursion Relations.

We prove by construction that all tree-level amplitudes in pure (super)gravity can be expressed as termwise, gauge-invariant double copies of those of pure (super-)Yang-Mills obtained via on-shell recursion. These representations are far from unique: varying the recursive scheme leads to a wide variety of distinct but equally valid representations of gravitational amplitudes, all realized as double copies.

Elliptic, Yangian-Invariant "Leading Singularity".

We derive closed formulas for the first examples of nonalgebraic, elliptic "leading singularities" in planar, maximally supersymmetric Yang-Mills theory and show that they are Yangian invariant.