Gravitational wave double copy of radiation from gluon shockwave collisions

Abstract

In a recent paper, we showed that the gravitational wave spectrum from trans-Planckian shockwave scattering in Einstein gravity is determined by the gravitational Lipatov vertex expressed as the bilinear double copy $Γ^{μν} = \frac12 C^μC^ν- \frac12 N^μN^ν$ where $C^μ$ is the QCD Lipatov vertex and $N^μ$ is the QED soft photon factor. We show here that this result can be directly obtained by careful application of the classical color-kinematic duality to the spectrum obtained in gluon shockwave collisions.