Positive helicity Einstein-Yang-Mills amplitudes from the double copy method

Josua Faller, Jan Plefka

Abstract:

All positive helicity four-point gluon-graviton amplitudes in Einstein-Yang-Mills
theory coupled to a dilaton and axion field are computed at the leading one-loop
order using colour-kinematics duality. In particular, all relevant contributions in
the gravitational and gauge coupling are established. This extends a previous
generalized unitarity based computation beyond the leading terms in the gravi-
tational coupling $\kappa$. The resulting purely rational expressions take very compact
forms. The previously seen vanishing of the single-graviton-three-gluon amplitude
at leading order in $\kappa$ is seen to be lifted at order $\kappa^3$.