Color-kinematics duality, double copy and the unitarity method for higher-derivative QCD and quadratic gravity

Abstract

Here we discuss color-kinematics duality for higher-derivative QCD amplitudes. We explicitly show that the duality still holds in this case and it can be instrumental in constructing the associated quadratic-gravity amplitudes by using the double-copy prescription. This allows one to drastically simplify calculations. We also evaluate some tree-level Compton scattering amplitudes in higherderivative QCD and quadratic gravity. Furthermore, we illustrate the application of generalized unitarity method for both cases by studying a specific one-loop amplitude.

On Quadratic Gravity

“…Alternately, one can perhaps employ unitarity to reproduce the full amplitudes, as in modern unitarity based techniques. One of us (GM) has been exploring this promising pathway [42,43] Anselmi has been exploring the Feynman rules for a similar class of theories, and has introduced prescriptions which seem to work [7]. There is in principle a difference between Anselmi's program and what we have been describing.…”