Classical and quantum double copy of back-reaction

Abstract

We consider radiation emitted by colour-charged and massive particles crossing strong plane wave backgrounds in gauge theory and gravity. These backgrounds are treated exactly and non-perturbatively throughout. We compute the back-reaction on these fields from the radiation emitted by the probe particles: classically through background-coupled worldline theories, and at tree-level in the quantum theory through three-point amplitudes. Consistency of these two methods is established explicitly. We show that the gauge theory and gravity amplitudes are related by the double copy for amplitudes on plane wave backgrounds. Finally, we demonstrate that in four-dimensions these calculations can be carried out with a background-dressed version of the massive spinor-helicity formalism.

One-loop multicollinear limits from 2-point amplitudes on self-dual backgrounds

“…These will be restricted in momentum/helicity configuration by the support of the initial background configuration but, notably, may be of arbitrarily high multiplicity in external particle number. Exploring this expansion can provide insight into differences and similarities between amplitudes in vacuum and in backgrounds, as well as useful theoretical 'data'; examples include extracting data for the gauge theory side of an explicit double copy to gravity beyond flat backgrounds (e.g., [22][23][24][25][26][27][28]), or for alternative bases of external states (e.g., [29][30][31]).…”

Gauge × gauge = gravity on homogeneous spaces using tensor convolutions

“…One could consider a flat gluon background on a curved spacetime, a curved gluon background on flat spacetime or both non-trivial gluon and spacetime backgrounds. For example, CK duality and the double-copy in a curved 'sandwich' planewave gluon background was considered in [74,75]. The Kerr-Schild version of the double copy also admits a formulation on curved backgrounds [76,77].…”

Scattering amplitudes and the double copy in topologically massive theories

“…Along the way we will motivate the idea that topologically massive gauge and gravity theories are related via the double copy, a correspondence between gauge and gravitational theories originally formulated in the context of massless scattering amplitudes in four dimensions [23][24][25]. At this point, the double copy has been extended to include massive particles [26][27][28][29][30][31] and purely classical solutions including in three spacetime dimensions [62][63][64]. In three dimensions, however, the double copy is not so straightforward, since we almost immediately hit a road block in the sense that massless Yang-Mills theories only propagate scalar degrees of freedom and 3D general relativity propagates none, being purely topological (the Weyl tensor vanishes).…”