AI 中文总结
本综述探究双副本思想在非平直时空的适用性，阐述弯曲空间中边界关联函数等的构造及多种双副本映射，指出平直空间结构的保留与曲率带来的阻碍。
AI 中文摘要
双副本将引力数据与规范理论数据关联，最显著的是通过平直空间散射振幅的色运动学对偶实现。本综述探究该思想在渐近平直背景之外的可适用性：先回顾用于对比的平直空间要素，再描述AdS、dS及其他非平凡背景下边界关联函数与散射观测量的弯曲空间构造；随后综述克尔-席尔德、外尔、科顿、扭量及卷积双副本等经典与场层级映射，还单独讨论自对偶部分，全程强调平直空间中保留的共同结构及曲率引入的阻碍。
英文摘要
The double copy relates gravitational data to gauge-theory data, most sharply through color-kinematics duality for flat-space scattering amplitudes. This review surveys the extent to which this idea can be formulated beyond asymptotically flat backgrounds. After recalling the flat-space ingredients needed for comparison, we describe curved-space constructions for boundary correlators and scattering observables in AdS, dS, and other non-trivial backgrounds. We then review classical and field-level maps, including Kerr--Schild, Weyl, Cotton, twistor, and convolutional double copies. A separate part is devoted to self-dual sectors. Throughout, we emphasize both the common structures that survive from flat space and the obstructions introduced by curvature.
Comments191 pages plus appendices and references, invited review article for Physics Reports
