In this review we describe a non-trivial relationship between perturbative gauge theory and gravity scattering amplitudes. At the semi-classical or tree-level, the scattering amplitudes of gravity theories in flat space can be expressed as a sum of products of well defined pieces of gauge theory amplitudes. These relationships were first discovered by Kawai, Lewellen, and Tye in the context of string theory, but hold more generally. In particular, they hold for standard Einstein gravity. A method based on D-dimensional unitarity can then be used to systematically construct all quantum loop corrections order-by-order in perturbation theory using as input the gravity tree amplitudes expressed in terms of gauge theory ones. More generally, the unitarity method provides a means for perturbatively quantizing massless gravity theories without the usual formal apparatus associated with the quantization of constrained systems. As one application, this method was used to demonstrate that maximally supersymmetric gravity is less divergent in the ultraviolet than previously thought.

中文翻译：

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微扰量子引力及其与规范理论的关系。


在这篇综述中，我们描述了微扰规范理论和重力散射振幅之间的重要关系。在半经典或树级别，平坦空间中重力理论的散射振幅可以表示为规范理论振幅的明确定义的片段的乘积之和。这些关系首先由 Kawai、Lewellen 和 Tye 在弦理论的背景下发现，但更普遍。特别是，它们适用于标准爱因斯坦引力。然后，可以使用基于 D 维幺正性的方法，以规范理论振幅表示的重力树振幅作为输入，系统地构建微扰理论中的所有量子环校正。更一般地，幺正性方法提供了一种用于扰动量化无质量重力理论的方法，而无需与约束系统的量化相关的通常的形式装置。作为一种应用，该方法用于证明最大超对称重力在紫外线中的发散程度比以前认为的要小。