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arXiv 1705.04539hep-thhep-ph
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坐标空间振幅的路径描述

Path description of coordinate-space amplitudes

Ozan Erdoğan, George Sterman

摘要:

我们开发了一个坐标版本的光锥有序微扰理论,一般的时间顺序产品的领域,进行积分超过一个光锥坐标的每个相互作用的顶点。得到的表达式取决于路径的长度,在相同的光锥坐标测量。每一条路径都有一个分母,等于“光锥亏损”,类似于动量时空或光锥有序微扰理论中的“能量亏损”。实际上,动量空间中的中间态所扮演的角色是由坐标空间中外部场之间的路径所扮演的。我们推导出一类坐标图所满足的恒等式,并由此导出它们的虚部。以标量QED为例,我们展示了如何程函近似自然出现时,在一个格林函数的外部点接近光锥,我们给威尔逊线的产品的应用。虽然我们的大部分讨论是针对在四维无质量的领域,我们扩展的形式主义,有质量的领域和维正则化。

英文摘要:

We develop a coordinate version of light-cone-ordered perturbation theory, for general time-ordered products of fields, by carrying out integrals over one light-cone coordinate for each interaction vertex. The resulting expressions depend on the lengths of paths, measured in the same light-cone coordinate. Each path is associated with a denominator equal to a "light-cone deficit", analogous to the "energy deficits" of momentum-space time- or light-cone-ordered perturbation theory. In effect, the role played by intermediate states in momentum space is played by paths between external fields in coordinate space. We derive a class of identities satisfied by coordinate diagrams, from which their imaginary parts can be derived. Using scalar QED as an example, we show how the eikonal approximation arises naturally when the external points in a Green function approach the light cone, and we give applications to products of Wilson lines. Although much of our discussion is directed at massless fields in four dimensions, we extend the formalism to massive fields and dimensional regularization.

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