验证2 PI再确认：Bloch-Nordsieck示例

Resummations in the Bloch-Nordsieck model

We studied different levels of resummations of the exactly solvable Bloch-Nordsieck model in order to be able to compare the approximations with an exact result. We studied one-loop perturbation theory, 2PI resummation and Schwinger-Dyson equations truncated in a way to maintain Ward-identities. At all levels we carefully performed renormalization. We found that although the 2PI resummation does not exhibit infrared sensitivity at the mass shell (the one-loop perturbation theory does), but it is still far from the exact solution. The method of truncated Schwinger-Dyson equations, however, is e…

量子电动力学中的红外多光子重传

Infrared multiphoton resummation in quantum electrodynamics

自从量子场论建立以来，人们就知道无质量规范理论中的红外奇异性。这个问题的根源可以追溯到这些长程相互作用理论（如QED）的定义。可以证明，奇点是由无质量的自由度（即量子电动力学中的光子）引起的。在Bloch-Nordsieck模型中，红外灾变的不存在可以通过辐射修正的完全求和来精确地证明。在本文中，我们将给出的想法推导的布洛赫Nordsieck传播，描述了红外结构的电子传播，在零温度和有限的温度。最后，对可能的应用提出了一些设想。