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arXiv 0810.4293hep-th
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关于路径积分公式的粒子图像中的QFT结构

On the Structure of QFT in the Particle Picture of the Path Integral Formulation

D. M. Jackson, A. Kempf, A. Morales

摘要:

在量子场论中,路径积分通常在波图像中表示,即,场演化的总和。这个路径积分很难严格定义,因为解析问题的解决可能最终需要非微扰甚至普朗克尺度物理学的知识。或者,QFT可以直接在粒子图像中公式化,即作为所有多粒子路径的总和,即,费曼图这个路径积分是定义良好的,作为一个正式的幂级数环之间的映射。这就提出了一个程序,用于确定QFT的哪些结构对于这个路径积分是可证明的,因此在本质上是组合的,以及哪些结构实际上对分析问题是敏感的。首先,我们表明,事实上,勒让德变换的连通图的总和产生的有效行动确实是组合的性质,因此是独立的分析假设。我们的证明也导致了新的方法,有效的分解成$n$ -粒子不可约(nPI)的子图的费曼图。

英文摘要:

In quantum field theory the path integral is usually formulated in the wave picture, i.e., as a sum over field evolutions. This path integral is difficult to define rigorously because of analytic problems whose resolution may ultimately require knowledge of non-perturbative or even Planck scale physics. Alternatively, QFT can be formulated directly in the particle picture, namely as a sum over all multi-particle paths, i.e., over Feynman graphs. This path integral is well-defined, as a map between rings of formal power series. This suggests a program for determining which structures of QFT are provable for this path integral and thus are combinatorial in nature, and which structures are actually sensitive to analytic issues. For a start, we show that the fact that the Legendre transform of the sum of connected graphs yields the effective action is indeed combinatorial in nature and is thus independent of analytic assumptions. Our proof also leads to new methods for the efficient decomposition of Feynman graphs into $n$-particle irreducible (nPI) subgraphs.

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