Properties of multi-particle Green's and vertex functions within Keldysh formalism
Properties of multi-particle Green's and vertex functions within Keldysh formalism
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凯尔迪什形式主义中多粒子格林函数和顶点函数的性质
DOI：
10.1088/1751-8113/43/10/103001
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
H. Schoeller
中科院分区：
文献类型：
--
作者：
S. G. Jakobs;M. Pletyukhov;H. Schoeller
对凝聚态理论中非平衡效应的兴趣日益增加，促使各种平衡技术适应Keldysh形式主义。对于基于多粒子格林函数或顶点函数的方法，这涉及到对这些函数的实时属性的详细了解。在这篇综述中，我们得到了用Keldysh形式描述的费米子和玻色子多粒子格林函数和定态顶点函数的一般性质。特别强调了与因果关系有关的解析性质，并详细讨论了表征热平衡的Kubo-Martin-Schwinger条件。最后，我们描述了图解逼近和泛函重整化群方法中的逼近如何尊重这些性质。
The increasing interest in nonequilibrium effects in condensed matter theory motivates the adaption of diverse equilibrium techniques to Keldysh formalism. For methods based on multi-particle Green's or vertex functions, this involves a detailed knowledge of the real-time properties of those functions. In this review, we derive general properties of fermionic and bosonic multi-particle Green's and vertex functions for a stationary state described within Keldysh formalism. Special emphasis is put on the analytic properties associated with causality and on a detailed discussion of the Kubo–Martin–Schwinger conditions which characterize thermal equilibrium. Finally we describe how diagrammatic approximations and approximations within the functional renormalization group approach respect these properties.