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Two-particle renormalizations in many-fermion perturbation theory: Importance of the Ward identity

V. Janis
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Abstract

We analyze two-particle renormalizations within many-fermion perturbation expansion. We show that present diagrammatic theories suffer from lack of a direct diagrammatic control over the physical two-particle functions. To rectify this we introduce and prove a Ward identity enabling an explicit construction of the self-energy from a given two-particle irreducible vertex. Approximations constructed in this way are causal, obey conservation laws and offer an explicit diagrammatic control of singularities in dynamical two-particle functions.

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V. Janis. 2002-11-05. Two-particle renormalizations in many-fermion perturbation theory: Importance of the Ward identity. https://doi.org/10.1088/0953-8984%2F15%2F21%2F102

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