Feynman diagrams with the effective action

TL;DR

This paper derives Feynman rules for perturbative calculations of Green's functions in quantum many-body theories with non-quadratic actions, broadening the applicability of Feynman diagram techniques.

Contribution

It provides a systematic derivation of Feynman rules applicable to non-quadratic actions in quantum many-body theory, extending traditional methods.

Findings

Derived Feynman rules for non-quadratic actions

Applicable to a wide range of quantum many-body problems

Discussed specific applications of the rules

Abstract

A derivation is given of the Feynman rules to be used in the perturbative computation of the Green's functions of a generic quantum many-body theory when the action which is being perturbed is not necessarily quadratic. Some applications are discussed.