Schwinger-Dyson type equations for some QFT models

TL;DR

This paper develops a technique based on variational equations for effective action to derive Schwinger-Dyson type equations in various quantum field theory models, extending their applicability beyond QED.

Contribution

It introduces a novel method using variational equations to derive Schwinger-Dyson equations for models like nonlinear sigma and scalar field theories.

Findings

Derived Schwinger-Dyson equations for nonlinear sigma model

Extended the approach to scalar field theory

Provided a systematic technique for various QFT models

Abstract

The Schwinger-Dyson equations connecting free and full Green functions and vertex parts widely were used in QED for finding full Green functions under different conditions. Undoubtedly, the same approach should leads to derivation of many useful information about other models of QFT. In this work we present some technique based on variational equations for effective action to derive many different Schwinger-Dyson type equations in QFT models such as nonlinear sigma model and scalar field theory.