The 1/N expansion method in quantum field theory

TL;DR

This paper explains the 1/N expansion method in quantum field theory, illustrating its application with scalar and fermion models, and providing a brief overview of its relevance to QCD.

Contribution

It introduces and elucidates the 1/N expansion technique through specific models, highlighting its significance in quantum field theory analysis.

Findings

Demonstrated the 1/N expansion with the O(N) scalar model

Applied the method to the Gross-Neveu fermion model

Briefly discussed implications for QCD

Abstract

The motivations of the 1/N expansion method in quantum field theory are explained. The method is first illustrated with the O(N) model of scalar fields. A second example is considered with the two-dimensional Gross-Neveu model of fermion fields with global U(N) and discrete chiral symmetries. The case of QCD is briefly sketched.