Instantons in the non-linear sigma model

TL;DR

This paper reviews the classification of finite energy solutions, called instantons, in the two-dimensional non-linear sigma model, which are crucial for understanding its vacuum structure.

Contribution

It provides a comprehensive classification of all finite energy instanton solutions in the 2D non-linear sigma model.

Findings

Classified all finite energy solutions.

Highlighted importance for vacuum structure.

Reviewed mathematical properties of instantons.

Abstract

This is a review to classify all finite energy solutios of the two dimensional non-linear sigma model. These solutions could be important in understanding the vacuum structure of the non-linear sigma model.