For example, beginning with a sigma model whose target space is the 2-sphere they found an exactly solvable Sine-Gordon model.

In physics, a sigma model is a physical system that is described by a Lagrangian density of the form:

A scalar field model encoding chiral symmetry and its breaking is the sigma model.

Fubini-Study metric, a metric often used with non-linear sigma models.

Asymptotically safe weak interactions based on some nonlinear sigma models.

This is also known as nonlinear sigma model.

In theoretical physics, harmonic maps are also known as sigma models.

The idea is related to a property of the bosonic string in a curve background, better known as nonlinear sigma model.

Still, nonlinear sigma models transform nonlinearly, so there are applications.

Higher genus symplectic invariants and sigma models coupled with gravity.