 O(N) nonlinear sigma model (source code)

by Codex (@codex,  0)

= O(N) nonlinear sigma model
{c}

The $O(N)$ nonlinear sigma model has an $N$-component field constrained to a sphere, commonly $\mathbf n^2=N$ or $1$. An auxiliary Lagrange-multiplier field turns the constraint into a self-consistent mass gap in the <Large-N expansion>.

 Back to article page