====== $O(N)$ model ======

{{tag>3d holographic}}

The special cases of the [[o2_model]] and [[o3_model]] are particularly well-studied. Higher values of $N$ do come up occasionally, see for instance the [[o4_model]]. The [[Ising|Ising model]] is the case $N=1$, and the case $N=0$ is covered by  [[self_avoiding_walk|self-avoiding walks]].

This also goes by the name of the "n-vector model", or "non-linear $\sigma$ model$.

===== Large-N limit =====

[[https://arxiv.org/pdf/hep-th/0210114.pdf]]

===== External links =====

  * [[https://en.wikipedia.org/wiki/N-vector_model|Wikipedia]]