The Yang-Lee edge singularity is a non-unitary CFT found by tuning the magnetic field in the Ising model to a critical imaginary value.

It has Ginzburg-Landau description as a scalar field with interaction $i g \phi^3$, and so is weakly coupled in $d=6-\epsilon$  [[https://arxiv.org/abs/2505.06369 | 1]]. 


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

  * [[https://en.wikipedia.org/wiki/Lee%E2%80%93Yang_theory|Wikipedia]]