High-gradient operators in perturbed Wess–Zumino–Witten field theories in two dimensions Original Research Article

Many classes of non-linear sigma models (NLσMs) are known to contain composite operators with an arbitrary number 2s of derivatives (“high-gradient operators”) which appear to become strongly relevant within renormalization group (RG) calculations at one (or fixed higher) loop order, when the number 2s of derivatives becomes lar