Comments on the NSVZ $\beta$ Functions in Two-dimensional $\mathcal N=(0,2)$ Supersymmetric Models

The NSVZ $\beta$ functions in two-dimensional $\mathcal N=(0,2)$ supersymmetric models are revisited. We construct and discuss a broad class of such models using the gauge formulation. All of them represent direct analogs of four-dimensional ${\mathcal N} =1$ Yang-Mills theories and are free of anomalies. Following the same line of reasoning as in four dimensions we distinguish between the holomorphic and canonical coupling constants. This allows us to derive the exact two-dimensional $\beta$ functions in all models from the above class. We then compare our results with a few examples which have been studied previously.