 One-loop beta function of a supersymmetric gauge theory

With the index convention $I(\mathbf{N})=1$ for an $SU(N)$ fundamental, an N=1 supersymmetric gauge theory has $b_0=\frac{3}{2}I(\mathrm{adj})-\frac{1}{2}{\sum }_{i}I(R_i)$. Positive $b_0$ gives asymptotic freedom, while negative $b_0$ makes the gauge interaction infrared free near the Gaussian fixed point.