Anomaly Matching in 6d $\mathcal{N}=(2,0)$ SCFTs from M5 Cobordism

Abstract: We investigate the anomalies of 6d $\mathcal{N} = (2, 0)$ superconformal field theories for any ADE gauge group using the modern characterization of anomalies by cobordism. We propose that, in order to account for all features of the anomaly, a bordism theory with exotic tangential structure is needed. We then attempt to match the anomaly in the IR effective theory on the tensor branch with a suitable WZW term. Once again, we show that the exotic bordism structure is necessary to achieve this. Our results suggest a natural explanation for the origin of the Hopf-Wess-Zumino term.