SU(6) model revisited

We discuss the vacuum structure of the SU(6) model, a chiral gauge theory, from the perspective of anomaly matching. To this end, we first identify all possible 't Hooft anomalies in the UV theory using the Stora-Zumino procedure. Subsequently, we construct an effective theory by applying the idea of the Wess-Zumino-Witten action to derive the topological terms that encode the 't Hooft anomalies. As a result, we demonstrate that a low-energy effective theory reproducing one of the anomalies, namely the mixed anomaly, is described by a Z3-valued scalar field. On the other hand, the effective theory that accounts for the discrete chiral self-anomaly is significantly more intricate, and elucidating its structure remains an ongoing challenge.