Anomalies of non-Abelian finite groups via cobordism

Understand

We use cobordism theory to analyse anomalies of finite non-abelian symmetries in 4 spacetime dimensions.

• By applying the method of `anomaly interplay', which uses functoriality of cobordism and naturality of the $\eta$-invariant to relate anomalies in a group of interest to anomalies in other (finite or compact Lie) groups, we derive the anomaly for every representation in many examples motivated by flavour physics, including $S_3$, $A_4$, $Q_8$, and $\mathrm{SL}(2,\mathbb{F}_3)$.
• In the case of finite abelian groups, it is well known that anomalies can be `truncated' in a way that has no effect on low-energy physics, by means of a group extension.
• We extend this idea to non-abelian symmetries.