We investigate a higher-group structure of massless axion electrodynamics in (3 + 1) dimensions. By using the background gauging method, we show that the higher-form symmetries necessarily have a global semistrict 3-group (2-crossed module) structure, and exhibit’t Hooft anomalies of the 3-group. In particular, we find a cubic mixed’t Hooft anomaly between 0-form and 1-form symmetries, which is specific to the higher-group structure.
|Publication status||Published - 2020 Sep 29|
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