Summary: | We uncover 2-group symmetries in 6d superconformal field theories. These
symmetries arise when the discrete 1-form symmetry and continuous flavor
symmetry group of a theory mix with each other. We classify all 6d
superconformal field theories with such 2-group symmetries. The approach taken
in 6d is applicable more generally, with minor modifications to include
dimension specific operators (such as instantons in 5d and monopoles in 3d),
and we provide a discussion of the dimension-independent aspects of the
analysis. We include an ancillary mathematica code for computing 2-group
symmetries, once the dimension specific input is provided. We also discuss a
mixed 't Hooft anomaly between discrete 0-form and 1-form symmetries in 6d.
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