2-group global symmetries, hydrodynamics and holography

Understand

2-group global symmetries are a particular example of how higher-form and conventional global symmetries can fuse together into a larger structure.

• We construct a theory of hydrodynamics describing the finite-temperature realization of a 2-group global symmetry composed out of $U(1)$ zero-form and $U(1)$ one-form symmetries.
• We study aspects of the thermodynamics from a Euclidean partition function and derive constitutive relations for ideal hydrodynamics from various points of view.
• Novel features of the resulting theory include an analogue of the chiral magnetic effect and a chiral sound mode propagating along magnetic field lines.