Hydrodynamics of 2-group global symmetries

by Dr Napat Poovuttikul (University of Iceland)

Monday 27 Jan 2020, 13:15 → 14:15 Europe/Stockholm

132:028 (Nordita East)

What is the global symmetry of a matter coupled dynamical electromagnetic field when the system itself contained a gauged mixed anomaly? And what is its appropriate IR description at finite temperature and dynamical magnetic field?
For certain anomalies, the answer for the first question is a structure called 2-group global symmetry. This is a certain combination of symmetries of point-like operators and ('t Hooft)line-operators, characterised by an integer. I will explain what a 2-group is in the language of the Green-Schwarz mechanism for the background fields and show how to consistently build a "hydrodynamic" description from this symmetry data. Purely from macroscopic considerations, I will explain why the resulting EFT cannot be a patched up 'Navier-Stokes' and Maxwell equation but must contains an additional zero mode. The latter is the manifestation of the fermion zero modes in the anomalous theory before gauging. Their current correlators in the IR, fixed by global symmetry, and some observable effects will also be discussed.