Effective field theory for fluids: Hall viscosity from a Wess-Zumino-Witten term

We propose an effective action that describes a relativistic fluid with Hall viscosity. The construction involves a Wess-Zumino-Witten term that exists only in (2+1) spacetime dimensions. We note that this formalism can accommodate only a Hall viscosity which is a homogeneous function of the entropy and particle number densities of degree one.