Anomalous Magnetohydrodynamics
  Anomalous symmetries induce currents which can be parallel rather than
orthogonal to the hypermagnetic field. Building on the analogy with charged
liquids at high magnetic Reynolds numbers, the persistence of anomalous
currents is scrutinized for parametrically large conductivities when the plasma
approximation is accurate. Different examples in globally neutral systems
suggest that the magnetic configurations minimizing the energy density with the
constraint that the helicity be conserved coincide, in the perfectly conducting
limit, with the ones obtainable in ideal magnetohydrodynamics where the
anomalous currents are neglected. It is argued that this is the rationale for
the ability of extending to anomalous magnetohydrodynamics the hydromagnetic
solutions characterized by finite gyrotropy. The generally covariant aspects of
the problem are addressed with particular attention to conformally flat
geometries which are potentially relevant for the description of the
electroweak plasma prior to the phase transition.
