Hydrodynamic theory of magnets with complete spontaneous symmetry breaking

A microscopic approach to the description of the dynamics of magnets with complete spontaneous symmetry breaking is proposed. The structure of the source that breaks the symmetry of the equilibrium Gibbs distribution is established, and additional thermodynamic parameters (Cartan forms) that characterize the equilibrium state are introduced. The quasiaverage representation is generalized to locally equilibrium states, and the thermodynamics of such states is constructed. The flux densities of the additive integrals of the motion are represented in terms of the local-equilibrium thermodynamic potential. An expression is found for the orthogonal rotation matrix in terms of an arbitrary statistical operator. A method of reduced description is formulated, and “hydrodynamic” equations of the considered magnets are obtained.