Quantum relativistic hydrodynamics of systems with broken symmetry. I. Local-equilibrium state

The nonequilibrium statistical operator method is used to construct a two-velocity relativistic hydrodynamics of a quantum-field system with broken symmetry and complex scalar order parameter. The approach is based on model expansions of the operators (the energy-momentum tensor, the current density, etc.) used for statistical description of the system in the hydrodynamic stage. In the first part of the paper, these expansions are used to construct the statistical operator and the thermodynamics of a local-equilibrium state.