Progress of Theoretical Physics
Description of Mixed States Based on the Time-Dependent Hartree-Fock Theory. I: Formalism of Thermo Field Dynamics in Canonical Theory with Constraints
A. Kuriyama, João da Providência, M. Yamamura
Abstract
Formalism of thermo field dynamics in classical mechanics with constraints, which is a natural consequence of the time-dependent Hartree-Fock theory for mixed states, is reformulated under the introduction of a gauge fixing condition. With the aid of this condition, the formulation is performed in the frame of Dirac's canonical theory with constraints. Any physical quantity can be expressed in terms of constraint-independent canonical variables.