Based on two fundamental ideas of N.N. Bogolyubov, namely the concept of quasi-means and the method of reduced description, the effect of crystal lattice on the dynamics of a superfluid is taken into account within the framework of microscopic description. The coefficient of deceleration of normal velocity is expressed in terms of the correlation function. Equations of motion are derived for densities of additive integrals of motion and superfluid momentum. The positive definiteness of entropy production is proved.
Department of Quantum Statistics and Field Theory, Faculty of Physics, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
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