Construction of theory of a binary mixture of nonideal bose gases (or liquids) by the method of collective variables. III. Perturbation theory

For a binary mixture of nonideal Bose gases (or liquids) the method of collective variables [1] is used to construct a perturbation theory, and the corrections of lowest order to the wave function and energy of the ground state are found. For the model of a “hard-sphere pseudopotential” (and the use of the zeroth approximation [1]) the results of computer experiments are given. It has been established numerically that for any density and concentration of the admixture (second component) and arbitrary (but allowed by the theory of [1]) scattering lengths a binary Bose mixture does not separate. The application of the theory to $\mathrm {He}^4$ and $\mathrm D_2$ or $\mathrm {He}^4$ and $\mathrm {HT}$.