Molecular hydrodynamics of a weakly nonideal nondegenerate Bose gas. I. Green's functions of transverse components of particle flux density

Green's functions are obtained for the fluctuations in the densities of conserved quantities (particle number, flux, and energy); the static susceptibilities and transport coefficients are also obtained. In the case of a weakly nonideal gas of Bose particles at temperature $T$ above the critical temperature ($T>T_c$), the relations obtained are used to construct the correlation functions of the transverse components of the particle flux density; the corresponding expressions are valid in a wide range of frequencies and wave vectors.