A nonideal Bose gas at high temperatures

Thermodynamic Green's functions are used to examine the properties of a Bose gas whose particles repel one another, not necessarily weakly, for finite temperatures T > T₀, in which T₀ is the phase-transition point and T/n^2/3 1. The excitation spectrum is deduced, together with the temperature dependence of the renormalized chemical potential and mass of the excitations.