Bose condensation into a state with finite momentum

The occurrence in a strongly nonideal Bose system of a Bose condensate each of whose particles has a finite modulus and arbitrary direction of the momentum is considered. The mean momentum of the complete condensate is zero. Such condensation in the case of an isotropic and homogeneous system is possible when the lowest singleparticle state with zero energy corresponds to nonzero modulus of the momentum.