On the effect of repulsive pair interactions on Bose–Einstein condensation in the Luttinger–Sy model

In this paper we investigate the effect of repulsive pair interactions on Bose-Einstein condensation in a well-established random one-dimensional system known as the Luttinger-Sy model at positive temperature. We study separately hard core interactions as well as a class of more general repulsive interactions, also allowing for a scaling of certain interaction parameters in the thermodynamic limit. As a main result, we prove in both cases that for sufficiently strong interactions all eigenstates of the non-interacting one-particle Luttinger-Sy Hamiltonian as well as any sufficiently localized one-particle state are almost surely not macroscopically occupied.