On the Momentum Distribution and Condensate Fraction in the Bose Liquid

The model recently proposed in Ref.1 is used to derive linear integro– differential equations whose solutions provide reasonable estimates for the momentum distribution and condensate fraction in interacting many–boson system at zero temperature. An advantage of these equations is that they can be employed in the weak coupling regime and beyond. As an example, analytical treatment of the weak coupling case is given. PACS: 05.30.Jp, 67.90.+z A new way of investigating spatial particle correlations has recently been proposed for the many–boson system in the ground state [1]. It results in integro–differential equations for the pair distribution function. They accurately take into account the short–range boson correlations and, in the weak coupling regime, yield thermodynamics which reasonably agrees ∗Permanent address: Obninsk Institute of Nuclear Power Engineering, Studgorodok, Obninsk, 249020, Russia