A dense Bose fluid at zero temperature: condensation and clusters in liquid 4He
Physics Department, The University of
Received in final form: 4 December 2013
Published online: 24 July 2014
We present a full set of wave equations describing a dense Bose fluid, applicable both to non-ideal gases and to liquid 4He. The phonon spectrum in liquid 4He is found and the fraction of condensed particles is calculated at zero temperature for a wide range of densities. The theory also yields the ground-state energy for the quantum liquid 4He in agreement to high accuracy with Monte Carlo simulations and experimental data at low pressure. A new and essential point is the the introduction of a momentum space cutoff at the speed of the second sound. We also present the derivation of a generalized Hartree-Fock equation describing roton clusters in low temperature liquid 4He, allowing us to confirm that, at low enough temperatures and for a wide range of pressures, the stable clusters consist of 13 bound atoms.
Key words: Cold Matter and Quantum Gas
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2014