title: Two types of quasiparticles excited in a Bose gas.
abstract: We present a novel approach for investigating the superfluid liquid 4He based on the proper use of the nonideal Bose gas model for dilute hard spheres. The results show that the presence of a macroscopic number of condensate atoms leads to the existence of a nonphysical branch, corresponding to density excitations, in addition to the continuous branch of the phonon-maxon-roton excitation spectrum.
authors.affiliation: Scientific Center of Applied Research, JINR, Dubna 141980, Russia.
authors.forename: V N
authors.initials: VN
authors.lastname: Minasyan
authors.forename: K J
authors.initials: KJ
authors.lastname: Touryan