Regarding the relation between the photon-roton spectrum and the single-particle excitation spectrum in liquids with Bose-Einstein condensate

Abstract

An analysis of the existing theoretical ideas as to the relationship between the spectrum of collective density excitations and the spectrum of single-particle excitations in liquids with a Bose-Einstein condensate. Using available experimental results, we examine the problem of the relationship between the collective phonon-roton excitations in different liquids, and the Bose-Einstein condensate.