Bogolyubov spectrum (1) for the “hard spherical shells” potential (solid curve) fitted as closely as possible to the experimental spectrum (dotted curve) in the region for with and ( is the mass of a helium atom).
Fourier component of the “semitransparent spheres” potential (dashed curve) and the corresponding renormalized potential (solid curve), obtained in Refs. 23–25 taking account of the momentum dependence of the polarization operator (see the relation (17)), which is negative on the mass shell (see Fig. 3).
Momentum dependence of the boson polarization operator on the “mass shell,” obtained in Ref. 23 by means of self-consistent numerical calculations with (solid curve) and (dashed curve).
Theoretical quasiparticle spectrum obtained in Refs. 23–25 by means of self-consistent calculations in the “semitransparent spheres” model (solid curve) taking account of the momentum dependence of the polarization operator with . The dots show the experimental spectrum of He II.
Theoretical quasiparticle spectrum calculated in Ref. 24 on the basis of a combined potential obtained by matching the Lennard–Jones potential with the screened coulomb potential taking account of the momentum dependences of the polarization operator and the vertex part (solid curve). The dots and asterisks show the experimental data obtained from measurements of the spectrum of He II.5,34,35
Momentum dependences of the functions (a) and (b) obtained in Refs. 23–25 by means of self-consistent numerical calculations for the “semitransparent spheres” model.
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