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- Title
Phonon and Optical-roton Branches of Excitations of the Bose System.
- Authors
Poluektov, Yu. M.; Soroka, A. A.
- Abstract
For a system of a large number of Bose particles, a chain of coupled equations for the averages of field operators is obtained. In the approximation where only the averages of one field operator and the averages of products of two operators at zero temperature are taken into account, there is derived a closed system of dynamic equations. Taking into account the finite range of the interaction potential between particles, the spectrum of elementary excitations of a many-particle Bose system is calculated, and it is shown that it has two branches: a sound branch and an optical branch with an energy gap at zero momentum. At high density, both branches are nonmonotonic and have the roton-like minima. The dispersion of the phonon part of the spectrum is considered. The performed calculations and analysis of experiments on neutron scattering allow to make a statement about the complex structure of the Landau dispersion curve in the superfluid 4 He.
- Subjects
PHONONS; QUASIPARTICLES; BAND gaps; NEUTRON scattering; NUMBER systems; BOSE-Einstein condensation; SPIN excitations
- Publication
Journal of Low Temperature Physics, 2023, Vol 210, Issue 1/2, p68
- ISSN
0022-2291
- Publication type
Article
- DOI
10.1007/s10909-022-02885-8