Prog. Theor. Phys. Vol. 61 No. 2 (1979) pp. 367-383
The Elementary Excitation Spectra of Liquid Helium II
Department of Physics, Tokyo Metropolitan University, Tokyo 158
*Department of Engineering Physics, The University of Electro-Communications, Tokyo 182
**665, Tsurumi, Tsurumi-ku, Yokohama 230
(Received October 16, 1978)
To derive, starting with the first principle, the elementary excitation spectra of the many-boson system interacting via nonsingular and net repulsive forces is the purpose of the present paper.
The effects of the Bose condensation and the pair correlation are taken into account by means of the Hugenholtz-Pines prescription and the Bogoliubov transformation respectively, and thus the quasiparticle energy and the residual interaction between them are defined. Owing to an energy gap, however, the unrenormalized quasiparticle cannot be seen as a phonon, so that the residual interaction between quasiparticles should be taken into account. To this end, the normal mode method truncated at some order is used, and we reveal the whole aspects of the excitation spectra of the boson system considered within the random phase approximation.
On the basis of the results derived, we attempt to interpret the observed excitation spectra of liquid helium II.
DOI : 10.1143/PTP.61.367
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Citing Article(s) :
Progress of Theoretical Physics Vol. 63 No. 4 (1980) pp. 1170-1180
Microscopic Derivation of the Roton-Roton Interaction