"A Deformed Model for the Unstable Phonon Spectrum in <math>4He</math>

Physics NotePublished

"A Deformed Model for the Unstable Phonon Spectrum in $<math>^4He</math>$

Marco Aurélio do Rego Monteiro; Lígia Maria Coelho de Souza Rodrigues; Stenio Wulck

1996

Authors: Marco Aurélio do Rego Monteiro; Lígia Maria Coelho de Souza Rodrigues; Stenio Wulck
Type: Physics Note
Status: Published
Publication date: 1996
Description: The theoretical derivation of the phonon anomalous dispersion relation, \linebreak <math>w^{ph} = c_0 p (1-\gamma p^2)\,\!</math>, predicts that <math>\gamma\,\!</math> is positive and therefore that the four-phonon process is the dominant scattering, thus contradicting experimental results of phonon lifetime in neutron scattering and of specific heat measurements. We show that this discrepancy between theory and experiment concerning the stability of phonon spectrum is overcome when we treat the gas of phonon excitations in <math>^4He\,\!</math> as an ideal deformed bosonic gas. When this model is compared with data from <math>^4He\,\!</math> specific heat measurements for <math>T<1\ K\,\!</math>, it reproduces within <math>5%\,\!</math> of accuracy the curves resulting from least-squares fits of those data.
Year: 1996
Number: CBPF-NF-025/96
Linked to a thesis: No
Linked to a grant: No