The zero-temperature dispersion curve in liquid He4 is calculated assuming anomalous dispersion, ω(k)=c k(1+γ2k2), in zeroth order and including three-phonon interactions within the continuum model. It is shown that the damped-phonon mode changes to a collective-type excitation at higher momenta. Estimates of γ at saturated vapor pressure and 10 atm are obtained from experimental data on the onset of the long-lived excitation in liquid He4.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics