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arXiv · 1605.02638

Superfluid 4He dynamics beyond quasiparticle excitations

K. Beauvois·C. E. Campbell·J. Dawidowski·B. Fåk·H. Godfrin·E. Krotscheck·H. -J. Lauter·T. Lichtenegger·J. Ollivier·A. Sultan
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Abstract

The dynamics of superfluid 4He at and above the Landau quasiparticle regime is investigated by high precision inelastic neutron scattering measurements of the dynamic structure factor. A highly structured response is observed above the familiar phonon-maxon-roton spectrum, characterized by sharp thresholds for phonon-phonon, maxon-roton and roton-roton coupling processes. The experimental dynamic structure factor is compared to the calculation of the same physical quantity by a Dynamic Many-body theory including three-phonon processes self-consistently. The theory is found to provide a quantitative description of the dynamics of the correlated bosons for energies up to about three times that of the Landau quasiparticles.

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K. Beauvois, C. E. Campbell, J. Dawidowski, B. Fåk, H. Godfrin, E. Krotscheck, H. -J. Lauter, T. Lichtenegger, J. Ollivier, A. Sultan. 2016-05-09. Superfluid 4He dynamics beyond quasiparticle excitations. https://doi.org/10.1103/physrevb.94.024504

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