Cubic interactions in superfluid $^4$He

ORAL

Abstract

High-resolution neutron resonance spin-echo measurements of superfluid $^4$He show that the roton energy does not have the same temperature dependence as the inverse lifetime, in contrast to the Landau-Khalatnikov theory. We present a diagrammatic analysis that attributes this effect to the interaction of rotons with thermally excited phonons via both four- and three-particle processes, the latter being allowed by the broken gauge symmetry of the Bose condensate.

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Authors

  • Bjorn F{\aa}k

    • CEA, Grenoble

  • Thomas Keller

    • MPI, Stuttgart

  • Michael Zhitomirsky

    • CEA, Grenoble

  • Alexander Chernyshev

    • University of California, Irvine