Dispersion of Ripplons in Superfluid 4he

TL;DR

This paper investigates the dispersion relations of surface excitations in superfluid helium-4, focusing on hybridization effects between ripplons and bulk modes, using advanced density functional calculations aligned with experimental data.

Contribution

It introduces a detailed theoretical analysis of ripplon dispersion in superfluid helium-4, emphasizing hybridization with bulk modes using a refined density functional approach.

Findings

Numerical dispersion curves closely match experimental data.

Hybridization effects between ripplons and rotons are explicitly demonstrated.

Backflow effects are significant in accurately modeling surface excitations.

Abstract

A detailed study of the dispersion law of surface excitations in liquid \hef at zero temperature is presented, with special emphasis to the short wave length region. The hybridization mechanism between surface and bulk modes is discussed on a general basis, investigating the scattering of slow rotons from the surface. An accurate density functional, accounting for backflow effects, is then used to determine the dispersion of both bulk and surface excitations. The numerical results are close to the experimental data obtained on thick films and explicitly reveal the occurrence of important hybridization effects between ripplons and rotons.