Structure of a Vortex in SuperfluidH4e

We have carried out variational calculations of the properties of a quantum vortex line in three dimensional ${}^4$He using a shadow wave function, which generates a distributed vorticity. We have calculated the radial dependence of the density, velocity field, and excitation energy and found that the latter hardly changes as the density is increased from equilibrium to near freezing. This result appears to provide an explanation of why the classical core parameter, obtained from fitting experimental data for the energy and velocity of large vortex rings, expands as the density increases.