A new sound mode in liquid Helium 4?
arXiv:cond-mat/9507037 · doi:10.1016/0375-9601(94)90870-2
Abstract
This letter is based on the hypothesis of a small entropy content of the superfluid fraction of liquid helium. We show that such a superfluid entropy gives rise to a new sound mode in a ring-shaped superleak. This mode is named sixth sound. We propose an experiment by which its sound velocity and thereby the superfluid entropy can be measured. A negative experiment would yield a new upper limit for the superfluid entropy.
9 pages, latex, published in Phys. Lett. A 187 (1994) 88