Iordanskiiʹs force for superfluid vortices revisited: a critical analysis

Iordanskiiʹs force for quantised superfluid vortices was originally derived for a rotating weakly interacting Bose gas. Various attempts were made to obtain that force from the two-fluid model for He II. A closer examination shows, however, that these efforts were not successful. We therefore propose an alternative derivation of Iordanskiiʹs force. The analysis is made for quantised vortices with either a singular or a hollow core. It turns out that the physical origin of Iordanskiiʹs force resides in the fact that the elementary excitations participate in the circulating motion of the superfluid around the vortex core. Although Iordanskiiʹs original analysis is, apparently, in conformity with this observation, that property of a quantised superfluid vortex underlying Iordanskiiʹs force does not seem to have been well recognised by subsequent authors.