Evidence for Intrinsic Angular Momentum in SuperfluidHe3-A

I show that the observed large rotation-induced mutual friction in superfluid ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ close to $T_c$ implies a reactive interaction between the normal fluid and a vortex, similar to a Magnus force. In the $A$ phase the absence of a singular vortex core enables a purely hydrodynamic description of this interaction to be given, and I argue from hydrodynamics that the experimental observations require the existence of an intrinsic angular-momentum density of order $\left(\frac{{\rho }_s\hslash }{2m}\right)\hat{1}$.