DYNAMICS OF A SUPERFLUID VORTEX AND THE MAGNUS FORCE

We study the dynamics of a vortex in superfluid He4. This is carried o ut by deriving the effective Lagrangian for the center of the vortex b y starting with the time-dependent Ginzburg-Landau formalism. From the resultant equation of motion for a vortex, rye arrive at a novel aspe ct for the Magnus force which has long been known in fluid dynamics. T his force has a geometric origin and is expected to occur in other for m Of condensates such as vortex excitations for quantum Hall fluids or ferromagnets, We also consider the force of non geometric origin, the pinning force coming from the impurity.