Relativistic superfluid hydrodynamics

Abstract

Relativistic Riemannian superfluid hydrodynamics used in general relativity to investigate superfluids in pulsars is extended to non-Riemannian background spacetime endowed with Cartan torsion. From the Gross-Pitaeviskii (GP) it is shown that in the weak field Cartan torsion approximation, the torsion vector is orthogonal to the superfluid plane wave velocity. Torsion vector is also shown to be aligned along the vortex direction in the superfluid. The background torsion is shown to induce rotation on the fluid as happens with the acoustic torsion in the analogue non-Riemannian non-relativistic superfluid models. The torsion part of the current would be connected to the normal part of the superfluid velocity while the Riemannian part of the velocity would be connected to the superfluid velocity itself. Magnus effect and the rotation of the superfluid are analysed. Since the Kalb-Ramond field is easily associated with torsion our method seems to be equivalent to the vortex-cosmic string relativistic superfluid method developed by Carter and Langlois to investigate rotating neutron stars.