Spin-density and Vorticity Contribution to the Cosmological Background
  Relativistic non-Abelian spinning fluids can be formulated in group theory language, where the corresponding Mathisson-Papapetrou equation for spinning fluids can be obtained in terms of a specific de Sitter group contraction. This framework is very suitable for studying the effects of a spinning fluid of matter with vorticity and a spin density in a cosmological background. 
Dario Capasso
hep-th gr-qc