Chiral fermions and torsion in the early Universe
  Torsion arising from fermionic matter in the Einstein-Cartan formulation of
general relativity is considered in the context of Robertson-Walker geometries
and the early Universe. An ambiguity in the way torsion arising from hot
fermionic matter in chiral models should be implemented is highlighted and
discussed. In one interpretation, chemical potentials in chiral models can
contribute to the Friedmann equation and give a negative contribution to the
energy density.
