Chiral fermions and torsion in the early Universe

TL;DR

This paper explores how torsion from fermionic matter in Einstein-Cartan gravity affects early Universe cosmology, highlighting ambiguities in modeling chiral fermions and their impact on the Friedmann equation.

Contribution

It identifies and discusses ambiguities in implementing torsion from chiral fermions in early Universe models within Einstein-Cartan theory.

Findings

Torsion can contribute negatively to the energy density in chiral models.

Chemical potentials may influence the Friedmann equation through torsion effects.

Ambiguities in modeling torsion from hot fermionic matter are significant in early Universe cosmology.

Abstract

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.