Four-fermion interaction from torsion as dark energy

TL;DR

This paper explores how torsion-induced four-fermion interactions, possibly originating from early Universe quark condensates, could explain the small positive cosmological constant, considering modifications to the Dirac Lagrangian.

Contribution

It investigates the effects of additional parity-violating and nonminimal coupling terms on torsion-induced four-fermion interactions in cosmology.

Findings

Torsion-induced four-fermion interactions can contribute to dark energy.

Adding nonminimal coupling terms modifies the interaction dynamics.

The model suggests a possible origin for the cosmological constant from fermion condensates.

Abstract

The observed small, positive cosmological constant may originate from a four-fermion interaction generated by the spin-torsion coupling in the Einstein-Cartan-Sciama-Kibble gravity if the fermions are condensing. In particular, such a condensation occurs for quark fields during the quark-gluon/hadron phase transition in the early Universe. We study how the torsion-induced four-fermion interaction is affected by adding two terms to the Dirac Lagrangian density: the parity-violating pseudoscalar density dual to the curvature tensor and a spinor-bilinear scalar density which measures the nonminimal coupling of fermions to torsion.