Least-Order Torsion-Gravity for Dirac Fields, and their Non-Linearity   terms
  We will consider the most general least-order torsional completion of gravity with electrodynamics for the Dirac matter fields, and we study the effects that the torsion-spin coupling will have in inducing self-interactions among the fermion fields themselves; we will see that such self-interactions of fermions have effects analogous to those of the field-quantization prescription, and we will study the way in which they can give rise to matter distributions that are localized in a compact region and stable under the influence of perturbations. 
Luca Fabbri
gr-qc