Ordinary Matter in Nonlinear Affine Gauge Theories of Gravitation
  We present a general framework to include ordinary fermionic matter in the metric--affine gauge theories of gravity. It is based on a nonlinear gauge realization of the affine group, with the Lorentz group as the classification subgroup of the matter and gravitational fields. 
A.L\'opez--Pinto, A.Tiemblo and R.Tresguerres