The Energy Momentum Tensor of Chiral Quark Models at Low Energies
  The low energy structure of the energy momentum tensor in several chiral quark models with SU(3) flavor symmetry is analyzed in the presence of external gravitational fields. To this end a derivative expansion in a curved four dimensional space time is considered. This allows us to compute the chiral coefficients $L_{11}$, $L_{12}$, and $L_{13}$, appearing when the model is coupled to gravity and related to space-time curvature properties. 
E. Megias, E. Ruiz Arriola, L.L. Salcedo