A quadratic curvature Lagrangian of Paw{\l}owski and R\c{a}czka: a   finger exercise with MathTensor
  Recently Paw{\l}owski and R\c{a}czka proposed a unified model for the fundamental interactions which does not contain a physical Higgs field. The gravitational field equation of their model is rederived under heavy use of the computer algebra system Mathematica and its package MathTensor. 
Efstratios Tsantilis, Roland A. Puntigam, and Friedrich W. Hehl   (Institute for Theoretical Physics, University of Cologne,...