A class of colliding waves in metric-affine gravity, nonmetricity and   torsion shock waves
  By using our recent generalization of the colliding waves concept to metric-affine gravity theories, and also our generalization of the advanced and retarded time coordinate representation in terms of Jacobi functions, we find a general class of colliding wave solutions with fourth degree polynomials in metric-affine gravity. We show that our general approach contains the standard second degree polynomials colliding wave solutions as a particular case. 
Alfredo Macias, Claus Laemmerzahl, and Alberto Garcia