Non-minimal Einstein-Yang-Mills-dilaton theory
  We establish a new non-minimal Einstein-Yang-Mills-dilaton model, for which the Lagrangian is linear in the curvature and contains eight arbitrary functions of the scalar (dilaton) field. The self-consistent system of equations for the non-minimally coupled gauge, scalar and gravitational fields is derived. As an example of an application we discuss the model with pp-wave symmetry. Two exact explicit regular solutions of the whole system of master equations, belonging to the class of pp-wave solutions, are presented. 
A.B. Balakin and H. Dehnen