A nonminimally coupled, conformally extended Einstein-Maxwell theory of pp-waves

Abstract

A nonminimal coupling of Weyl curvatures to electromagnetic fields is considered in Brans-Dicke-Maxwelltheory. The gravitational field equations are formulated in a Riemannian spacetime where the spacetime torsion isconstrained to zero by the method of Lagrange multipliers in the language of exterior differential forms. The significanceand ramifications of nonminimal couplings to gravity are examined in a pp-wave spacetime.