New singular and nonsingular colliding wave solutions in Einstein-Maxwell-scalar theory (Q1420835)

The authors deal with a method that adds scalar fields to any known Einstein-Maxwell equation. The physically interesting case is to find solutions without singularities. This seems to be possible when the background colliding Einstein-Maxwell metric is singularity free in the interaction region. Any solution that is already singular here comes worse with the addition of scalar fields. The \(M\)-shift techniques applies equally well to any vacuum metric.