Nonrotating cosmic strings interacting with gravitational waves in Einstein-Maxwell-dilaton gravity

We present methods for the construction of exact diagonal cylindrically symmetric solutions in a four dimensional low energy limit of string theory, the Einstein-Maxwell-dilaton gravity. The methods allow us to generate exact string backgrounds from known solutions to the equations of Einstein or Einstein gravity coupled to a massless scalar field. We also give and analyze explicit examples of such solutions. It is shown that they are free of curvature singularities,(quasi)regular on the axis of symmetry, asymptotically flat and describe nonrotating cosmic strings interacting with gravitational, dilaton and electromagnetic waves.