Generating Solutions via Sigma-Models

We review recent development of solution-generating techniques forfour and five-dimensional Einstein equations coupled to vector and scalar fields. This includes D = 4 Einstein-Maxwell-dilaton-axion theory with multiple vector fields, D = 5 Einstein-Maxwell gravity with the Chern-Simons term (minimal five-dimensional supergravity), and some other models which attracted attention in connection with black rings. The method is based on reduction to three-dimensional gravity coupled sigma-models with symmetric target space. Our recent results open a way to construct the general charged black rings in five-dimensional supergravity possibly coupled to vector multiplets.