Generation of heterotic string theory solutions from the stationary Einstein–Maxwell fields

A new formalism for construction of the stationary solutions is developed for the four-dimensional gravity coupled to the dilaton, Kalb–Ramond and two Maxwell fields in a low-energy heterotic string theory form. The result of generation is automatically invariant in respect to subgroup of the stationary charging symmetry transformations; the generation can be started from the stationary Einstein–Maxwell fields. The formalism is given both in real and new compact complex form, the result of maximal symmetry extension of the stationary Einstein–Maxwell theory to discussing string gravity model is explicitly written down.