On spherically symmetric string solutions in four dimensions

We reconsider here the problem of finding the general 4D spherically symmetric, asymptotically flat and time-independent solutions to the lowest-order string equations in the α′ expansion. Our construction includes earlier work, but differs from it in three ways: (1) We work with general background metric, dilaton, axion, and U(1) gauge fields. (2) Much of the original solutions were required to be nonsingular at the apparent horizon, motivated …