STRING-MOTIVATED MODEL

The two-dimensional model which emerges from low-energy considerations of string theory is written down. Solutions of this classical model a re noted, including some examples which have a nontrivial tachyon fiel d. One such example represents the classical back reaction of the tach yon field on the black hole for a two parameter set of tachyon potenti als. Assuming the classical black hole background in the ''Eddington-F inkelstein'' gauge, the tachyon equation is separable and the radial p art is solved by a hypergeometric function, which is in general of com plex argument. A semiclassical prescription for including the quantum effects of the tachyon field is described, and the resulting equations of motion are found. Special solutions of these equations are written down.