SOME INSTANTON SOLUTIONS IN STRING THEORY

In recent work Rey presented an exterior instanton solution for the massless fields in the low-energy limit of heterotic string theory to lowest order in alpha'. We extend this solution to O(alpha') in bosonic string theory and present several related solutions. For the spherically symmetric solution, the corresponding Weyl invariant sigma model is the product of a Wess-Zumino-Witten model and a one-dimensional conformal field theory. An exact solution is then obtained by fixing the metric and antisymmetric tensor field in their lowest order form and rescaling the dilation order by order in alpha'.