Classical instanton and wormhole solutions of Type IIB string theory
  We study $p=-1$ D-brane in type IIB superstring theory. In addition to RR instanton, we obtain the RR charged wormhole solution in the Einstein frame. This corresponds to the ten-dimensional singular wormhole solution with infinite euclidean action. 
Jin Young Kim (Dongseo University), H.W. Lee and Y.S. Myung (Inje   University)