Notes on D-instanton correction to AdS5×S5 geometry

We show that the D-instanton in the AdS5×S5 background is a wormhole connecting the background AdS5×S5 to the flat space R10located at the position of the D-instanton. By a SL(2,R) rotation of type IIB theory, we can make the global geometry flat in string frame. We also find that, due to the tight relation between the dilaton and the axion, there is no SL(2,R) element that takes strong string coupling to weak one without making the axion ill defined. We also discuss the D-instanton gases. A subtlety on the D-instanton at the boundary or at the horizon is discussed.