D3-brane-D-instanton configuration and N=4 super YM theory in constant self-dual background

We consider SO(4) x SO(6) invariant type IIB string solution describing D3- branes superposed with D-instantons homogeneously distributed over D3-brane world-volume. In the near D3-brane horizon limit this background interpola tes between AdS(5) x S-5 space in UV and flat space (with non-constant dila ton and RR scalar) in IR. Generalizing the AdS/CFT conjecture we suggest th at type IIB string in this geometry is dual to N = 4 SYM theory in a state with a constant self-dual gauge field background. The semiclassical string representation for the Wilson factor implies confinement with effective str ing tension depending on constant D-instanton density parameter. This provi des a simple example of type IIB string - gauge theory duality with clear D -brane and gauge theory interpretation. (C) 1999 Elsevier Science B.V. All rights reserved.