Aspects of instanton dynamics in AdS/CFT duality

We consider aspects of instanton dynamics in the large-N limit using the Ad S/CFT duality for D0/D4 bound states. In the supergravity picture of wrappe d D0-brane world-lines on D4-branes, we find the single-instanton measure a nd discuss its dependence on compactification finite-size effects, as well as its matching to perturbative results. In the non-supersymmetric ease, th e same dynamical effects that produce the theta-angle dependence perturbati vely in 1/N, render the instantons unstable, although approximate instanton s of very small size still exist. The smeared D0/D4 black-brane supergravity solution can be interpreted as d ual to a field theory configuration of an instanton condensate in the vacuu m. In this case, we derive a holographic relation between the bare theta an gle and the topological charge density of the instanton condensate. (C) 199 9 Published by Elsevier Science B.V. All rights reserved.