Semiclassical strings and AdS/CFT

Abstract

We discuss AdS/CFT duality in the sector of ``semiclassical'' string states with large quantum numbers. We review the coherent-state effective action approach, in which similar 2d sigma model actions appear from the AdS_5 x S^5 string action and from the integrable spin chain Hamiltonian representing the N=4 super Yang-Mills dilatation operator. We consider mostly the leading-order terms in the energies/anomalous dimensions which match but comment also on higher-order corrections.

34 pages. Contribution to Proceedings of Cargese Summer School, June 7-19, 2004, extended version of hep-th/0407218