30 Progress of Theoretical Physics Supplement No. 152, 2003 Loop Effects in AdS/CFT and Beyond

Double-trace operators which are relevant deformations of large N conformal field the-ories give rise to renormalization group flows that can be studied on both sides of the AdS/CFT duality. One-loop calculations in AdS can be compared successfully to results derived in field theory using the Hubbard-Stratonovich transformation. The calculations do not rely on supersymmetry, and they apply in any dimension, provided the original conformal field theory and its AdS dual are well-defined. A speculative idea is proposed for solving the cosmological constant problem based on non-gravitational strings that become light as the universe expands. This is a summary of my talk presented at the Nishinomiya-Yukawa Symposium in Nishinomiya, Japan. It is based primarily on [S. S. Gubser and I. Mitra, hep-th/0210093; S. S. Gubser and I. R. Klebanov, hep-th/0212138]. The study of renormalization group flows in AdS/CFT3)–5) is a fairly well-developed subject, reviewed partially in Refs. 6), 7). In order to put my main topic — RG flows caused by double-trace operators — in context, I will briefly re