Week 06.12.2009 – 12.12.2009

After an overview of some of the achievements of the AdS/CFT correspondence when applied to realistic field theories, I will describe recent progress in the area.

The Romans mass is a discrete parameter in type IIA string theory. It is perhaps the most mysterious piece of the theory: for example, its non-perturbative, M-theoretic interpretation is still not known. In this talk, we will review recent efforts to understand it through another non-perturbative tool: holography. We will see how this parameter modifies the recent holographic interpretation of certain string vacua via Chern-Simons theories. This leads to certain field theory results that, in turn, help find new families of supersymmetric vacua of string theory with negative cosmological constant.

I will review the construction of BPS and non-BPS multicenter black hole solutions, and describe a class of smooth solutions that have the same charges and asymptotics as black holes, but do not have a horizon. I will then discuss some of the properties of these solutions and argue that they should correspond to typical microstates of extremal black holes. If so, string theory would imply that a classical extremal black hole solution is a thermodynamic approximation of an ensemble of horizonless configurations, and that this solution stops giving a valid description of the physics at the scale of the horizon. I will finish by discussing the extension of this to non-extremal black holes and its implications for the information paradox.