A bstract At high energy densities, fivebranes are populated by a Hagedorn phase of so-
called little strings, whose statistical mechanics underlies black fivebrane thermodynamics …

A bstract Recently an exact worldsheet description of strings propagating in certain black
hole microstate geometries was constructed in terms of null-gauged WZW models. In this …

Motivated by a desire to find a useful 2d Lorentz-invariant reformulation of the AdS5× S5
superstring world-sheet theory in terms of physical degrees of freedom we construct the …

We consider conformal defects joining two conformal field theories along a line. We define
two new quantities associated to such defects in terms of expectation values of the stress …

A bstract String theory on AdS 3 backgrounds arises as an IR limit of Little String Theory on
NS5-branes. A wide variety of holographic RG flows from the fivebrane theory in the UV to …

Moduli spaces of conformal field theories corresponding to current-current deformations are
discussed. For WZW models, CFT and sigma model considerations are compared. It is …

A systematic group theoretical formulation of the Pohlmeyer reduction is presented. It
provides a map between the equations of motion of sigma models with target-space a …

These lectures provide an introduction to the microscopic description of branes in curved
backgrounds. After a brief reminder of the flat space theory, the basic principles and …

We review the Pohlmeyer reduction of the superstring sigma model on AdSn× Sn leading to
a gauged WZW model with an integrable potential. In particular, we consider the case of GS …

A bstract We construct a two-parameter four-dimensional non-BPS NS-NS smooth
microstate solution that asymptotes to flat spacetime with a linear dilaton in type II …