We continue our study of string theory in a background that interpolates between $AdS_3$ in the infrared and a linear dilaton spacetime $R^{1,1}times R_phi$ in the UV. This background corresponds via holography to a $CFT_2$ deformed by an operator of
dimension $(2,2)$. We discuss the structure of spatial entanglement in this model, and compare it to the closely related $Tbar T$ deformed $CFT_2$.
Recently we proposed a universal solvable irrelevant deformation of $AdS_3/CFT_2$ duality, which leads in the ultraviolet to a theory with a Hagedorn entropy [1]. In this note we provide a worldsheet description of this theory as a coset CFT, and com
pare its spectrum to the field theory predictions of [2,3].
It was recently shown that the theory obtained by deforming a general two dimensional conformal theory by the irrelevant operator $Tbar T$ is solvable. In the context of holography, a large class of such theories can be obtained by studying string th
eory on $AdS_3$. We show that a certain $Tbar T$ deformation of the boundary $CFT_2$ gives rise in the bulk to string theory in a background that interpolates between $AdS_3$ in the IR and a linear dilaton spacetime in the UV, i.e. to a two dimensional vacuum of Little String Theory. This construction provides holographic duals for a large class of vacua of string theory in asymptotically linear dilaton spacetimes, and sheds light on the UV behavior of $Tbar T$ deformed $CFT_2$. It may provide a step towards holography in flat spacetime.
We argue that classical $(alpha)$ effects qualitatively modify the structure of Euclidean black hole horizons in string theory. While low energy modes experience the geometry familiar from general relativity, high energy ones see a rather different g
eometry, in which the Euclidean horizon can be penetrated by an amount that grows with the radial momentum of the probe. We discuss this in the exactly solvable SL(2,R)/U(1) black hole, where it is a manifestation of the black hole/Sine-Liouville duality.
