TsT, $T\bar{T}$ and black strings

TL;DR

This paper explores how TsT transformations relate to $Tar{T}$ and similar deformations in 2D CFTs, constructing black string solutions and analyzing their holographic duals, revealing bounds on deformation parameters and matching spectra and thermodynamics.

Contribution

It establishes a holographic correspondence between TsT transformations and $Tar{T}$ deformations, and constructs new black string solutions dual to deformed CFT states.

Findings

TsT transformations correspond to specific irrelevant deformations of 2D CFTs.

Constructed black string solutions dual to $Tar{T}$-deformed CFTs.

Identified an upper bound on the deformation parameter and matched thermodynamic properties.

Abstract

We study the relationship between TsT transformations, marginal deformations of string theory on AdS$_3$ backgrounds, and irrelevant deformations of 2d CFTs. We show that TsT transformations of NS-NS backgrounds correspond to instantaneous deformations of the worldsheet action by the antisymmetric product of two Noether currents, holographically mirroring the definition of the $T\bar{T}$, $J\bar{T}$, $T\bar{J}$, and $J\bar{J}$ deformations of 2d CFTs. Applying a TsT transformation to string theory on BTZ $\times S^3\times M^4$ we obtain a general class of rotating black string solutions, including the Horne-Horowitz and the Giveon-Itzhaki-Kutasov ones as special cases, which we show are holographically dual to thermal states in single-trace $T\bar{T}$-deformed CFTs. We also find a smooth solution interpolating between global AdS$_3$ in the IR and a linear dilaton background in the UV that is interpreted as the NS-NS ground state in the dual $T\bar{T}$-deformed CFT. This background suggests the existence of an upper bound on the deformation parameter above which the solution becomes complex. We find that the worldsheet spectrum, the thermodynamics of the black strings (in particular their Bekenstein-Hawking entropy), and the critical value of the deformation parameter match the corresponding quantities obtained from single-trace $T\bar{T}$ deformations.