TsT, black holes, and $T\bar T + J\bar T + T\bar J$

TL;DR

This paper constructs new string backgrounds via TsT transformations of the NS1-NS5 system, proposing a holographic dual to a specific deformed CFT, and analyzes black hole solutions, spectra, thermodynamics, and geometric properties.

Contribution

It introduces a class of string backgrounds dual to $Tar T + Jar T + Tar J$-deformed CFTs, including black holes and ground states, with detailed spectral and thermodynamic analysis.

Findings

Derived the long string spectrum and its relation to the dual field theory.

Reproduced black hole thermodynamics from the deformed CFTs.

Matched the ground state energy with the vacuum energy in the dual theory.

Abstract

We generate a class of string backgrounds by a sequence of TsT transformations of the NS1-NS5 system that we argue are holographically dual to states in a single-trace $T\bar T + J\bar T + T\bar J$-deformed CFT$_2$. The new string backgrounds include general rotating black hole solutions with two $U(1)$ charges as well as a smooth solution without a horizon that is interpreted as the ground state. As evidence for the correspondence we (i) derive the long string spectrum and relate it to the spectrum of the dual field theory; (ii) show that the black hole thermodynamics can be reproduced from single-trace $T\bar T + J\bar T + T\bar J$-deformed CFTs; and (iii) show that the energy of the ground state matches the energy of the vacuum in the dual theory. We also study geometric properties of these new spacetimes and find that for some choices of the parameters the three-dimensional Ricci scalar in the Einstein frame can become positive in a region outside the horizon before reaching closed timelike curves and singularities.