Abstract
A solvable current-current deformation of the worldsheet theory of strings on AdS3 has been recently conjectured to be dual to an irrelevant deformation of the spacetime orbifold CFT, commonly referred to as single-trace Toverline{T} . These deformations give rise to a family of bulk geometries which realize a non-trivial flow towards the UV. For a particular sign of this deformation, the corresponding three-dimensional geometry approaches AdS3 in the interior, but has a curvature singularity at finite radius, beyond which there are closed timelike curves. It has been suggested that this singularity is due to the presence of “negative branes,” which are exotic objects that generically change the metric signature. We propose an alternative UV-completion for geometries displaying a similar singular behavior by cutting and gluing to a regular background which approaches a linear dilaton vacuum in the UV. In the S-dual picture, a singularity resolution mechanism known as the enhançon induces this transition by the formation of a shell of D5-branes at a fixed radial position near the singularity. The solutions involving negative branes gain a new interpretation in this context.
Highlights
Note that · μ denotes the expectation value computed in the theory at each point along the flow
We propose an alternative UV-completion for geometries displaying a similar singular behavior by cutting and gluing to a regular background which approaches a linear dilaton vacuum in the UV
The flow towards negative couplings may lead to severe violations of causality in the target spacetime, manifest in curvature and dilaton singularities, usually accompanied by the development of closed timelike curves (CTCs)
Summary
We begin by briefly reviewing the single-trace T Tdeformation developed in [31]. The model starts from studying string theory with AdS3 backgrounds supported by NS fluxes, which are determined by two integer charges Q1 and Q5. The ultraviolet LST vacuum corresponds to the holographic dual of a given non-local, nongravitational theory (associated to the worldvolume of N S5-branes) which is known to present Hagedorn growth at high energies [28, 30]. Where MT Tdenotes the deformation by the irrelevant double-trace T Tacting on a single factor of the symmetric product Backgrounds of this sort can be obtained from compactification of type IIB string theory vacua of the form AdS3 × N , with N some compact CFT whose central charge is determined by criticality. The effective theory associated to a single string corresponds to a single factor in (2.6) and, for states within the aforementioned perturbative regime, each factor is effectively decoupled from the rest. Seeking such an embedding will be the goal of the rest of this paper
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