Superstrings on NS5 backgrounds, deformed AdS3 and holography

TL;DR

This paper explores a solvable string theory model on NS5 backgrounds that interpolates between different geometries, providing insights into holographic dualities and RG flows between Little String Theory and six-dimensional super Yang--Mills instantons.

Contribution

It constructs an exactly solvable worldsheet conformal field theory describing superstrings on a deformed NS5 background, enabling detailed analysis of deformations and holographic RG flows.

Findings

Full partition function for superstrings on SL(2,R) x SU(2) x K3

Explicit computation of current-current deformation partition functions

Identification of a holographic RG flow between Little String Theory and 6D super Yang--Mills

Abstract

We study a non-standard decoupling limit of the D1/D5-brane system, which interpolates between the near-horizon geometry of the D1/D5 background and the near-horizon limit of the pure D5-brane geometry. The S-dual description of this background is actually an exactly solvable two-dimensional (worldsheet) conformal field theory: {null-deformed SL(2,R)} x SU(2) x T^4 or K3. This model is free of strong-coupling singularities. By a careful treatment of the SL(2,R), based on the better-understood SL(2,R) / U(1) coset, we obtain the full partition function for superstrings on SL(2,R) x SU(2) x K3. This allows us to compute the partition functions for the J^3 and J^2 current-current deformations, as well as the full line of supersymmetric null deformations, which links the SL(2,R) conformal field theory with linear dilaton theory. The holographic interpretation of this setup is a renormalization-group flow between the decoupled NS5-brane world-volume theory in the ultraviolet (Little String Theory), and the low-energy dynamics of super Yang--Mills string-like instantons in six dimensions.