On the spectrum of AdS3 x S3 x T4 strings with Ramond-Ramond flux

TL;DR

This paper investigates the spectrum of perturbative closed strings on AdS3 x S3 x T4 with Ramond-Ramond flux, using integrable methods to derive the S matrix, Bethe equations, and spin chain models, revealing a match with supergravity spectra.

Contribution

It introduces a detailed integrable framework for the string spectrum on AdS3 x S3 x T4 with RR flux, including the derivation of dressing factors and the construction of the associated spin chain.

Findings

Derived the massless and mixed-mass dressing factors of the worldsheet S matrix.

Constructed the integrable spin chain reproducing the weak coupling spectrum.

Matched the degeneracy of vacua with supergravity predictions.

Abstract

We analyze the spectrum of perturbative closed strings on AdS3 x S3 x T4 with Ramond-Ramond flux using integrable methods. By solving the crossing equations we determine the massless and mixed-mass dressing factors of the worldsheet S matrix and derive the Bethe equations. Using these, we construct the underlying integrable spin chain and show that it reproduces the reducible spin chain conjectured at weak coupling in arXiv:1211.1952. We find that the string-theory massless modes are described by gapless excitations of the spin chain. The resulting degeneracy of vacua matches precisely the protected supergravity spectrum found by de Boer.