Boundary Spectra in Superspace Sigma-Models

TL;DR

This paper computes exact boundary spectra for D-instantons in supergroup sigma-models, revealing properties of the perturbation series and implications for string theory on AdS3 with RR-flux.

Contribution

It provides an explicit all-orders summation of conformal dimensions for D-instantons in PSL(2|2) sigma-models, highlighting unique properties of the perturbation series.

Findings

Exact boundary spectra for D-instantons computed

Perturbation series exhibits remarkable properties

Implications for string theory on AdS3 with RR-flux

Abstract

In this note we compute exact boundary spectra for D-instantons in sigma-models on the supergroup PSL(2|2). Our results are obtained through an explicit summation of the perturbative expansion for conformal dimensions to all orders in the curvature radius. The analysis exploits several remarkable properties of the perturbation series that arises from rescalings of the metric on PSL(2|2) relative to a fixed Wess-Zumino term. According to Berkovits, Vafa and Witten, the models are relevant in the context of string theory on AdS3 with non-vanishing RR-flux. The note concludes with a number of comments on various possible generalizations to other supergroups and higher dimensional supercoset theories.