Semi-doubled Sigma Models for Five-branes

TL;DR

This paper introduces a semi-doubled gauged linear sigma model (GLSM) framework that captures both original and dual degrees of freedom, facilitating the study of T-duality and nongeometric backgrounds in string theory.

Contribution

The authors develop a new semi-doubled GLSM approach that simplifies deriving dual systems and models exotic nongeometric branes, extending the understanding of T-duality in string theory.

Findings

Constructed semi-doubled GLSM for H-monopoles and $5^3_2$-brane.

Derived T-dualized systems using the semi-doubled approach.

Identified emergence of nongeometric features in the $5^3_2$-brane model.

Abstract

We study two-dimensional ${\cal N}=(2,2)$ gauge theory and its dualized system in terms of complex (linear) superfields and their alternatives. Although this technique itself is not new, we can obtain a new model, the so-called "semi-doubled" GLSM. Similar to doubled sigma model, this involves both the original and dual degrees of freedom simultaneously, whilst the latter only contribute to the system via topological interactions. Applying this to the ${\cal N}=(4,4)$ GLSM for H-monopoles, i.e., smeared NS5-branes, we obtain its T-dualized systems in quite an easy way. As a bonus, we also obtain the semi-doubled GLSM for an exotic $5^3_2$-brane whose background is locally nongeometric. In the low energy limit, we construct the semi-doubled NLSM which also generates the conventional string worldsheet sigma models. In the case of the NLSM for $5^3_2$-brane, however, we find that the Dirac monopole equation does not make sense any more because the physical information is absorbed into the divergent part via the smearing procedure. This is nothing but the signal which indicates that the nongeometric feature emerges in the considering model.