Flat deformations of type IIB S-folds

TL;DR

This paper characterizes flat deformations of type IIB S-folds using group theory, introduces a 5D interpretation via duality twists, and constructs new stable, non-supersymmetric S-fold backgrounds with two deformation parameters.

Contribution

It provides a group-theoretical framework for flat deformations of S-folds and constructs the first known stable, non-supersymmetric type IIB backgrounds with these deformations.

Findings

Identified two flat deformations causing symmetry breaking to U(1)^2.

Established a 5D interpretation through duality twists and gaugings.

Constructed a new two-parameter family of stable, non-supersymmetric S-folds.

Abstract

Type IIB S-folds of the form $\textrm{AdS}_{4} \times \textrm{S}^1 \times \textrm{S}^5$ have been shown to contain axion-like deformations parameterising flat directions in the 4D scalar potential and corresponding to marginal deformations of the dual S-fold CFT's. In this note we present a group-theoretical characterisation of such flat deformations and provide a 5D interpretation thereof in terms of $\mathfrak{so}(6)$-valued duality twists inducing a class of Cremmer--Scherk--Schwarz flat gaugings in a reduction from 5D to 4D. In this manner we establish the existence of two flat deformations for the $\mathcal{N}=4$ and $\textrm{SO}(4)$ symmetric S-fold causing a symmetry breaking down to its $\textrm{U}(1)^2$ Cartan subgroup. The result is a new two-parameter family of non-supersymmetric S-folds which are perturbatively stable at the lower-dimensional supergravity level, thus providing the first examples of such type IIB backgrounds.