Non-geometric Calabi-Yau Backgrounds and K3 automorphisms

TL;DR

This paper explores non-geometric string compactifications involving K3 fibrations with mirror symmetries, connecting geometric automorphisms to asymmetric Gepner models and identifying resulting Minkowski vacua with N=2 supersymmetry.

Contribution

It introduces a novel class of non-geometric Calabi-Yau backgrounds using K3 automorphisms and links them to asymmetric Gepner models, expanding the understanding of string vacua.

Findings

Identified gaugings of N=4 supergravity corresponding to these backgrounds.

Found Minkowski vacua preserving N=2 supersymmetry with the STU model.

Connected worldsheet formulations to supergravity descriptions of the vacua.

Abstract

We consider compactifications of type IIA superstring theory on mirror-folds obtained as K3 fibrations over two-tori with non-geometric monodromies involving mirror symmetries. At special points in the moduli space these are asymmetric Gepner models. The compactifications are constructed from non-geometric automorphisms that arise from the diagonal action of an automorphism of the K3 surface and of an automorphism of the mirror surface. We identify the corresponding gaugings of N=4 supergravity in four dimensions, and show that the minima of the potential describe the same four-dimensional low-energy physics as the worldsheet formulation in terms of asymmetric Gepner models. In this way, we obtain a class of Minkowski vacua of type II string theory which preserve N=2 supersymmetry. The massless sector consists of N=2 supergravity coupled to 3 vector multiplets, giving the STU model. In some cases there are additional massless hypermultiplets.