Topology change and heterotic flux vacua

TL;DR

This paper explores the relationship between topology and Narain T-duality in heterotic flux vacua, revealing dual descriptions involving K3 surfaces and analyzing implications for supersymmetry and gauge groups.

Contribution

It provides evidence that heterotic flux backgrounds with 8 supercharges have T-dual descriptions involving K3 surfaces, and examines properties of flux vacua with minimal supersymmetry.

Findings

All 5 and 4D heterotic flux vacua with 8 supercharges have T-dual descriptions involving K3 surfaces.

Properties of flux vacua include roles of flat gerbes and rational worldsheet CFTs.

Dualities relate flux vacua to M-theory/heterotic duality.

Abstract

We investigate the interrelation between topology and Narain T-duality of heterotic flux vacua. We present evidence that all 5 and 4-dimensional Minkowski space heterotic flux backgrounds with 8 supercharges have a locus in the moduli space with a T-dual description in terms of a compactification on the product of a K3 surface with a circle or a torus. A test of this equivalence is provided by calculating the new supersymmetric index on both sides of the duality. We examine the implications of these dualities for CHL-like orbifolds that reduce the rank of the gauge group, as well as those that lead to minimal supersymmetry in 4 dimensions. We also discuss properties of flux vacua that preserve minimal supersymmetry in 4 dimensions that cannot be related to conventional compactifications by Narain T-duality. Along the way we point out a number of properties of these vacua, including the role played by non-trivial flat gerbes, the appearance of rational worldsheet CFTs in decompactification limits, and the role of attractive K3 surfaces in backgrounds with minimal supersymmetry. Finally, we discuss the dual pairs from the perspective of M-theory/heterotic duality.