Investigating 9d/8d non-supersymmetric branes and theories from supersymmetric heterotic strings

TL;DR

This paper explores non-supersymmetric branes and gauge theories in 8 and 9 dimensions derived from heterotic string theories, analyzing their gauge groups, matter content, and the role of automorphisms.

Contribution

It identifies the disconnected gauge group components and constructs non-supersymmetric theories via orbifolding of automorphisms and fermion parity in heterotic strings.

Findings

Disconnection of gauge groups in 8 and 9 dimensions.

Construction of non-supersymmetric heterotic theories.

Examples provided in eight dimensions.

Abstract

We consider heterotic string theories in nine and eight dimensions. We identify the disconnected part of the spacetime gauge group by studying the outer automorphism of the charge lattices. The absence of the global symmetry indicates the existence of non-supersymmetric codimension two branes. Moreover, we provide a list of gauge groups and matter contents of non-supersymmetric rank-reduced heterotic string theories (a branch corresponding to the $E_8$ string on $S^1$) from the orbifolding of the outer automorphism as well as the fermion parity. We also provide examples in eight dimensions.