Orientifold and F-theory Duals of CHL Strings

TL;DR

This paper explores dual descriptions of CHL string compactifications using orientifold and F-theory frameworks, revealing how non-trivial monodromies lead to non-simply laced gauge groups and analyzing N=2 vacua in six dimensions.

Contribution

It provides explicit dual models for CHL strings in 8 and 6 dimensions, demonstrating the role of monodromy in gauge group structure within F-theory.

Findings

Non-trivial monodromy induces non-simply laced gauge groups.

Type IIA orientifold on Möbius band as dual in 8D.

Examples of N=2 F-theory vacua in 6D.

Abstract

We present orientifold and F-theory duals of the heterotic string compactification constructed by Chaudhuri, Hockney and Lykken (CHL) which has the maximal supersymmetry but gauge group of reduced rank. The 8-dimensional dual is given by the Type IIA orientifold on the M\"{o}bius band. We show the non-trivial monodromy on the base induces non-simply laced gauge groups on the F-theory orbifolds dual to the CHL strings. The F-theory models dual to the CHL strings in six dimensions are examples of N=2 F-theory vacua. We discuss the other N=2 F-theory vacua in six dimensions.