# Exponentially suppressed cosmological constant with enhanced gauge symmetry in heterotic interpolating models

## TL;DR

This paper constructs nine-dimensional heterotic string models with parameter-dependent gauge symmetry enhancement, demonstrating conditions for exponential suppression of the cosmological constant and presenting a tachyon-free, non-supersymmetric model with E_8 symmetry.

## Contribution

It introduces new interpolating heterotic string models with gauge symmetry enhancement and exponential cosmological constant suppression, including a tachyon-free non-supersymmetric example.

## Key findings

- Gauge symmetry enhancement occurs at specific radius and Wilson line conditions.
- Exponential suppression of the cosmological constant is achieved at SO(18) d7 SO(14) enhancement.
- A tachyon-free, non-supersymmetric model with E_8 gauge symmetry is constructed.

## Abstract

A few nine-dimensional interpolating models with two parameters are constructed and the massless spectra are studied by considering compactification of heterotic strings on a twisted circle with Wilson line. It is found that there are some conditions between radius R and Wilson line A under which the gauge symmetry is enhanced. In particular, when the gauge symmetry is enhanced to SO(18) \times SO(14), the cosmological constant is exponentially suppressed. We also construct a non-supersymmetric string model which is tachyon-free in all regions of moduli space and whose gauge symmetry involves E_8.