New Non-Supersymmetric Tachyon-Free Strings

TL;DR

This paper constructs new non-supersymmetric tachyon-free string theories in various dimensions using asymmetric orbifolds, expanding the known landscape of stable string models with minimal scalar content.

Contribution

It introduces novel non-supersymmetric tachyon-free string constructions in 4d, 6d, and 8d via asymmetric orbifolds, including a quasicrystalline orbifold in 4d.

Findings

New 4d, 6d, and 8d tachyon-free string models

Models feature only one neutral scalar at tree level

Models exhibit chiral matter and positive cosmological constant

Abstract

In four decades of string theory research, only a handful of non-supersymmetric tachyon-free strings with only one neutral scalar at tree level were found. We construct new such non-supersymmetric tachyon-free string theories using asymmetric orbifolds that serve as the lower-dimensional counterparts to the $O(16) \times O(16)$ string in 4d, 6d, and 8d, each featuring only one neutral scalar at tree level, chiral matter and positive leading order cosmological constant. The 4d construction uses a quasicrystalline orbifold.